Mars

Energy on Mars, Part 2

Solar

In the short term, solar energy is the simplest way to obtain energy on Mars, which is why we use solar panels on rovers such as Pathfinder, Spirit and Opportunity.

An MER (Mars Exploration Rover) showing solar panels
An MER (Mars Exploration Rover) showing solar panels

Because Mars is farther from the Sun it receives less incident solar energy per square metre. It’s also smaller than Earth, with about half the radius, which means it also receives less total solar energy.

Mars has a fairly elliptical orbit, which means the distance between Mars and the Sun varies considerably, between about 207 and 249Gm (gigametres, or millions of kilometres). Therefore the intensity of solar energy reaching Mars varies as much as 20% during a Martian year. Earth’s orbit is much more circular, and we don’t see as much variation in solar intensity. The distance between Earth and the Sun varies between about 147 and 152Gm.

We can calculate a ballpark comparison between the amount of solar energy reaching Mars and Earth using average distances:

Average distance between Sun and Earth = 150Gm

Average distance between Sun and Mars = 228Gm

The intensity of solar energy decreases with the square of the distance, because it’s spread out over area. Therefore:

Solar energy at Earth: Ee = k/de2

Solar energy at Earth: Em = k/dm2

where k is some constant of proportionality.

To compare: Em/Ee = de2/dm2 = 1502/2282 = 0.43 = 43%

This calculation suggests that the amount of solar energy per square metre on Mars is only about 43% of that on Earth. In reality, there’s very little cloud cover on Mars and the atmosphere is much thinner than Earth’s, which tends to boost that figure. On the other hand, there’s also a lot of suspended dust in the Martian atmosphere, which tends to reduce it. Overall, the intensity of incident solar energy is about half Earth’s.

This lower level of solar energy on Mars is not as serious a problem as it might first seem. Solar energy is currently experiencing a revolution on Earth – the technology is rapidly advancing, and the price is also rapidly decreasing. The solar energy technology currently being developed now will be available by the time we’re sending humans to Mars. We’ll be significantly better at collecting solar energy in the time frame of human settlement of Mars.

The primary downside of solar energy on a planetary surface is that it’s intermittent (that is, unless the planet is tidally locked to a star). Solar energy can only be collected from a point on the surface of the planet when the Sun is visible from that point; in other words, during the day time. However, methods for storing solar energy are also advancing rapidly.

Strip of solar panels at the Mars One base
Strip of solar panels at the Mars One base

Wind

It’s well-known that Mars is windy. In fact, it’s this windiness that kept the Mars Exploration Rovers, Spirit and Opportunity, rolling for as long as they did, because the wind kept blowing dust off the solar panels. Hopefully the same thing will happen to solar panels at a Mars base, thereby reducing the time and energy required for maintenance.

Wind energy has also experienced a revolution on Earth in recent years, with great improvements in turbine technology and efficiency, and considerable reductions in price, to the point where wind has achieved grid parity or better in many regions. Wind is now one of the most important energy sources in north-west Europe and Scandinavia.

Even though Mars is windy, leveraging wind energy on Mars as a major power source may be difficult. This is because the air pressure is very low, less than 1% of Earth’s, which means that even if the wind is moving fast the amount of force it can generate is very small. Therefore it would not be able to force high turbine speeds or generate much electricity. Nonetheless, Mars’ low gravity could help out here, enabling construction of very tall wind turbines with long blades, which will be able to effectively harness Martian wind.

Another factor is that the air on Mars is full of very fine, suspended dust, which could get into turbine bearings and cause them to wear down. This problem is likely to be solvable with good engineering design, but that may not happen until we have a permanent human presence on Mars.

A large desert wind farm, similar to what we could build on Mars.
A large desert wind farm, similar to what we could build on Mars.

Areothermal

It has not yet been established conclusively whether or not Mars contains hyperthermal zones (“hot spots”) in the shallow crust that could be utilised for energy. On Earth we refer to this as geothermal energy, however, the word “geothermal” becomes “areothermal” on Mars because we replace the prefix “geo”, which refers to Earth, with the prefix “areo”, which refers to Mars. (Other examples: geology/areology, geography/areography, geosynchronous/areosynchronous, etc.)

On Earth, geothermal energy holds great promise as being the only form of sustainable energy considered capable of providing baseline power. Solar and wind energy are intermittent, and therefore require an energy storage solution such as rechargeable batteries. However, these are generally expensive, inefficient, and not very environmentally friendly.

A reliable source of areothermal energy on Mars will be of exceptional value, possibly superior to all other energy options currently under consideration. Areothermal energy provides a continuous abundant supply of energy, like fission, but without the risk and waste issues. It does not require storage solutions like solar or wind, does not to be launched into space like SSP (Space Solar Power), and can also be used directly for settlement heating or as a source of hot water. If it’s eventually shown that areothermal energy is only available in a few places, these places may well be settled first. Settlements close to both an areothermal energy source and significant water and/or mineral resources will be at a significant advantage.

Basic geothermal power plant
Basic geothermal power plant

One of the challenges associated with geothermal energy is efficiently distributing electricity, as geothermal power plants are often geographically distant from users, and distributing electricity through copper wires introduces losses proportional to distance (compare with traditional coal-fired power stations, which can be located close to, or in, cities). However, as with solar and wind, significant advancements have been made in recent years in geothermal technology, and it’s now possible to access geothermal energy in more places. This increases the amount of geothermal energy is available for use, while also reducing distances between sources and consumers.

The prevailing view is that Mars has cooled to the point where it’s effectively areologically inactive. However, research by the planetary engineering expert Martin Fogg (see: The Utility of Geothermal Energy on Mars, 1996) shows that regions of Mars with very low crater counts, which have been recently resurfaced by magmatism, may be indicative of regions of above-average heat flow on Mars and may therefore potentially offer sources of areothermal energy. According to his research, regions with the highest probability of offering areothermal energy are almost completely contained in one large area of Mars:

In fact they are almost exclusively located in the planet’s northwest quadrant, from longitude 220° in Elysium eastward to longitude 20° in Acidalia Plantia and north of 15°S and south of 50°N. Such is the clustering of such outcrops in adjacent geographic areas that one can surmise the existence of a distinct province of recent anomalous heat flow on Mars, including Elysium, Amazonis Planitia, Arcadia Planitia and Tharsis.

The challenge for Mars, of course, is that accessing geothermal energy requires deep drilling, a capability we will probably not have on Mars until we have permanent settlements and some sort of industrial base.

Such are the advantages of areothermal energy, if it is shown to be practical for Mars, and if this area is particularly rich in this resource, it may be settled earlier than other regions of Mars. As Fogg writes:

Some of the first permanent Martian communities could spring up around such geothermal oases. By the latter half of the next century, the spa towns of Mars might even be known for offering the best of high life on the high frontier.

Fission

It seems very likely that at least some early-stage H2M missions will make use of nuclear fission energy. Almost all Mars mission architectures specify the need for a small nuclear reactor to power the ISSP (In Situ Propellant Production) equipment in an ERV (Earth Return Vehicle) or MAV (Mars Ascent Vehicle), and to provide power and heat to the hab. Modern nuclear reactors are able to produce energy for decades without maintenance, and can provide an abundant supply of energy. Unlike solar, nuclear energy is not subject to diurnal variations and is not affected by dust or weather.

In the past, I have been very opposed to the use of nuclear energy on Mars as well as Earth. My concern was that a Chernobyl-like steam explosion combined with a planet-wide dust storm or even normal Martian winds, would distribute radioactive dust across the whole planet. As you can imagine, this would be disastrous for present and future settlements over almost the entire planet and would significantly compromise scientific studies of Mars, in particular the search for extant life, and could also seriously hamper settlement efforts. I felt that if we allowed even just one nuclear reactor on Mars, it would set a precedent that would lead to hundreds or thousands. Without sufficient qualified people or an industrial infrastructure, it would simply be a matter of time before an accident occurred. In addition, we would be creating a nuclear waste problem. Nuclear waste is hard to manage and dispose of on Earth. On Mars, waste management would be even more difficult, and we may risk ruining the Martian environment before human settlement even gets into full swing.

However, I’ve since learned that this opposition was born of ignorance, that not all nuclear energy is the same, and that appropriate use of nuclear energy is an enabling factor that makes H2M far more possible. The described problems may be characteristic of Generation I and II nuclear reactors (almost all reactors currently in use are Gen II), however, in terms of development we are now up to Generation IV, which encompasses a variety of reactor types that are considerably safer, cheaper and better.  The one particular type that I believe holds the most promise for both Earth and Mars is the LFTR (Liquid Fluoride Thorium Reactor), which is fuelled with thorium.

LFTR’s offer significant advantages over current uranium reactors:

  • Thorium is a much more common element than uranium, and is abundant on Earth, the Moon and Mars. It’s therefore cheaper.
  • LFTR’s can also be made smaller, which is useful for space applications as we want to keep the mass of hardware as low as possible.
  • LFTR’s can’t melt down. In a Gen II reactor water is used as a coolant, so if the reactor is damaged and water cannot be supplied, they can overheat catastrophically and melt down. However, if power is lost to a LFTR, the liquid fluoride salt drains away and the reaction stops.
  • Gen II uranium reactors must operate at very high pressures, up to 700 atmospheres. However, LFTR’s operate at normal pressures, so there’s no possibility of a Chernobyl-like steam explosion.
  • LFTR’s produce very little waste, because they burn almost all of their fuel. In fact, they can even use existing nuclear waste as fuel. That’s right – those pesky stockpiles of nuclear “waste” on Earth could become fuel for the next generation of nuclear reactors. Thus we have a massive, easily accessible energy source, plus the nuclear waste problem becomes solved. Obviously this feature is more important on Earth than it will be on Mars.

LFTR’s are not the only type of nuclear technology currently being developed that holds significant promise. Another is the TWR (Travelling Wave Reactor), which can be completely sealed and operate for perhaps half a century or more without maintenance. However, it seems that LFTR’s offer the most promise, especially for Mars. Both of these reactors are still in development, and not likely to be deployed on Earth for another 2 decades. However, that may well line up with our settlement plans.

Some type of small, self-contained reactors will almost certainly be used on Mars from the beginning. As to what specific reactor type this will be, that remains to be seen. But Mars has plenty of nuclear fuel, and nuclear fission technology is becoming much better.

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Mars

Energy on Mars

In order to successfully colonise Mars we’ll need access to plenty of energy. On Earth, access to abundant fossil fuels (coal, oil and natural gas) enabled the industrial revolution and continues to power human civilisation into the 21st century. Energy is necessary for heating, lighting, refrigeration, cooking and other essential basic functions of society, but perhaps most importantly it’s required by both machinery and electronics, enabling mass production, transportation, communications, computing, and all manner of automation. Modern technological society is largely dependent on machinery and electronics, and we can safely assume this will also be the case on Mars. In fact, energy requirements per person will be greater on Mars than on Earth due to the need for ECLSS (Environment Control and Life Support Systems) in habitats, pressurised vehicles and marssuits.

On Earth, the bulk of our energy comes from fossil fuels and biomass. However, as far as we know, Mars has neither of these. Mars also has no active hydrosphere, which also rules out hydroelectric, wave, tidal, and ocean thermal energy.

Here’s a breakdown of energy supply on Earth in 2010:

Oil 32.4%
Coal 27.3%
Natural gas 21.4%
Biomass 10.0%
Nuclear fission 5.7%
Hydroelectric 2.3%
Other renewables 0.9%

Thus, we’re currently obtaining over 80% of our energy from fossil fuels, but less than 1% from “Other renewables”, which includes solar, wind, wave, tidal, geothermal and ocean thermal energy sources.

On Mars, all of these are ruled out except for:

  • nuclear fission
  • solar
  • wind
  • areothermal (this is the equivalent term for “geothermal” on Mars)

Other options that are yet to be developed but may prove practical for Mars include:

  • nuclear fusion
  • space solar power

Because most energy on Earth is currently obtained from fossil fuels, most of our experience and technology related to energy production is based on harnessing these fuels. Therefore, it may at first seem like a serious challenge for settlers that Mars doesn’t provide these.

Many people say climate change is bad, but aside from all the likely death, destruction and general pandemonium, it’s also driving many positive changes on our planet. One of these, which we’re currently observing, is massive investment in new, cleaner forms of energy production.

This increase in investment and innovation is also being driven by the stark and somewhat worrying reality that fossil fuels are being consumed more rapidly than they’re being discovered or extracted, and certainly far more rapidly than they’re being made, which takes millions of years. If current demand for oil remains static, we have an estimated 120 years worth remaining on Earth. However, demand for oil is, of course, escalating exponentially as a function of both population increase and economic and technological development across the globe, and, without an effective replacement, world oil reserves could potentially be fully depleted before the end of the 21st century.

Therefore, the business case for investment in solar, wind and other renewable energy sources is solid, with about $257 billion being invested in 2011, increasing by around 20% or more per year. This is very fortunate for those of with our sights on Mars, because much of this newly developing technology can be used on the red planet.

Investment in nuclear fission has been low since the Chernobyl accident in 1986; however, there has been a renewed interest in nuclear fission lately as several environmentalists have spoken out in support of it. This may seem counter-intuitive; however, nuclear is currently viewed as less of an environmental hazard than fossil fuels, mainly because our most pressing environmental concern is currently the high concentration of atmospheric carbon dioxide caused by fossil fuel combustion. Although most environmentalists would much prefer global civilisation to be 100% powered by renewable energy sources, many experts consider it unlikely that renewables can be scaled up from their current low level quickly enough to prevent catastrophic global warming, especially considering the lack of cost-effective and environmentally-friendly energy storage solutions.

Nuclear fission is a more mature technology than most renewables, and proven as a source of cheap, abundant, continuous energy. There is still a broad public perception that nuclear fission is unreasonably dangerous, however, and that nuclear waste is also a serious environmental concern. However, several new “Generation IV” reactor designs currently in development do not have the issues that can cause Chernobyl-style disasters. One particularly promising type is the LFTR (Liquid Fluoride Thorium Reactor), which uses thorium as fuel. Thorium is much more abundant than uranium (also on the Moon and Mars), and therefore cheaper, and LFTR’s cannot melt down and can actually consume existing nuclear waste as fuel. Nonetheless, regardless of safety protocols or design, any type of fission reactor can potentially break and radioactively contaminate the environment, whether due to design or manufacturing error, operational mismanagement, natural disaster or warfare.

The most likely outcome will be that the 21st century will see massive investment in both nuclear fission as well as all major forms of renewables, and these will both gradually replace fossil fuels. If these energy sources are scaled up and deployed rapidly enough, it may even be possible that fossil fuels do not become fully depleted, at least not in the near future. The insane practice of fracking can stop, and oil can be reserved for making plastics, synthetic rubber, lubricants and other materials.

Fission may get us out of trouble in the near term, but will probably be phased out during the second half of the 21st century, as renewables such as solar, wind, wave, tidal, geothermal, ocean thermal and space solar power become increasingly advanced, widely deployed and cheap, and present a safer and cleaner option.

With regard to nuclear fusion, if developed, it’s my opinion that it will never be needed on Earth once renewable energy is abundant and cheap, which seems likely to happen sooner. However, fusion energy could prove ideal for spaceships, space stations, and lunar, asteroidal or other extraterrestrial settlements with few renewable energy options.

The current shift away from the use of fossil fuels towards nuclear fission and renewables on Earth is a boon for Mars settlers, as we can take advantage of the innovation and technological developments in this area. The development of energy production systems on Mars may even closely mirror that of Earth, with fission playing an important role in the early stages of Mars exploration and settlement, providing, as it does, an abundant supply of continuous energy, but ultimately being phased out in favour of renewable sources. As infrastructure and manufacturing capabilities are developed on Mars, including the ability to 3D print photovoltaic cells and wind turbines; as possible areothermal energy sources are discovered and exploited; and as the technology required to tap renewable energy sources and to store energy are improved and optimised for Mars, it’s reasonable to expect an eventual abandonment of nuclear fission in favour of clean, simple and safe renewables.

Architecture

Microgravity, Artificial Gravity and Blue Dragon

One of the most hotly debated topics related to sending humans to Mars is the health effects of prolonged exposure to microgravity and how these might be mitigated.

Prolonged exposure to microgravity (a.k.a. “zero gravity”) has several serious effects on the human body:

  1. Without the need to support the weight of the body, the musculoskeletal system atrophies and weakens. Bone and muscle mass tend to decrease at a significant rate. Bone mass can decrease at 1-1.5% per month.
  2. Under normal gravitational forces blood pressure is highest at the feet and legs, and lowest in the head. In microgravity, however, blood pressure is distributed evenly along the body length. The sustained, higher blood pressure in the head can affect brain function and vision.
  3. Without the need to pump blood around the body against the force of gravity, the heart does not need to work as hard and can therefore also atrophy and weaken.

The longer a person spends in microgravity the more serious these effects become, and the longer it takes to recover after they return to Earth.

H2M (Humans to Mars) and microgravity

A trip to Mars based on a long-stay, or conjunction-class, mission profile using normal chemical propulsion involves approximately a year in space – approximately 6 months outbound and about the same return. A short-stay mission requires around 20 months total in space. This is a significant amount of time to spend in a microgravity environment.

Only two people, both Russians, have spent more than one year in space: Valeri Polyakov’s 438 days in 1994-5, and Sergei Avdeyev’s 380 days in 1998-9. Therefore, we only have a small amount of data about such long-term exposure to microgravity, and much of this data is more than a decade old. Although a variety of techniques for mitigating the adverse effects of microgravity have been developed during the past decade, we have minimal data about spending a year or more in microgravity with access to these.

In addition to a year in space, the crew must also spend 1.5 years on the surface of Mars, which is also a reduced gravity environment (0.38g). Living on Mars surface will reduce the load on the body by 62% and is therefore expected to have effects proportionally similar to microgravity.

The primary concern is that the crew will return to Earth after 2.5 years in reduced gravity environments, be unable to fully recover, and have to spend the rest of their lives in wheelchairs. Apart from the fact that we wouldn’t wish this on our beloved interplanetary explorers and heroes of humanity, such an outcome would hardly add to the glory of space exploration, and may become a deterrent to future human exploration.

An almost equally important concern is that the crew will spend approximately 6 months in microgravity during the outbound trip, arrive at Mars surface, and be unable to do any useful work – thus invalidating the mission.

The problem of microgravity in an H2M mission is hardly a minor one. In conjunction with the similar concerns about health effects of radiation in interplanetary space, it’s considered by many one of the top reasons why not to send humans to Mars.

H2M and artificial gravity

Because of these concerns, some H2M mission designers include AG (Artificial Gravity) in their architecture. The simplest way that we know of to create a feeling of gravity is through the use of centrifugal force, which we can produce by spinning either part or all of the spacecraft. Unfortunately centrifugal force is not a perfect substitute for actual gravity. From DRA5:

“Adverse physiological changes due to reduced gravity may be prevented by exposure to some level of artificial gravity, but the specific level of gravity and the minimum effective duration of the exposure that is necessary to prevent deconditioning are not yet known. Although artificial gravity should reduce or eliminate the worst deconditioning effects of living in zero gravity, rotating environments frequently cause undesirable side effects, including disorientation, nausea, fatigue, and disturbances in mood and sleep patterns. If artificial gravity is to be employed, significant research must be done to determine appropriate rotation rates and durations for any artificial gravity countermeasures. The decision on whether artificial gravity must be employed to adequately support crews on their transits to and from Mars, as well as the decision on the necessary gravity level and rotation rate, has significant implications for vehicle design and operations.”

So in a sense, trading microgravity for artificial gravity is really just trading one set of health problems for another, albeit less serious. The severity of the negative effects of centrifugal force can be mitigated by increasing the radius or decreasing the rate of rotation. A spinning cylinder such as that shown in the movie Mission to Mars may seem fun, but with such a small radius these effects would be quite noticeable.

The problem is that implementing AG in an early-stage H2M mission adds considerable complexity, mass and cost, and these are exactly the kind of things we want to minimise as much as possible. It’s a classic trade-off, and hence the debate. The question is whether AG will produce a better result than a regimen of PT (Physical Training), food and drugs.

AG in Mars Direct

In Mars Direct:

“Artificial gravity is provided to the crew on the way out to Mars by tethering off the burnt out Ares upper stage and spinning up at 1 rpm.”

A spacehab connected to a counterweight by a tether, spinning around a common centre of gravity to create AG.
A spacehab connected to a counterweight by a tether, spinning to create AG.

In this way a comparatively large radius of rotation of about 340m can be created, which would seem to address the side-effects of centrifugal force. However, consider what this idea means for the architecture:

  • The hab is designed for a gravity environment: AG in space and Mars-g on Mars. That means it will have a floor, ceiling and walls, with cupboards, screens, controls, etc. mainly on the walls. The result is a less compact and heavier spacecraft (or one with fewer fixtures/features).
  • Although designed for a gravity environment, after launch the hab will be in microgravity until the AG is set up. In addition, if the AG system fails and the tether must be dropped for any reason, the hab should continue to Mars in a microgravity mode, despite not being designed for that.
  • There is a risk the counterweight could crash into the hab, and it may not be possible to prevent this even by dropping the tether.
  • The mass of the cable must also be launched (more mass, more fuel, more cost).
  • Communications with Earth are more difficult with a spinning spacecraft, as it’s more difficult to keep antennas pointed in the right direction without sacrificing signal strength. Communications with Mars are already up to one million times more difficult than with the Moon, since Mars is up to 1000 times as far away (signal strength decreases with the square of the distance).
  • With a spinning spacecraft it’s more difficult for navigation sensors to track the position of Earth, the Moon and stars.
  • Collecting solar energy with solar panels is more difficult and possibly less efficient, as they should ideally be always directly facing the Sun.
  • The hab and the counterweight both require an RCS (Reaction Control System), which must work in tandem in order to produce a stable spin around a common centre of gravity, or for any course manoeuvres.
  • Additional fuel is required for RCS on both the hab and the upper stage.
  • Additional fuel is required to send not just the hab, but also the upper stage, on TMI (Trans Mars Injection).
  • Course corrections and other manoeuvres are more difficult, as both the spacecraft and counterweight must be pushed in the same direction at the same time, without overstressing and breaking the tether, or causing it to stretch and rebound, or causing it to become slack. Plus, the dynamics of the spinning masses must also be accounted for.
  • As the assembly approaches Mars it must be spun down and the tether dropped before aerocapture. However, this will leave the spacecraft on a trajectory that is difficult to predict in advance with precision, making it more difficult to calculate the required burn to place the spacecraft on an aerocapture trajectory. It may have to be re-calculated in real time, which is risky. Yet for aerocapture to work, the hab must hit the atmosphere at exactly the right angle and altitude. EDL (Entry, Descent and Landing) is already a very technically challenging and dangerous process, especially in a hab – this additional factor makes it even more dangerous.
  • Once the assembly must be spun down, the interior of the hab will return to a weightless environment, despite not being designed for that.
  • If the tether breaks for some reason (e.g. micrometeoroid) the hab and counterweight will fly off in different directions. The hab must carry additional fuel to make a course correction if this happens. In addition, the ground crew must be prepared to track and communicate with the spacecraft (which may be on an unknown trajectory) and assist with on-the-fly calculations to determine course correction manoeuvres. Otherwise it will mean LOC (Loss Of Crew).

Many of these items will also apply to other AG solutions. Several could be addressed by using a rigid telescopic truss instead of a tether, but that would have a high mass and therefore be an even more expensive solution. There’s got to be a better way! The rest of Mars Direct is comparatively much simpler.

Note that Mars Direct does not use AG for the return trip, but only the outbound portion of the mission. Therefore the crew still must spend about 6 months in microgravity.

AG in DRA5

DRA5 doesn’t commit to using AG for a long-stay architecture. It only states that AG should be used if a short-stay mission class is selected, due to the longer time (~600 days) spent in space.

Microgravity in Blue Dragon

AG is not used in Blue Dragon. The crew will travel through space for about 8-12 months in microgravity. There are several reasons for this decision.

Cost

One of the main obstacles to sending humans to Mars (other than concerns about microgravity health effects) is cost. The cost of a Mars mission is driven by two main factors:

  • The amount of mass to launch and send to Mars, which determines fuel requirements, rocket sizes, number of launches, and size/mass of major components.
  • The complexity of the architecture and hardware, which drives cost of development time, including engineering, manufacturing and human resources.

As the above review of the AG solution presented in Mars Direct shows, using a tether and centrifugal force to produce AG requires greater mass in several ways:

  • Mass of the tether.
  • Mass of additional fuel for RCS.
  • A spacecraft designed for a gravity environment must be bigger/heavier, or have less features, than one designed for microgravity.
  • The spacecraft must be more complex (see below), which will also make it heavier.

It increases complexity in numerous ways:

  • Navigation systems.
  • Solar panels.
  • Communications.
  • RCS.
  • Major manoeuvres: TMI and MOI (Mars Orbit Insertion)
  • Tether design and operation.
  • EDL.

It’s difficult (at least, for me) to quantify exactly what the additional cost would be to implement an AG solution like the one proposed in Mars Direct. However, what we can assume is that Blue Dragon will likely cost billions of dollars in hardware and development costs. While AG will surely be a feature of future missions once launch costs decrease and launch vehicle capabilities increase further, omitting it from at least the first few will greatly reduce costs without greatly increasing risk.

Risk

Although you could say that AG reduces the risk that the crew might reach Mars or Earth in less than tip-top physical condition, the Mars Direct solution adds other risks, such as:

  • Hab crashing into counterweight.
  • Tether breakage.
  • More complex course manoeuvres could send the spacecraft in the wrong direction.
  • Harder to track and communicate with spacecraft.
  • More risky/complex EDL.

More risk means more failure points, potential emergency situations, abort modes, development costs, and training.

The risks associated with microgravity health effects, however, are comparatively well-known and easy to address.

Additional reasons

  1. The AG solution described in Mars Direct is only valid for the outbound trip anyway, so it’s not a complete solution. Maybe they’ll get to Mars well-adapted to Mars gravity, but on return to Earth they will be in almost the same condition as if no AG was provided at all.
  2. The Mars Direct AG solution only produces Mars-level gravity. This is still a reduced-gravity environment and therefore the crew will still experience some degree (perhaps ~62%) of the usual effects of microgravity. You could say that overall, this idea only goes about 19% (38% * 50%) towards addressing the microgravity problem.
  3. By this stage we have many human-years of experience with microgravity thanks to the International Space Station, Mir, and other space stations and missions before that. Similarly, we have experience with many astronauts and cosmonauts fully recovering from their time in microgravity. Commander Chris Hadfield returned a few days ago from the ISS after 5 months in microgravity, and is experiencing dizziness and weakness. However, he is in good humour, giving interviews, and reports feeling better “by the hour”.
  4. By constructing Abeona (our MTV) on orbit rather than sending a hab on TMI from a single launch, Abeona‘s cruise stage can be provided with additional fuel to reduce the total time spent in space to less than one year and perhaps even less than 10 months.
  5. NASA and JAXA successfully demonstrated in 2011 that osteoporosis drugs can be used to mitigate bone density loss. Without the drug Fosomax, the average bone density loss was 7% in the femur and 5% in the hip; with the drug, the loss in the femur was only 1%, and hip bone density actually increased by 3%.
  6. If the crew travel to and from Mars in the same vehicle and in the same gravity environment, the return trip will be much more comfortable, because they’ll already be used to Abeona and will have made it homely. Personal solutions and routines for dealing with microgravity will already have been developed during the outbound trip.
  7. On arrival at Mars, it’s estimated that it will only take 1-2 weeks at the most for the crew to adapt from microgravity to Mars gravity. Since they have 18 months on the surface, this is only 2.5% of the total time on Mars and quite acceptable. The most important thing is to design the architecture so that the crew will not be required to do any strenuous work during the first few weeks. This is exactly what we’ve done with Blue Dragon, in which the hab is landed 26 months earlier, powered up, checked out and inflated.
  8. Considering the current state of medical research, especially in nanotechnology, prosthetics and replacement organs, the exponential pace of technological development, and the hero status of the first Mars astronauts, it’s safe to say that in 20-30 years, in the very unlikely event that that do arrive back at Earth in a really messy, unrecoverable state of health, there will be a multitude of techniques to restore them to full health, strength and mobility.

Conclusion

The conclusion is hopefully clear: attempting to implement an AG solution for an early stage H2M mission simply isn’t worth it.

Benefits of travelling to Mars in microgravity:

  • More compact and/or full-featured MTV (Mars Transfer Vehicle).
  • Cheaper.
  • Safer.
  • Simpler.
  • Microgravity is fun.

There are, of course, other ways to create AG, for example, using a spinning cylinder, or by separating the MTV and a counterweight with a fixed steel truss; however, these each come with their own similar set of drawbacks. The most important are cost and complexity. For the first few human missions, we’ll be just fine without AG.

Exercise

While not a complete solution to the effects of microgravity, the most important strategy is daily exercise.

Resistance training

As a qualified personal trainer and lifelong fitness and bodybuilding enthusiast, I’m fortunate to have some specialised knowledge about resistance training, also known as strength training. The simple fact is that the human body responds to loading. If you unload it – for example, by spending time in microgravity – the body will adapt by losing muscle and bone mass, as this isn’t needed to carry the weight of the body. If you load the body – for example by lifting weights several times per week – the body will adapt by increasing muscle and bone mass.

Although there’s a vast body of knowledge around fitness and bodybuilding, once you trim away all the cruft there are really only a few basic principles:

  • The body responds to loading. This is a function of two things:
    • The amount of weight it’s loaded with. The more weight the body is loaded with, the more it will be forced to grow stronger.
    • The amount of time it’s loaded (also called “TUT” or “time under tension”). The more time the body spends loaded, the more it will be forced to adapt.
  • Nutrition is a critical factor, especially protein. Protein should be the primary macronutrient in the diet, as it provides the building blocks (amino acids) to synthesise new muscle tissue for growth and repair. A balance of other nutrients is also essential: complex carbohydrates for energy and recovery, minerals for muscle function, essential fatty acids (EFA’s), vitamins, and lots of water.

Someone can get started in bodybuilding knowing just two things: lift weights, eat protein.

Strength training involves performing a range of exercises to train all the muscles in the body. But is there an exercise that simulates loading due to gravity? Yes, and this exercise is well-known to bodybuilders as being the number one exercise for loading and therefore building almost the entire body: squats. Squats are called the king of exercises because they load the entire load-bearing kinetic chain of the body – the same muscles used in standing, walking, jumping and running. Squats load the body in almost the same way as normal gravity (vertically downwards), but with a greater load. They will surely be revealed as the number one exercise for reversing the deconditioning effects of microgravity.

The intention for Blue Dragon is for the crew to spend 1-2 hours per day doing strength training. Not only squats, because that would be a bit boring and would lead to over-training, but all the so-called “Big 5” exercises: squats, deadlifts, chest press, shoulder press, and chin-ups.

Spending only 5% of each day with the body partially loaded may not seem like enough to offset the effects of microgravity, unless the body is loaded with a larger force than normal Earth gravity. This is, of course, what we do in the gym in order to stimulate muscle growth. By loading the body with heavy weights during training, it becomes stimulated to increase muscle mass. We can use the same principle in space.

Usually when we talk about resistance or strength training, the goal is muscle growth and fat loss. But one of the major problems with microgravity is loss of bone density. Strength training will help with this, too. Research shows that resistance training produces noticeable increases in bone density, and is therefore sometimes recommended for women suffering from osteoporosis. Actually many other conditions have been shown to benefit from strength training, including cardiovascular disease, diabetes, and high blood pressure.

But how can we lift weights in microgravity? Resistance doesn’t have to come from lifting lumps of iron against gravity. There’s plenty of commercial gym equipment based on hydraulics, which will work perfectly well in a microgravity environment.

Yoga

There’s something else we can do in microgravity to stay fit: yoga. Yoga is well-known to have a huge range of benefits for the entire body. Can we do yoga in microgravity? Yes, as long as we have space. Also, yoga positions that emphasise balance won’t apply in microgravity. But flexibility, breathing, clearing the lymphatic system (detoxing), releasing stress stored in the spine and muscles, and the many other benefits of yoga can be gained.

Cardio

Because it’s easier to push blood around the body without gravity, the heart doesn’t have to work as hard. This can cause a decrease in heart mass. But this can be mitigated by regular cardiovascular activity. The heart must be exercised like any other muscle, but it’s exercised differently, using cardiovascular exercise instead of resistance training. The heart rate must be elevated. Although this is achieved for intermittent periods with strength training, cardiovascular exercise serves to sustain an elevated heart rate for longer periods.

EHA (Extra Habitat Activity) on Mars

While on Mars for 1.5 years, the crew will be engaged in considerable additional exercise in the form of regular, perhaps daily, EHA. This will frequently last several hours, perhaps all day in some cases, and during this time they’ll be wearing a MSS (Mars Surface Suit) also known as a marssuit.

The marssuits will probably weigh about 50kg. The spacesuits used by the Apollo astronauts weighed about 100kg, but in the lunar gravity, which is only about 1/6 of Earth’s, they felt like only about 17kg. This is almost what a full traveller’s backpack weighs, and perhaps half what a soldier’s backpack weighs. It’s hard to imagine spending hours walking around and doing hard-core science and exploration on Mars while carrying more than around 20kg, which is why one of the goals for H2M is a marssuit design of 50kg or less. A 50kg marssuit will feel like 19kg on Mars.

The average human weighs 62kg. With a marssuit on, an astronaut on Mars will weigh about 110kg – but they’ll feel like they weigh a total of about 42kg. Thus, they’ll be carrying about 2/3 their normal weight instead of only about 1/3. Going on EHA will be an important part of the necessary physical conditioning to mitigate bone and muscle atrophy. And let’s be honest: if you have a choice between going EHA on Mars and doing squats in the hab, which would you choose?

Blue Dragon daily program

The health and fitness program for the Blue Dragon crew will be something like this:

  • PT 6 days, rest 1 day.
  • Morning exercise: yoga or cardio (alternating days).
  • Afternoon exercise: resistance training or EHA.
  • Appropriate osteoporosis drugs and supplements (e.g. calcium) to mitigate bone loss.
  • A high protein diet to minimise muscle loss and support muscle growth and repair.
  • Plenty of minerals, especially calcium and magnesium.
  • Plenty of water, and a healthy balanced diet.
  • Sufficient sleep.
Architecture

Blue Dragon: Crew Selection

Crew size

The Mars Semi-Direct and NASA DRA architectures specify a crew of six, although the Mars Direct and Mars-Oz architectures require only four. Although it may be possible that a smaller crew – even as small as 2 people, as is being proposed for the Inspiration Mars flyby – may theoretically suffice, Blue Dragon is currently intended for six. There are a variety of reasons for this:

  1. It’s about as large a crew as we can handle while keeping the mission achievable and affordable.
  2. A crew of six permits a dedicated crew member for the most crucial functions, while also allowing for a degree of redundancy in skill coverage.
  3. The NASA DRA, on which Blue Dragon is based, has been designed around a crew of 6. The assumption here is that the NASA DRA has had more thought put into it than any other Mars mission architecture, and we can benefit by leveraging this work.
  4. A single Bigelow Aerospace BA-330 module, which we’re planning to use for the Abeona (the MTV, or Mars Transfer Vehicle), is designed to support 6 people.
  5. The SpaceX DragonRider capsule, which we’re using to ferry the crew between Earth/Mars surface and orbit, is designed for 7 people. Therefore, it should be big enough for 6 crew in spacesuits.
  6. It permits flexibility with team configurations.

Point 4 is important. If our intention is to use a BA-330 for Abeona, and it will support 6, then to design the mission for less would be inefficient. What we have to check here, however, is the volume that will be required for stores; however, 330m3 should be ample, considering that the bare minimum volume per person considered necessary for a space mission is just 10m3.

Why not five, or three, or seven people? The Apollo crews had three members. There’s one main advantage to having an odd number of people in the crew: it means that you never get a tied vote. However, it also means you can’t use the buddy system:

The Buddy System
The buddy system is something kids learn in school, but is also a pretty good idea for H2M (Humans to Mars) missions. It means, everyone works in pairs. Your partner is your “buddy”, and it’s their job to watch your back and make sure you don’t get shot by a laser, step on a scorpion, fall into a collapsed lava tube or forget to take your meds, as the case may be. In turn, you do the same for them.

Naturally, the crew will not always be able to all work together. However, for safety and psychological reasons we may want to avoid any crew member being left alone; at least, they shouldn’t work alone.

Within the buddy system, six people can be organised as:

  • Three teams of two
  • Two teams of three
  • One team of four and one of two

This flexibility can be useful when organising shifts, EVAs, and chores, and it means no-one works alone and safety is optimised.

With a three person crew, either the three would always stay together, or people would work alone, compromising safety. With a four person crew, the only team configuration available is two pairs of two. While this might be acceptable, we have capacity for more and a crew of six offers greater advantages.

I’m not saying a crew of 3 wouldn’t work, by the way. Apollo crews were 3 people, and Apollo was the most successful space program in history. But we’re not talking about 3 days on the Moon but 1.5 years on Mars. There is a lot more to do, and we need the extra people.

International astronauts

Perhaps somewhat idealistically, it’s my view that Mars is for all humanity; therefore, the crew should ideally be international. My goal for the Tiw Program is to develop it within an international Mars Consortium.

The first H2M mission will be the one history remembers, and it’s my opinion that the four major space agencies with human spaceflight capability should be represented, each by one astronaut:

  • United States
  • Russia
  • Europe
  • China

Actually, the fact that only four countries have human spaceflight capability could be put forward as a possible reason for having a crew of only four. It seems nice and neat. But it’s not a great reason.

The remaining two slots would represent “the rest of the world”, and would be selected from candidates from Japan, India, Canada, Brazil, New Zealand or elsewhere. As to who gets selected, this will probably result from a balance between who are the best candidates, and which countries will pony up the dough to support the mission.

Astronaut roles

The crew on this mission will be required to fill a large number of occupations; in fact, far more than six. Furthermore, all occupations are so crucial to the mission that they require redundant backups. Therefore each astronaut on the mission must be trained in multiple roles.

The crew is fundamentally comprised of three engineers plus three scientists:

Flight Engineer/Pilot/Commander

This person will be responsible for understanding, operating and maintaining the habitat and various spacecraft, liaising with Mission Operations on Earth, and making executive decisions.

Colour:  White 

Mechatronics and Communications Engineer

Mechatronics engineering is uniquely multi-disciplinary, combining mechanical, electronic, computer and software engineering. Since much of the hardware used in the mission will be computerised, robotic or mechatronic in nature, it will be invaluable to have a crew member that can understand, program and repair such equipment. This role will include responsibility for all computers and mechatronic hardware, including flight computers, on-board computers in the rover, robotic arms, multimedia/web servers, personal computers, and more. They will also be responsible for all communications hardware used in space and on Mars.

Colour:  Blue 

Chemical Engineer

This person is responsible for operating, maintaining and repairing all chemical engineering hardware in the habitat and various spacecraft, including fuel systems, ISRU (In Situ Resource Utilisation) systems, life support and environment control systems, waste disposal systems and plumbing.

Colour:  Purple 

Planetary Scientist

This role combines geology, planetary science, astronomy and cartography. On the surface of Mars they will study areology, areomorphology, areochemistry, areography, etc., and in space they will perform Earth, Mars and astronomical observation. They will be responsible for any telescopes used in space and on Mars.

Colour:  Red 

Biologist

This role combines astrobiologist and horticulturalist, and will include searching for and (if found) examining extant life on the surface of Mars, and conducting experiments (for example, with food production) in Abeona and in the greenhouse on Mars.

Colour:  Green 

Medical and Safety Officer

The main responsibility of this person will be to keep the crew alive and healthy. This important role combines ship’s doctor, personal trainer, psychologist, and safety officer. It will include monitoring crew health and effects of micro-gravity and radiation, pushing fellow crew members through daily exercise routines, providing nutritional advice, administering medications and treatments, monitoring psychological health of the crew and providing counselling if needed, monitoring solar flares and conducting safety drills, and developing safety protocols and ensuring they’re followed.

Colour:  Yellow 

Note: If it is considered necessary to reduce the crew size, one idea would be to combine the Biologist and Medical Officer roles, since these roles overlap in skill-set and knowledge to some degree. However, this would be quite a lot for one person to take on, even a Mars astronaut.

Journalist

When first designing this crew, I was tempted to include a dedicated journalist or multimedia engineer, whose responsibility would be documentation and communications, including photography, videography, blogging, interviews and other forms of reporting. This would tremendously valuable to an H2M mission, as it will greatly increase engagement with the public (i.e. viewing audience) on Earth. This will help to justify the cost of the mission, improve revenues (if that should be important), and generate a higher volume of feedback and good wishes for the crew, thus improving morale and reducing feelings of isolation.

However, as ideal as it might be to have a dedicated journalist, it is hard to justify against the other more crucial roles. The alternative, which might in fact produce a better result if executed successfully, is to train all crew members in basic journalism. Another approach would be to assign journalism duties to the Planetary Scientist and/or Biologist during the space travel stages of the mission, since they may not be able to do much science during that time. The two scientists could share the responsibility once on the surface, or all the crew members could engage in daily or weekly reporting of their individual activities.

Colour coding

Once the crew has been selected, they are each assigned a unique, distinct colour, which is theirs until the end of the mission. These colours are used for everything that belongs to that astronaut – their bunk, spacesuit, special meals, clothes packs, towels – everything. Everyone in the crew will learn everyone’s colours.

Apart from the advantages of not mixing up your towel or your piss funnel with someone else’s, one of the primary advantages of having distinct spacesuit colours is that it will be easy to identify who’s who during EVA, when it will be hard to see each other’s faces or bodies. Brown, orange and pink are excluded due to similarity with local colours on the Mars surface. Red should be ok, since, despite Mars being known as the “red planet”, there’s not a lot of actual red in the landscape, and there should still be enough contrast with the ochre shades of Mars. Black spacesuits would not be a good choice for a spacewalk!

White Unique colour, comprised of all others combined. Associated with purity and kindness, it belongs to the mission commander.
Blue The colour associated with communications belongs to the mechatronics/communications engineer.
Purple The colour of magic and alchemy belongs to the chemical engineer.
Red As we’re going to the red planet, this colour belongs to the planetary scientist.
Green The colour of life and growth naturally belongs to the biologist.
Yellow The colour for happiness and safety belongs to the medical/safety officer.
Architecture

The Mars Surface Hab (MSH, or “the hab”)

The Mars Surface Habitat, or, more simply, “the hab”, is a custom-built piece of hardware designed to accommodate, ideally, a crew of 6 astronauts on the surface of Mars. It must therefore include cabins, common areas (kitchen/dining), laboratories and other work areas, ECLSS (Environment Control and Life Support Systems), waste-disposal, heating, lighting, cooking and electrical systems.

The current intention is for the hab to also include ISRU (In Situ Resource Utilisation) equipment capable of extracting water, oxygen and nitrogen from the Martian atmosphere. These will be used to maintain water and air supplies for the crew, compensating for losses due to leakage, inefficiencies in recycling systems, airlock usage, and possibly other factors. It will therefore also include appropriate tanks to store sufficient quantities of these fluids.

The hab may include inflatable modules. If possible, these will be inflated using oxygen and nitrogen obtained from the Martian atmosphere during the 26 months between arrival of the hab and arrival of Alpha Crew.

Unlike Mars Direct, DRA5 or the Mars-Oz architecture, in Blue Dragon the hab is landed uncrewed for reasons of improved safety. It is to be sent to Mars at approximately the same time as the MAV (Mars Ascent Vehicle) and landed nearby.

On arrival at Mars surface:

  1. The power system (solar and/or nuclear) will be activated.
  2. Doors containing inflatable modules will open.
  3. The ISRU unit will be activated and harvesting of O2, N2 and H2O (oxygen, nitrogen and water) from the atmo will commence.
  4. The inflatable modules will inflate while the water tanks fill.
  5. Once the hab is inflated, the O2 and N2 tanks will also fill.

A completely uneducated guess at the cost of development of the hab will be around $2-5 billion. This is based on comparison with MSL (Mars Science Laboratory, also known as Curiosity), which, so far, has cost an estimated $2.5B. While the hab is more complex than Curiosity in certain important ways (e.g. it must keep people alive), it is simpler in others (e.g. it doesn’t have to move). Furthermore, the intention is for private contractors to develop and manufacture the hab, rather than a large agency such as NASA, which should, in theory, significantly reduce costs.

Design

For the basic form of the hab, previous architectures such as Mars Direct and DRA5 have primarily focused on a vertical cylinder; the so-called “tuna can” model:

Tuna can-style Mars hab
Tuna can-style Mars hab

This form of habitat is usually assumed to have a diameter of around 8 metres, which will fit inside the fairing of an SLS (Space Launch System) heavy lift rocket.

However, this vehicle is yet to be developed, and I would prefer that this architecture be independent of NASA-built rockets. You may well ask: Why? The answer is one word: Ares.

A very brief history lesson:

After the Vision for Space Exploration was announced in 2004, NASA began a new program of hardware development called the Constellation Program, which included two new rockets: Ares I and Ares V. Ares V was designed as a HLLV (Heavy Lift Launch Vehicle) with a 10m diameter – perfect for a tuna can-style Mars hab.

Unfortunately, despite a faked Ares I demonstration, development of the Ares rockets was shelved. A new family of rocket vehicles called the Space Launch System is now being developed instead. The diameter of the SLS fairing will be 8.4 metres, which, again, would be suitable for a tuna can Mars hab.

However, in light of what happened with the Ares vehicles, the fact that NASA pulled out of ExoMars due to cost overruns elsewhere, and because of the budget sequestration currently being implemented in the US, I feel that it would be a mistake to believe that the SLS will definitely be built. Of course, I hope it will, because we really need heavy lift capability and that nice, wide payload fairing. I just don’t want to rely on it. SLS could be cancelled just as easily as Ares was by the next administration.

There is hope for heavy lift. SpaceX is apparently planning to develop a super-heavy lift vehicle called the Falcon X, which will also have a fairing diameter of about 8m. Based on their track record, I believe SpaceX will achieve this goal. However, it could be years away, and if we say we definitely need that rocket then it’s back to the waiting game.

The real question is – do we actually definitely need it? Do we really want to wait around until someone builds a rocket with a big enough fairing? Or can we make do with what we have?

For now I’ll continue to assume we’ll have access to the Falcon Heavy in the near future, especially since I’ve seen one under construction at SpaceX. The dimensions of the the Falcon Heavy fairing are the same as the Falcon 9, as follows:

Falcon Heavy fairing dimensions
Falcon Heavy fairing dimensions

As you can see, there is only a 4.6m diameter available.

It would be hard to imagine a good vertical cylinder hab configuration with such a narrow diameter, even if you designed it to be the full height of this fairing. Perhaps it could be done. Respectable individuals such as Robert Zubrin have already looked at doing H2M (Humans to Mars) with just a Dragon capsule, which obviously fits in this fairing. It would be smaller than a Tokyo apartment, and the mission would probably require the crew size to be reduced to two, but, theoretically it could be done.

Is there another way? Jonathan Clarke and David Willson from Mars Society Australia have studied horizontal Mars habitats based on a bent biconic design:

MarsOz bent biconic hab
MarsOz bent biconic hab

This habitat is 18 metres long, with a diameter of 4.78 metres, which will almost fit inside a Falcon Heavy fairing. It’s designed to accommodate a crew of 4. This approach offers several advantages other than dimensions and orientation, which are discussed in the paper A Practical Architecture for Exploration-Focused Manned Mars Missions Using Chemical Propulsion, Solar Power Generation and In-Situ Resource Utilisation by Willson and Clarke:

  1. The biconic shape has a better lift-to-drag ratio than the traditional vertical cylinder, and is therefore easier and safer to land (especially important if people are in it).
  2. It can be lengthened by attaching additional sections, delivered separately.
  3. It permits longer cargo length (such as a rover).
  4. The loading ramp has a lower gradient, which is safer.
  5. It’s much easier to tow a shape like this into a good location. Vertical cylinders must stay where they land.

The above design will not fit within a SpaceX Falcon Heavy fairing. It’s a bit wide, much too long, and the bent biconic shape wouldn’t fit into the fairing.  But perhaps we can use it as inspiration for one that will fit:

Biconic Mars hab to fit Falcon Heavy
Biconic Mars hab to fit Falcon Heavy

In this sketch the hab is shown fitting as snugly as possible within the fairing, implying that thrusters, legs, EDL (Entry, Descent and Landing) hardware, etc., are set into the hab shape. The blue lines show the floor and ceiling of the liveable volume – the sections above and below that would be for equipment and storage.

This volume is probably still slightly small if we decide to stick to our desired crew size of 6. There are a couple of things we can do:

  1. We can reduce the crew size.
  2. We can send a few of these to Mars, and possibly connect them up.
  3. We can add inflatable modules.

This third idea has recently been developed by Polish engineer Dr. Janek Kozicki, whose design concept is based on the 8m diameter hab described in the DRA5, designed to fit within the payload fairing of the SLS:

MSH with inflatable modules
Hab with inflatable modules

As you can see, the addition of 3 inflatable modules to the central hab significantly adds to the total pressurised volume. This is an innovative solution with considerable value, especially when you consider that each Falcon Heavy launch costs $128M. This way we may be able to keep our preferred crew size of six.

The most obvious downside of using inflatable modules is that they provide less protection from harmful radiation. Whereas you could pile sandbags on top of the solid metal hab, that may not be practical with the inflatable modules. But this problem is probably solvable.

The next question is, can we adapt this concept to a horizontal cylinder? Well, of course. Here’s a thoroughly amateur Photoshop drawing to illustrate:

Blue Dragon MSH with inflatable modules
Blue Dragon hab with inflatable modules

After landing, the hab is remotely activated from Earth, causing the inflatable section of the habitat to inflate. This is perhaps most easily achieved using compressed air. However, a far more interesting option is to manufacture the air from local resources (ISRU) and inflate the hab gradually. Since we are sending the hab one launch window earlier than the crew, we will have about 26 months in which to inflate the hab and test its various systems.

More research needs to be done into the nature of the air-making unit, which would harvest oxygen and nitrogen from the Martian atmosphere. We need to know if we can make enough air in the time available, how much the unit will weigh, and its energy requirements.

If we can develop a realistic and affordable hab around this concept, it means we’re one step closer to Mars – without having to wait for SLS or Falcon X.

There’s still one very important thing to consider, though: mass.

Architecture

Blue Dragon: Overview of Major Hardware Components

SpaceX Falcon 9

The Falcon 9 is a successful flight-tested rocket noted for being the rocket that enabled SpaceX to become the first commercial company to visit the ISS (International Space Station). A Falcon 9 can carry 13150kg to LEO (Low Earth Orbit). Within the Blue Dragon architecture the Falcon 9 is used to launch all Dragon and DragonRider capsules to LEO.

The fairing and payload dimensions are shown below:

Falcon 9 fairing dimensions
Falcon 9 fairing dimensions

It is currently estimated that a total of three Falcon 9 launches will be required for a complete Blue Dragon mission:

  1. Pre-mission: Launch fitout crew to Abeona.
  2. Beginning of mission: Launch the crew to Abeona so they can transfer to Abeona prior to TMI (Trans Mars Injection).
  3. End of mission: Launch DragonRider to Abeona on arrival back in Earth orbit, so the crew can transfer to the DragonRider and descend to Earth surface.

At current prices of $54M per launch, this will cost $162M.

SpaceX Falcon Heavy

The Falcon Heavy promises to be the most powerful rocket in the world, second only to the retired Saturn V rocket that launched Apollo astronauts to the Moon. A Falcon Heavy can deliver upwards of 53t to LEO.

In the Blue Dragon architecture, the Falcon Heavy is designed to launch the primary components to Mars: Abeona, the hab, the MAV (Mars Ascent Vehicle) and the cargo Dragons.

While the Falcon Heavy can deliver a much larger mass to LEO, it has the exact same payload dimensions as the Falcon 9, as shown above. Each of these major components (or their sub-sections) must fit within these dimensions.

It is currently estimated that a total of five Falcon Heavy launches will be required for a full run-through of the Blue Dragon architecture:

  1. Launch the MAV to Mars.
  2. Launch the hab to LEO.
  3. Launch the hab cruise stage to LEO.
  4. Launch first cargo Dragon (MCM-1) to Mars.
  5. Launch second cargo Dragon (MCM-2) to Mars.
  6. Launch pieces of Abeona (the Mars Transfer Vehicle) to LEO.

At current prices of $128M per launch, this is $640M.

Mars Transfer Vehicle (MTV, or “Abeona“)

This is the space vehicle that will carry the crew to Mars and back. It is partially constructed and fuelled on orbit, and is not designed to ever land anywhere.

Abeona as currently envisaged will be based on a single Bigelow Aerospace BA-330 module, assuming, for now, that this will be large enough. A BA-330 is designed to support up to 6 people, which we will have; however, for an H2M mission it must also stock provisions for 6 people for at least 1 year, and perhaps as much as 1.5-2 years assuming we wish to provide the option to abort from Mars orbit. It may be necessary to connect two BA-330 modules together to provide double the pressurised volume and thus accommodate provisions. Further calculations are required.

The MTV is called Abeona, partly because a ship should have a name, and partly to reduce acronym overload. Abeona was the Roman goddess of journeys, who watches over children leaving home for the first time. Her name comes from the Latin verb abeo, “to depart, go away, or go forth”.

The BA-330 has the following attributes, when fully inflated:

20-23t mass

9.5m long

6.7m diameter

330m3 pressurised volume

The BA-330 module will be launched to LEO with engines, fuel and additional cargo and equipment using a Falcon Heavy. A single Falcon Heavy is capable of placing 53t in LEO, thus permitting up to an additional 30t of hardware to be launched with the BA-330. The full manifest is yet TBD (To Be Determined) but will likely include some or all of:

  • Engines.
  • Sufficient fuel to get to Mars and back.
  • Panels, furniture, etc. for internal fitout.
  • Gym, lab and medical equipment.
  • Food and water for 1-2 years.

After delivery to LEO, the BA-330 is inflated. The additional cargo will be tethered to the BA-330.

A fitout crew is subsequently launched via Falcon 9 + DragonRider to Abeona to complete construction. Interior construction of rooms, including cabins, laboratories, control room, gym/medical room, storm shelter, food/water storage, etc., will be completed. If necessary, additional supplies can be delivered to Abeona via Falcon 9 + Dragon.

Mars Surface Habitat (MSH, or “the hab”)

This is a custom-built piece of hardware designed to accommodate a crew of 6 astronauts on the surface of Mars. It must therefore include cabins, common areas (kitchen/dining), laboratories and other work areas, ECLSS, waste-disposal and power systems.

The current intention for the hab is that it will also include ISRU (In Situ Resource Utilisation) equipment capable of extracting water, oxygen and nitrogen from the Martian atmosphere, in order to maintain water and air supplies for the crew and compensate for losses due to leakage, recycling, airlock cycling and other factors. It therefore includes appropriate tanks to store sufficient quantities of these fluids.

The hab will include 2 inflatable modules, inspired by the design by Dr. Janek Kozicki. These will be inflated using oxygen and nitrogen obtained from the Martian atmosphere during the 26 months between arrival of the hab and arrival of Alpha Crew.

Unlike Mars Direct, DRA5 or the Mars-Oz architecture, the hab is landed uncrewed for improved safety. It is to be sent to Mars at approximately the same time as the MAV and landed nearby (within 1 km). On arrival at Mars surface:

  1. The hab will be activated (battery power) and checked out.
  2. The power system (solar and/or nuclear) will be activated.
  3. The three doors containing the inflatable modules will open.
  4. The ISRU unit will be activated and harvesting of O2, N2 and H2O from the atmo will commence.
  5. The inflatable modules will inflate while the water tanks fill.
  6. Once the hab is inflated, the O2 and N2 tanks will also fill.

Estimated maximum cost of development of the hab is $3B. This is based on comparison with MSL (Mars Science Laboratory, also known as the Curiosity rover), which has cost an estimated $2.5B. While the hab is more complex than Curiosity in some ways, it is simpler in others. Furthermore, the intention is for a private contractor to develop and manufacture the hab rather than a large agency such as NASA, which should significantly reduce costs.

Mars Cargo Module (MCM or “cargo Dragon”)

For this option we will use 1-3 SpaceX Dragon capsules optimised for landing on Mars, and capable of delivering 3-6t of cargo each.

A version of the Dragon capsule optimised for Mars landing is already being developed for the Red Dragon mission. This important technical development will enable us to safely and repeatably land several tonnes at a time on Mars, which is a key enabling capability for human exploration and settlement of Mars.

The development cost of the cargo Dragons may therefore, in theory, be $0. In fact, this may even be a COTS (Commercial Off-The-Shelf) component by the time of the mission. Once the ability to land Dragons on Mars is more fully mature, the cost is likely to be fixed (based on SpaceX behaviour to date), and probably less than ~$40M each.

This is much cheaper than the cost of developing an entirely new custom vehicle; yet the benefit to the crew of a few additional tonnes of cargo, including spare food, water, backup hardware, etc., will be significant. It may be worthwhile sending several cargo Dragons in order to fully support the crew for their 1.5 year surface stay.

There are several advantages to sending multiple capsules instead of one larger one:

  1. If one cargo capsule crashes, it’s cheaper to replace.
  2. It’s easier and safer to land smaller masses on Mars.
  3. It provides additional practice landing Dragon capsules on Mars.

Pern-1 (Earth ascent/Mars descent DragonRider)

Pern-1 is a DragonRider capsule optimised for landing on Mars, and capable of delivering 6 astronauts wearing marssuits to Mars surface.

As mentioned, a SpaceX Dragon is currently being developed for Mars landing. A DragonRider is simply a Dragon with crew configuration, i.e. it has seats inside. A standard DragonRider is configured to carry 7 astronauts without suits; however, for the purpose of Blue Dragon, Pern-1 will be configured to carry 6 astronauts wearing suits. This may require slightly larger seats, depending on whether the suits are gas-pressurised or MCP (Mechanical Counter-Pressure).

Why are the DragonRiders in this mission called “Pern”? It comes from a series of sci-fi novels by Anne McCaffrey called Dragonriders of Pern. Pern is the name of the planet where the series is set. Again, names are given to the DragonRider capsules to reduce acronym overload.

Pern-2 (Earth descent DragonRider)

Pern-2 is a DragonRider capsule that will be launched from Earth via Falcon 9 after Abeona has complete EOI (Earth Orbit Injection) and is safely back in LEO. The crew will transfer to Pern-2 and return to Earth.

It’s assumed, for now, that by the time Pern-2 is required DragonRider capsules will have already been used several (or many) times to transport people from Earth orbit to Earth surface, whether from the ISS or other spacecraft. The capability is currently being developed to land Dragon and DragonRider capsules on solid ground rather than splashdown in the ocean, via the addition to the Dragon of eight SuperDraco thrusters. This feature should have been available for around 20 years by the time Alpha Crew is due to return.

The crew will land on solid ground at an appropriate location TBD, which will be somewhere that immediate medical assistance can be provided by space medicine professionals, and planetary protection mechanisms can be implemented effectively.

Architecture

Blue Dragon: Architectural Overview

Here is an overview of the Blue Dragon mission architecture.

This section refers to “Sagan”, the first base on Mars created through the Tiw Program. Note that Mars One may already have a base established by 2023 or thereabouts. It also refers to “Abeona”, the name of the MTV (Mars Transfer Vehicle).

The first crew to go to Sagan is called “Alpha Crew”. The second crew will be named “Bravo Crew”, and so on, following the international aviation alphabet. This pattern has been adopted in order to support clear radio communications between Mars exploration crews and Earth.

The location of Sagan is still TBD (To Be Determined).

This timeline does not, for now, entertain a potential overlap of Bravo mission with Alpha. In that scenario, if all goes well for Alpha Crew then Bravo Crew would be sent out in 2035, when Alpha Crew are on their way back. For now it’s assumed that we want to bring Alpha Crew safely back to Earth, fully completing the mission, before preparing to send another crew.

Phase 1 – Pre-Mission

  1. Select and train Alpha Crew.
  2. Develop and construct the MSH (Mars Surface Habitat), also known simply as “the hab”.
  3. Develop and construct the MAV (Mars Ascent Vehicle).
  4. Make any further modifications (if required) to Dragon and DragonRider capsules necessary for Mars landing.

Phase 2 − 2031 Launch Opportunity

  1. Launch the MAV, land it safely at Sagan.
    1. Remotely activate MAV.
    2. Self-contained thorium reactor is telerobotically driven some distance from the MAV, unrolling power cable behind it.
    3. ISPP (In Situ Propellant Production) unit in the MAV reacts H2 (hydrogen) with CO2 (carbon dioxide) extracted from Martian atmosophere to make LOX/LCH4 (liquid oxygen/liquid methane) bipropellant.
  2. Launch the hab, land it safely at Sagan.
    1. Remotely activate hab.
    2. Self-contained thorium reactor is telerobotically driven some distance from the hab, unrolling power cable behind it.
    3. Three exterior doors containing inflatable modules are opened.
    4. ISRU (In Situ Resource Utilisation) unit is activated and harvesting of O2, N2 and H2O (oxygen, nitrogen and water) from the atmo commences.
    5. Inflatable modules inflate with indigenous O2/N2, while the water tanks fill with indigenous H2O.
    6. Once the hab is inflated, commence filling the O2 and N2 tanks.
  3. Launch 2-3 (TBD) Dragons containing cargo to Mars, land them safely at Sagan.
  4. Build sections of Abeona, launch them to LEO (Low Earth Orbit), and complete construction on orbit.

 

MSH fully inflated (credit: Janek Kozicki)
MSH fully inflated (credit: Janek Kozicki)

Phase 3 − 2033 Launch Opportunity

  1. (TBD: Launch backup MAV, hab, cargo Dragons.)
  2. Launch crew in a DragonRider via Falcon 9, and dock with Abeona. The DragonRider remains docked to the Abeona en route to Mars.
  3. Abeona performs TMI (Trans Mars Injection) and flies to Mars on a minimum-energy transfer orbit for ~6 months.
  4. Abeona performs MOI (Mars Orbit Injection) and parks in Mars orbit.
  5. Crew descends from Abeona to the surface of Mars in the DragonRider, wearing spacesuits.
  6. On landing, the crew exit the DragonRider and transfer to the hab.
  7. The crew spends approximately 18 months on the surface of Mars, living in the hab.

Phase 4 − 2035 Return

  1. About one month prior to departure, commence systems checks of MAV and Abeona.
  2. Put hab in standby mode.
  3. Crew transfers to MAV on foot, in spacesuits.
  4. MAV launches from the Mars surface to Mars orbit, and docks with Abeona.
  5. Crew transfer from the MAV to Abeona.
  6. MAV undocks from Abeona and autonomously flies back to Sagan, following the same program that took it there the first time.
  7. Abeona flies back to Earth, again on a minimum-energy Hohmann transfer orbit for ~6 months.
  8. Abeona parks in Earth orbit.
  9. A DragonRider is launched from Earth and docks with Abeona.
  10. Crew transfers to the DragonRider.
  11. DragonRider carries crew to Earth surface.

Phase 5 − Post-Mission

  1. Alpha Crew go into rehabilitation to rebuild muscle and bone, followed by world tour.
  2. One or more missions to refurbish/upgrade Abeona in preparation for the next mission.
  3. Select and begin training Bravo Crew.
  4. Develop next generation hardware.
  5. Send more stuff to Sagan or a new location nearby.