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Probably 2040 before samples from Mars are returned safely, legally and are not likely to answer questions about astrobiology

The BBC has just reported that ESA signed a letter of intent to cooperate with NASA on a return sample of Mars (see Agencies aim to bring rocks from Mars). I hope this does not mean a change of focus for ESA from on-site searches to a sample return. This costly NASA program is more a demonstration of astrobiological technology than an astrobiology mission. It is not likely to solve any of the major questions in astrobiology, and yet if you return an unsanitized sample, there is so much involved legally and technically in ensuring that the Earth's environment is protected, that it is very unlikely that you are ready to return. . a sample for 2040. It may not be possible until 2050 or later.

Mars sample return concept – NASA credit

This is based on estimates of the probable time scale for installation by the NRC and in the Margaret Race study of the required legal processes. What makes the protection of Earth's environment so complex legally and in engineering terms is that until we know what life is on Mars, if necessary, they have to design a facility that can contain any assimilable form of Mars astrobiology. both. when the only life we ​​know is on Earth.

Now, if Mars were like Earth, if it had life everywhere, wherever there are organic elements, yes, astrobiologists would be enthusiastic about that mission, and unless it lands in a very cold dry desert, it would be tied to return some life in the sample. But Mars is different from Earth in many ways that make this simple scenario unlikely. First, it is predicted that it will be flooded with organics that fall from space in dust, meteorites and comets, which would overwhelm both current life and the few remaining traces of past lives, if they exist. On Earth, almost all places where there are organic, there are also past lives, or traces of past lives. On Mars, it is likely to be almost the reverse situation. In almost all places where there are organic elements, there may be no signs of life, past or present, only organic substances from space. If we do not find life on Mars immediately, this does not mean that the Mars biosphere is safe for Earth or that the Earth's biosphere is safe for Mars. It simply means that we can not assess what the effect of a biosphere collision will be until we can obtain more data.

It is expected that both past and current life will be very difficult to detect on Mars.

Current life may be present everywhere on Mars, but only in occasional fine spots of favorable brine here and there and occasional spores in the dust, or it could be restricted to particular places where conditions are more favorable. However, you can not rule out the possibility of long-lived spores in dust anywhere on Mars, protected from UV rays by iron oxides in the dust. The past life could be there again, but in deposits difficult to detect. Mars seems to have had at most brief warm periods of hundreds of thousands to a million years in the distant past. The traces of past lives can be in thin layers several meters underground and perhaps only in particular locations such as deltas or hydrothermal vents. Any past life that has been near the surface for hundreds of millions or billions of years has disappeared. A layer of organic compounds would be destroyed if the time it was exposed to cosmic radiation occurred recently, or soon after it was formed, or at some point in its geological history. Although ionizing radiation is not sterilized over thousands of years, over a period of time as short as one hundred million years, it would destroy all amino acids and surface nucleotides, most of which become volatile: water vapor and gases.

It would not matter much, if it were not for the cost and complexity of this mission. It might be useful to have a demonstration of low-cost technology. Chris McKay suggested that a mission to land on Mars pick up a handful of dust and return it, a couple of days on the surface, a simple low-cost mission. This is the only suggestion for a sample return from an astrobiologist that I have seen.

But no, it was not enough for them, they had to go all over the chant of a mission, traveling on Mars, trying to select a perfect set of samples by geological criteria instead of astrobiological and then falling in piles as caches shows. A decade later, another expensive tracking robot arrives to pick them up. It may be necessary to travel much of the same terrain again, but your only job is to collect the samples and return them to Earth. These samples, about half a kilogram in total, as expensive per gram as the most expensive diamonds, become the main things that NASA must show during two decades of superficial missions to Mars. Everything else through new missions to Mars had to be canceled by NASA to make this complex and costly mission possible. Not just for a decade, but for two decades.

Meanwhile, ESA has continued with its TGO capable of detecting traces of gases in the atmosphere at trace levels and its ExoMars capable of drilling. They seem to be moving towards a possible astrobiology mission in situ in the not too distant future. It would be so sad if this was diverted to focus on a demonstration demonstration demo of technology, which has proved to be a sinkhole for NASA's finances for Mars.

Finally, among all this, the planetary protection process for a sample return is so complex, legally and practically, that we would be lucky to see some of the samples cached by Mars 2020 before 2040, at least, not if the objective is to return non-sterile samples. It can not be done through COSPAR.

Maybe the idea is that the legal process can be swept away as it was for Apollo? If someone is thinking like that, the Margaret Race study makes it clear that such shortcuts are no longer allowed when it comes to legislation to protect the Earth's environment.

I will explain how I arrived at this estimate of 2040 as the earliest date, and you can take a look and see if you agree, or see a way to shorten it. But first, let's begin by explaining why astrobiologists consider it little more than a demonstration of technology for their discipline.


a constant influx of organic compounds from meteorites, comets and interplanetary dust. Sufficient for 60 ppm averaged to a depth of 100 meters (see page 10 of this document).

It does not have large deposits of organic matter from ancient life there or we would have already detected them. Young Mars was potentially as habitable as Earth, but not for long, compared to Earth. It may never have developed photosynthesis, and if it did, it may have happened too late in its history to deposit thick deposits before it became too dry for an abundant life.

There may be evidence of past life there, perhaps in ancient hydrothermal vents, perhaps in layers of mud, in deltas, there are many places to look for it. But it needs extraordinary drilling or luck, the right layer exposed by a meteorite or by wind erosion quickly enough, because the organic compounds are completely destroyed under surface conditions on time scales of a billion years. Most organic compounds passed on or near the surface will disappear some time ago, and will also be covered with organic elements that enter from interplanetary space.

There may also be life on present-day Mars, but it is on the edge of habitability. It is a planet that used to be very habitable, but even though it seems so dry and sterile there is now evidence of habitats where there may be persistent life in conditions that have remained marginally habitable for billions of years, with occasional moments when the The atmosphere thickens briefly and life spreads a little. Hundreds of millions of years in the future The Earth can get so hot that only a few heat-resistant life forms remain in the high caves of the mountains. Mars may be an example of a similar "Swansong Biosphere", but this time one in which life remains on a planet that has become so cold that life can barely survive there. It is likely that the most habitable areas on the surface of Mars are similar to some of the least habitable areas on Earth, our driest and coldest deserts. However, there may be life there.

Today Mars is not completely uninhabitable. It has confirmed liquid brines. They may all be too cold or too salty, but they may also contain livable brines and even fresh liquid water trapped under the ice in small amounts. Small quantities, however, a pool for a microbe as memorably expressed by Nilton Renno.

There could also be spores in the dust. Most of these suggested habitats are found at high latitudes. But there are also several possibilities of life in the equatorial regions. None of that can be stored in the memory of Mars 2020 and returned to Earth, except by chance, because you can not see it.

The reason why they say that this is a demonstration of technology and not an astrobiologically oriented mission is because there are no instruments capable of unequivocal detection of artificial life, and because they will not be drilled to seek life, which astrobiologists say that they are the main priorities.

If Mars 2020 were to find source rocks equivalent to the Tissint and ALH84001 meteorites on Mars, it would perforate them and return the nuclei as their priority objective.

You would expect the result to be as controversial as those meteorites and not solve any of the major astrobiological questions on Mars. And this is the best possible scenario since those rocks were sent to Earth from at least one meter below the surface.

Meanwhile, it would not be able to detect life among all the organic compounds in the meteorite. Astrobiologists have warned about this in many articles.

If the samples returned are not of great astrobiological interest, this will be what they predicted all the time.

Mars 2020 could choose to drill a sample to return a few cms next to an endolithic life patch on a rock and it is not known to be there, since it can not detect it. You could drive over biofilms a couple of cms below the sand you drive every day and again there would be no way of knowing it is there.

There could be near pristine organic from the old Mars two meters below its tracks and again I would not know this, and there would be no way to get to them if they knew.

The Mars 2020 sample tubes will not even be completely sterilized (they allow a small chance that there is a viable microbe in the tubes).

In my opinion, you should not call it an astrobiology mission. You can call it a geology mission, the samples would be great for geologists. As for astrobiology, it would be more accurate to call it an astrobiological technological demonstration. A demonstration to show how they could return stones of interest to astrobiologists at some point in the future after we ship in situ astrobiology instruments to Mars.

No problem to do it. That is of interest to astrobiology. The problem is that they have given priority to this sample return mission insofar as it is favored instead of numerous proposals for astrobiological instruments that probably will not fly until the return of the sample is completed.

It is very costly and difficult mission that you just do not have the budget to do an on-site astrobiological study of Mars at the same time as a sample return mission. It is a mission of two decades, Mars 2020 to cache the samples and their successor to return them, so the commitment to a return sample has meant the possibility of another 20-year delay before the first true astrobiological in situ missions to Mars from Viking in the 1970s. Currently, there is no one else that seems to carry out future on-site missions of astrobiology to Mars. And it's not something that can be done as a private mission at this time, no kickstarter or crowdfunding could raise enough to pay for an on-site lander on Mars, not yet.

The priority for the sample return mission has been set so high for NASA that they canceled a satellite that would be launched in 2022 using optical communication to enable 800 gigabytes of data returned per day from Mars. I would have allowed missions to Mars to send more data every day than all the data returned by the New Horizons Pluto flyby. This would have made a big difference in any mission to Mars, for example, high-resolution orbiter imagers could return hundreds of images per day, and surface scanners could return 3D panoramas of several gigabits several times a day. They canceled it on the basis that it is possible to perform a sample return mission from Mars without that capability. They decided that, since it was not essential for a sample return, and since the budget is tight (as it always is, of course), it is not their priority at this time.

For the mission, see

For the decision to cancel it, since it is not essential for the return of a Mars sample:


It is supposed to be a preliminary mission to verify that it is okay to send humans to Mars. But this mission would not prove that life on Mars is safe for our astronauts or for the Earth's environment. Nor would it prove that the microbes on Earth would not harm Mars.

He would not tell us even if there is life or not in the rocks that Mars 2020 drills. He could drill a sample cache from a few centimeters on the side of a life patch and not detect it.

You can not dig up the brine layer that is a few centimeters below its tracks while driving on the desert sand and possibly have biofilms that make it habitable for terrestrial life, and you will not be able to test the dust to see if it there are spores in it just below the surface.

Nor would it be sufficiently sterilized to approach any location on Mars that is suspected of having brines that could possibly be habitable.

It simply would not advance at all in our understanding of what the biospheres of Mars or the Earth could do to each other, if there is a biosphere of Mars, and if they collide.

To find that you need adequate detection of life in situ -not organic, or high relations c13 / c12 (the Tissint meteorite has that), not only chirality (carbonaceous chondrites have it). Astrobiologists emphasize that we need a dedicated set of life detection instruments with multiple simultaneous detection methods to control each other.

You can certainly do it. MOXIE alone, is an instrument that does nothing but generate oxygen, does not need to move, and in a mobile that does not need oxygen, it could be in any fixed landing module such as Insight. That mass of 15 kg, enough for 3-6 astrobiology instruments. The entire set of instruments in Curiosity is 75 kg and that is enough for more than a dozen or two dozen astrobiology instruments if the focus was put on astrobiology as for Viking and learning from Viking errors.

It's the only way. And the ability to drive and deepen.

Otherwise, all you're likely to find are organic compounds that bombard Mars from meteorites, comets, and interplanetary dust all the time


Planetary scientist Chris McKay, at NASA Ames, spans the worlds of astrogeophysics and astrobiology (he specialized in physics, has a doctorate in astrogeophysics, and since then has done a lot of work research in astrobiology). He is involved in the planning of the mission for Mars and you find his name in many of the documents in this thematic area of ​​extremophiles, life on Mars, analogue habitats of Mars, planetary protection and the search for life in our solar system. He has also written articles on terraforming of Mars.

Recommends that we take a sample of the soil of Mars to show what we can do and return it to Earth. Spend a day on the surface. Design the simplest and most economical way to return a sample of Mars, without Mars 2020, without rover. Just grab it and come back. In this interview, he says

" The first thing is to get a mission that takes out a lot of loose dirt, puts it in a box and returns it to Earth .If I were an astronaut, what? The discovery [by NASA’s Phoenix lander] of perchlorate on earth is a concern, it is toxic, and the second cause for concern is the fact that it took us so much by surprise, there was no prediction or The fact that it took us by surprise makes me wonder if there are other surprises on the ground … In fact, I would be surprised if there were no other surprises … Retrieving the earth is easy because it is everywhere You do not need a precision landing, you do not need a rover, you land, you grab some dirt and put it back on Earth, the terrain time on Mars could be one day. "

" … I have said for many years that the return The sample should be motivated by a combination of human exploration and science. The scientific community, I think, harms itself by adopting the attitude that there will be only a return of shows in the history of the universe, so it has to be perfect. And a sample return mission that does not become perfect should not be considered. I do not understand where the logic lies behind that. Let a first sample return a quick and easy sample, demonstrate the key technologies. It generates enthusiasm for the idea of ​​round trips to Mars. It would also make obtaining a second sample return easier, both programmatically and technically. That argument falls on deaf ears when I try and mention it in the community. "

One of his main concerns is that there is currently no alignment between NASA's Mars strategy and astrobiology. twice in the interview – near the beginning, and towards the end (the emphasis is mine):

"If we are going to look for life, let's look for life. I have been saying this to the point of exhaustion in the community of Mars. Geologists win without limits as they are entrenched in the Mars program. The favorite trick is to form a committee to decide what to do. The people who are put on the committee, of course, are people who are funded to study rocks. Then the committee recommends that we study rocks. They will say that these rocks will give us the context of how to look for life on Mars. So you say, well, that's not right. But the headquarters of NASA will say that they asked the scientific community and they told us that this is what we should do. It's like circulating. The reason the committee told you that is because you put together a committee of people who study rocks. It's almost a Catch-22. "

" … At this time, as far as I am concerned, there is no alignment between the strategy of Mars and astrobiology . What we have learned from studying Mars is that astrobiology has to go underground. You have to start drilling. Curiosity has a drill and had problems and now we are very cautious when using it. We have to go back to that horse and send a bigger drill. "

In that interview, I do not think Chris McKay is suggesting that his mission" retrieve dirt samples from Mars "is likely to be Astrobiological interest, rather sees it as of interest to understand the conditions on the land of Mars today for future surface missions, and human missions in particular, as it is believed that dirt includes chemicals harmful to humans. interest in astrobiology would be like a demonstration of technology to demonstrate that we can return a sample of Mars, at a later stage, once we know how to select samples wisely.

ASTROBIOLOGICAL PAPERS WARNING ON THE NEED FOR IN SITU SEARCHES FIRST [19659014] For astrobiologists who talk about the need for on-site searches, first see


The legal and practical problems are formidable and do not seem to have been addressed at all yet. Using the analysis of Margaret Race's legal status and published estimates of the time needed to build a Mars sampling reception facility to meet the required specifications, then if they started the legal process today, it is almost certain that they could not return the sample. before 2040.

It would not be an option to ignore the legal requirements, not today. At the time of Apollo, they could publish the provisions to protect the Earth on the day of the launch of Apollo 11, without giving anyone time to object or even study them. That would not be allowed today, and those old regulations were canceled long ago and generally accepted as symbolic and useful to show how those things can go wrong.

Today that direct access to the legal process would not be allowed. There is a great increase in awareness about environmental problems that we did not have in the 1960s and many treaties and national legal requirements that have been added since then.

Nor could it be done under COSPAR. It can be a sample return from a comet or meteorite, because they can show that there is no risk to the Earth's environment, since we obtain samples of such objects that enter our atmosphere all the time. But they can not use the same reasoning for a sample return from Mars. Previous studies examined this carefully, and the influx of Mars samples through meteorites is not equivalent to a sample return. In fact, it is not easy for life to reach ejections from the surface of Mars, or survive the trip to Earth. There are impacts on Mars every one or two million years capable of sending rocks to Earth, but most of them are found in the southern highlands, meteorites come from at least one meter below the surface, and most of them pass through. thousands of years in transit. and the largest meteorites are expected to be 60 cm in diameter before entering the Earth's atmosphere with the outer layers removed by ablation in the fireball of the reentry.

Therefore, it must be treated as potentially dangerous to the Earth's environment. The requirements for a sample return installation have increased with each revision. Originally in studies in the 1990s, it was a simple glove box in a level 4 biocontainment facility. These requirements became increasingly stringent as a result of discoveries of ultramicrobacteria, studies of the minimum possible size of extraterrestrial microbes (which are believed to be around 50 nanometers, a quarter of the minimum size for modern life on Earth) and the discovery of how easily capacities can be transferred through the lateral transfer of genes, if life is related, through GTA of the order of 10 nm upwards.

The most recent study of the European Space Foundation required a $ 500 million installation with design requirements never before met that has to prevent the escape of any particle 50 nanometers in diameter or more (a quarter of the resolution limit of 200 nm for a limited diffraction optical microscope). The latest ESF study left open the possibility that future studies may further increase the requirements.

What makes it so expensive and the approval process so complex is that we have to show that it can protect the Earth from any conceivable alien biochemistry, at a time when the only biochemistry we know is on Earth. We would build the same facility to receive an unsterilized sample of a habitat in the Proxima Centauri system!

The installation must also be operational and in use at least two years before the mission to collect the sample is launched from Earth. Preliminary studies warned that it may take between 7 and 10 years to get up and running, followed by an estimated 5-6 years to become familiar with the procedures

But the legal situation should also be resolved, before the mission could be launched. Nor is it likely that the facility will be built until the legal provisions are in force.

Margaret Race analyzed in detail the legal processes that would have to be completed before we can return a sample of Mars to Earth, even to a specially designed receiving facility.

Before a return sample, we have to achieve, in this order

  • Several years: Declaration of environmental environmental impact for the NEPA + laws on quarantine to be enacted, which implies a broad public consultation. The average time for an EIS in the twelve months ended September 30, 2016 was 46 months.
  • Several years: Presidential review of possible large-scale effects on the environment, after other national laws.
  • It can be done together with the other work: International treaties to negotiate and national laws of other countries

Margaret Race does not estimate a total time for all this. As a rough estimate, a decade seems optimistic to complete it.

  • 7 – 10 years: build the facility
  • 2 years: operational before launch (minimum requirement, most likely 5 to 6 years)
  • 2 – 4 years: to collect the sample and return it
    (If we follow the Mars 2020 plan, the tracking vehicle has to retrace at least part of the Mars 2020 route to retrieve the samples, in tubes that are dropped on the surface of Mars in small caches from time to time when).

That adds up to an extra 11 to 20 years after the legal process has been completed. Total from 21 to 30 years. The process of building and testing the installation could only take 20 years if we make the highest estimates there.

This means that if we want a sample to be returned to Earth by 2040, we should start this process immediately in 2018: there is no time to lose In fact, it is probably too late to reach a launch date of 2040. It would not be a great surprise if it were delayed until 2050 or later, either due to legal delays or delays in the construction of the facility and its start-up.

After two decades of passing all laws, approving the installation, building and testing it, our understanding of Mars through on-site searches could be developed to the point of demonstrating that the native life of Mars is harmless and discovering that the set The process was unnecessary.

However, it is also possible that during this time we will find life on Mars that would be dangerous to the Earth's environment. The reason why the installation would be legally required is because of this possibility.

The lessons learned from Apollo show that we must be very careful, if our back pollution measures are going to be more than a symbolic measure. We also have many examples that have shown to the general public and our elected officials that environmental protection matters.

If this is accepted, then it is correct that said procedure have detailed impact evaluations, and that the public participation is encouraged at each stage of the process. En cualquier caso, independientemente de lo que piense que son los derechos o errores de esta, es la situación en la que nos encontramos.

Para el análisis legal

Para la escala de tiempo para construir la instalación del estudio NRC

Para los detalles de el estudio más reciente de 2012 del ESF con los requisitos de 50 nm e idealmente de 10 nm

Entonces, ¿qué podemos hacer?

Creo que si esta misión realmente continúa, seguramente decidirán ya sea esterilizar las muestras o devuélvalos a otra ubicación, como GEO anterior.

Puede hacer esto a través de COSPAR sin necesidad de aprobar numerosas leyes o construir una instalación de devolución de muestras en la Tierra a un diseño nunca probado antes.

Seguramente cuando se enfrenta con el prospecto de gastar $ 500 millones adicionales por adelantado antes de poder lanzar la misión, aprobar numerosas leyes y no poder devolver la muestra hasta 2040 o 2050, tomarán la decisión de esterilizar cualquier material devuelto a la Tierra y devolverán un una década antes en th e 2030s.


Esto es para la situación en la que pensamos que la muestra podría contener vida pero que si lo hace, no sabemos lo suficiente sobre esta vida como para decir algo al respecto o sus capacidades.

En esta situación, creo que dado que no tenemos ninguna experiencia en el manejo de la biología extraterrestre, es mejor no devolver las muestras a la Tierra en absoluto. En cambio, ¿y si lo devolvemos a una instalación telerobótica encima de GEO? Elegí esta ubicación porque es la órbita más alejada en términos del delta v de la Tierra o la Luna de cualquier punto en el espacio cislunar.

Esto también tiene la gran ventaja de que está muy por fuera del alcance de cualquier residuo orbital de la Tierra de LEO o MEO (órbita media de la Tierra). Cualquier residuo de los propios satélites GEO será de movimiento lento, ya que son casi estacionarios entre sí. Entonces, cualquier colisión tendrá una velocidad relativa baja y no podrá enviar desechos a órbitas mucho más altas. También está lejos de la Tierra y de la Luna en términos de delta v, y es una órbita dinámicamente estable a largo plazo. Todo esto parecería ser el lugar más seguro para devolverlo. También es de fácil acceso desde la Tierra.

El obvio círculo exterior de puntos blancos en esta imagen muestra los satélites en GEO junto con los restos orbitales en la órbita del cementerio por encima de GEO. Tenga en cuenta que es estacionario en relación con la superficie de la Tierra, por lo que los satélites allí tienen un movimiento relativo muy bajo. Los satélites en GEO se retiran a esta "órbita del cementerio" 300 kilómetros más arriba al final de sus vidas. Para ver más imágenes, vea la galería de desechos orbitales aquí.

Sugiero que un buen lugar para regresar una muestra de Marte sería unos miles de kilómetros, tal vez diez mil kilómetros por encima de GEO. Bien lejos de GEO o la órbita del cementerio. Lo más lejos que puedes estar de la Luna o la Tierra en el espacio cislunar en términos de delta v.

Necesitas más de un kilómetro por segundo delta v para llegar a la Luna o a la Tierra desde allí. Sin embargo, es de fácil acceso desde la Tierra, lo que debería hacer que sea relativamente simple enviar equipos telerobóticos allí


Este video muestra el escombros orbitales en movimiento, y desde diferentes ángulos.

Al igual que con la idea anterior, podríamos devolver algunas muestras a la Tierra de inmediato, siempre y cuando las esterilicemos primero. Eso debería satisfacer a los geólogos. I suggest using ionizing radiation to sterilize these samples again, for the same reason as before, because that happens anyway on Mars, and would still preserve some evidence such as chirality and complex chemistry for astrobiologists too, if there was any life there before it was sterilized. It's also easy to take account of for the geologists, who already disentangle the ionizing radiation effects of the journey from Mars to Earth when studying Martian meteorites.

If the unsterilized samples are shown to be harmless quite quickly, we just return them as is (perhaps sterilizing them to be sure to start with), much as we did with the Moon rocks. This saves years of legislation (probably a decade or more to pass all the laws), and hundreds of millions of dollars of expense for designing, building and operating a facility that is never needed.

Returning to above GEO simplifies the whole process hugely.

  • No new legislation is needed to do that. It can be done within all the existing laws, as for sample returns from comets and asteroids. This eliminates the need for many years going through legal processes, and perhaps even into decades, just passing all the legislation to return it to Earth
  • You don't have any concern about the staff not using the right protocols because it is all operated from Earth. Nothing the staff can do, by mistake, laziness or attempts to cut corners can lead to life from the spacecraft above GEO escaping into the environment of Earth.
  • There is no risk of sample release to the environment of Earth as a result of natural disasters, human error, etc such as hurricanes, or earthquakes, lapses of protocol, design issues, or even terrorists, or the fiery heat of entering the Earth's atmosphere from orbit.
  • Saves half a billion dollars of up front cost – the Earth based sample receiving facility has to be built and up and running before the sample return mission is launched. This way, all the missions to study the sample above GEO can be treated as extended missions. That's equivalent to an entire new Discovery class mission. The mission to retrieve the sample to above GEO corresponds to a stage we might well do anyway, to retrieve the capsule before return to Earth to deal with the possibility of sample container breach in transit from Mars.
  • If the samples are rapidly shown to be of no great astrobiological interest – as most astrobiologists expect at present – you can just sterilize them and return them to Earth and don't need to do any other special handling, but treat them like the Mars meteorites. This is a huge cost saving. In this case you don't have to study it telerobotically in GEO, but just sterilize the whole thing and return it to Earth as in the previous suggestion.

It also has the great advantage that we design for what we discover as the mission progresses. There is no need to design an all purpose "swiss knife" of a faculty able to deal with all conceivable biochemistries. For instance if it is viable early life, based on RNA or even just primitive autopoetic cells, it might be easy to establish at an early stage that there is no possible hazard for Earth at all. In that case again, perhaps it doesn't need to be studied in a biohazard containment facility at all, but just protected to keep Earth life out of the sample. We don't need to establish that all life on Mars is safe for Earth, just that there is no hazardous life in the sample itself.

On the other hand, we might decide it needs extreme caution . For instance, we might do that if it is some exotic form of life which is not based on DNA at all, or if we decide that it is has a much more complex genome than any Earth microbe, billions of years advanced on us and we can't figure out what it does.

Also, this is a big plus when you consider the natural human inclination to ignore low probability risks of extreme events – if we do need precautions – the planners and staff will know it is potentially hazardous and will take great care. They would never do something the equivalent of opening a hatch because the astronauts might get seasick. They will design a protocol that really does work, and think through all eventualities, and take great care to make sure that it is going to work and be effective, and is not just a symbolic gesture.

In short, the three possibilities are:

  • If we find possible life and precautions are neededwe apply them based on knowledge, not trying to second guess any possible extraterrestrial biology. Everyone is highly motivated to take suitable precautions
  • If we find life that is so "feeble" that no precautions are neededthen there is no need to build what would then be a totally unnecessary facility and the legislation will surely be simpler and at any rate passed easily with no opposition.
  • If it has no great astrobiological interestwe sterilize the sample and return it to Earth.

So then the main remaining question is – is this idea to return a sample to above GEO itself safe against accidents? Is there any risk of any of the material in the sample getting to Earth?

So, first, the only thing that could damage and release the sample above GEO is an impact but there wouldn't be any risk from spacecraft debris, as any debris in GEO or the graveyard orbit a few hundred kilometers above GEO wouldn't travel far because of their low relative velocity. So the only real chance of an impact leading to release of the material from the sample, would be from natural debris from asteroids and comets. Assuming it has thrusters to position itself as a satellite, then it could also maneuver to avoid such hazards, just like the ISS, but it might be an issue detecting small debris at that distance from Earth and its radar systems. It would of course have Whipple shields to protect from micrometeorites.

So, is there any chance that a natural meteorite hitting a spacecraft above GEO, with Whipple shields, and able to "dodge debris", could send viable life to Earth from the satellite? I leave this for experts to look into in detail, if the idea seems to have merit.

Another question to look at is, is there any chance of a failure to retrieve the sample to above GEO. Well there, the approach would be similar to the Asteroid Redirect mission. So – the intermediate stage would be, perhaps, to return it to a Distant Retrograde Orbit. This is an orbit that is stable over time periods of centuries, and is within easy reach of GEO in terms of delta v. It's an orbit that is in synchrony with the Moon, so a 28 day orbit around Earth, but it is also highly elliptical. The satellite orbits Earth more slowly when further away than the Moon and faster when it is closer to Earth, and so as seen from the Moon it seems to orbit it in a retrograde fashion. It's a more stable orbit than a prograde orbit around the Moon and has the advantage that it can be as large as you like in diameter, even continue all the way to LEO in a retrograde orbit around the Moon. But it's also a prograde orbit around Earth so it's easy to get from it to GEO

As a 28 day orbit around Earth, DRO is also far more accessible to a spacecraft from Mars than LEO, assuming it doesn't do aerobraking in Earth's atmosphere, or return directly in a fast re-entry to Earth.

This calculation is for the opposite direction, from Earth to Mars, but it gives a good idea. The authors find that you need a delta v of 3.29 km / sec from DRO to LMO (Low Mars Orbit) compared to 5.758 from LEO to LMO. The delta v would be similar for a flight from LMO to Earth. The main drawback is that the delta v depends on the position of the Moon at the time of departure from Earth, so optimal trajectories repeat only once or twice a month.

This is actually similar to ideas in the literature to return the Mars sample to DRO around the Moon, and then for astronauts to retrieve it and return it to Earth. The only difference is that my suggestion here is to retrieve it robotically, rather than asking astronauts to retrieve it manually, and then return it to above GEO instead of to LEO.

See this suggestion by Lockheed Martin to use astronauts to retrieve a Mars sample from DRO using the Orion spaceship (once ready). Other proposals though assume a fast re-entry to Earth's atmosphere at 12 km / sec (see for instance page 49 of this report). It would have a higher delta v requirement than that of course.

See also my


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