Bringing Mars back to Earth

Apr 20, 2012 By Nola Taylor Redd
A Mars sample return mission would require three parts: a sample-collecting rover, a lander with a fetch rover to jet the rocks into space, and an orbiter to relay communications and bring the samples home. Credit: E2E-iSAG/S. McLennan et al

The search for life should be an essential component of a sample return mission from Mars, according to a recent report examining the science behind such a venture.

A team of scientists, including technical advisors from NASA and the , and scientists from the United States, Canada, and Europe, identified and prioritized four scientific objectives involved with bringing material from the red planet back to Earth. The search for life, past and present, topped the list, while the preparation for came near the bottom of the list.

"The decadal survey and others have pretty much concluded that the next logical step is sample return," said Scott McLennan, of Stony Brook University in New York.

McLennan, who was part of the international team, was confident that a mission exploring the top four concerns listed in the report could be planned given the information known about Mars.

"There're good reasons to believe we can identify a place where we would get back the samples that would address the high-priority questions."

The search for science

After examining previous scientific objectives, and incorporating recent perspectives from the Mars science community, the international team proposed four aims to a future sample return mission, with the hopes of providing a guide for future campaigns.

The search for ranked at the top of the list. While looking for on Mars would be akin to searching for a needle in a haystack, the team felt that current research could help target areas likely to have been hospitable to life in the past.

"Most people think that the conditions under which life might have initially evolved would be different from the conditions on the present day surface of Mars," McLennan said.

"Mars right now would be a pretty tough place to live."

While most of Mars resembles a dry, dusty wasteland, scientists think the surface of the planet once boasted , considered the best ingredient for the formation of life. As on Earth, such life could have existed in a wide variety of environments.

"If we can find the kinds of rocks that reflect those environments - and we think we can, with some confidence - then that strikes us as the place to look."

But make no mistake - though searching for life on Mars today might be a challenge, all samples returned would be examined for evidence of its existence.

Next on the list of objectives is an increase in knowledge about the martian surface. Knowing where water may have flowed should clarify past habitability, while examining the surface also could reveal the climate changes that cost Mars its atmosphere.

Landing on Mars this summer, the rover Curiosity, part of the Mars Science Laboratory mission, will carry a mini-laboratory that will allow it to examine the red planet in detail. Credit: NASA/JPL-Caltech

The third objective is to better understand how the planet has evolved over time. By studying both old and young volcanic rocks, scientists hope to obtain a better understanding of the geologic history of Mars. Similarly, these rocks could provide clues about how the Martian magnetic field has changed over time. As part of understanding how the has changed, the team also hopes to gather a sample of its atmosphere, enabling them to better understand how it has diminished over time.

Preparing for a manned mission to Mars falls near the end of the list. Still, bringing home pieces of the planet could help scientists locate potential resources on Mars that could be used to return astronauts to Earth, as well as identify possible hazards that explorers might encounter while interacting with the top layer of the planet.

A magnified view of the meteorite from Mars, ALH84001. Ejected into space, it landed in Antarctica 13,000 years ago and was collected by scientists in 1984. The orange and black disk patterns are made of carbonate. The debate still rages over whether or not the meteorite contains evidence of microscopic Martian bacteria fossils. Credit: Kathie Thomas-Keprta and Simon Clemett/ESCG at NASA Johnson Space Center

"Before we have a manned mission to Mars, we need to have a sample return," said Janice Bishop, a planetary scientist who studies Mars at the SETI Institute.

Along with a better understanding of the planet, she points out that such a mission also would provide a test run for going to Mars and coming back to Earth, something that the current one-way missions to Mars just don't do.

"To send a mission that's returning to Earth is much harder," she said.

Three launches, one mission

To complete a sample return mission, the group concluded that at least three trips to Mars would be required.

The first would launch a sample-collecting rover. The team recommended the rover be capable of collecting at least 30 rocks. Ideally the rover would gather samples from a number of different Martian environments, some with duplicates to provide better context. Weighing in at about 15 grams each, the samples would be large enough to answer a variety of questions,.

The team also stressed the importance of being able to switch out samples if a better opportunity came along. Being able to select the best choices from a bag of rocks that were already collected should eliminate that concern.

"For Mars, we probably won't have the luxury of multiple sample return missions as on the Moon," Bishop said.

"Which samples you actually grab to bring back is essential."

The second launch would put an orbiter around Mars, which would provide the necessary communications for the arrival of the third mission, a lander with a "fetch rover" that would pick up the samples the first rover had collected, the samples themselves lasting indefinitely. The orbiter would then be responsible for bringing the samples back to Earth.

The team stressed that the missions need not take place back to back; the first, sample collecting rover could explore Mars for many years before a pickup was arranged. Thus a commitment to one mission did not necessarily require an immediate commitment to all three.

A closer look

Over the past fifteen years, has sent three orbiters, a lander and three rovers to Mars, and has worked with ESA on another orbiter. Mars Science Laboratory (MSL), with its rover, Curiosity, is set to reach the planet this summer.

"The ability to do remote work has gotten better and better, and in some ways, it's just staggering," McLennan said.

MSL, for instance, "is going to take samples, grind them up, and put them into a real, honest-to-goodness analytical lab that we would be happy with on Earth."

Yet there are some things that we simply cannot do on the surface of Mars, either because the necessary instruments can't be transported, or because the samples require impossible manipulations.

In Mars missions, discoveries often lead to new, unanticipated questions. For remote analysis, you're simply stuck with the instruments that you’d sent to Mars. However, samples of that are brought back to Earth can be studied in ways not originally considered in the mission planning.

"When you bring a sample back, you can continually re-ask questions," McLennan said.

Both McLennan and Bishop stress the benefits of international co-operation. The most obvious is sharing the cost.

"Most countries are having a difficult time funding large missions on their own," Bishop said.

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User comments : 13

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TopCat22
3 / 5 (2) Apr 20, 2012
the new ion powered engines should make this unmanned venture considerably cheaper than going to the moon, landing and returning.
Lurker2358
2 / 5 (3) Apr 20, 2012
capable of collecting at least 30 rocks. Ideally the rover would gather samples from a number of different Martian environments, some with duplicates to provide better context. Weighing in at about 15 grams each


BS.

you actually expect to find "fossils" lying around in some random rocks on the surface of a planet with 300mph dust storms and 200 degree differences in winter and summer temperatures?

Any surface fossils would have been destroyed eons ago due to wind and heat/frost wedging, you fools.

If you really want to have a chance in hell of finding anything, you need meter(s) deep core samples from multiple sites, preferably the bottoms of canyons and non-meteor basins(i.e. something that had the potential to be a lake BEFORE it was obliterated by a meteor).

You're not going to find microbial fossils in the bottom of a meteor crater that was vaporized and melted on impact, nor in the middle of a wind-blown wasteland. All you'll find is melt-rock or sand respectively.
Lurker2358
2 / 5 (4) Apr 20, 2012
And just for the sake of argument, what if you DO find some sort of microbial life?

How are you going to put it in a container, and sterilize the outside of the container, to be sure any life that might still be in it is not active to contaminate the Earth whenever the Earth lander returns the sample?

It's highly unlikely they'll find anything more advanced than some stray amino acids or a prion anyway, but what the hell? I wouldn't want that freed in the environment on Earth.

The outside of the retrieval units, both the lander and the orbiter, will need to be decontaminated and sterilized again before Earth re-entry. This would likely required a FOURTH stage of the mission, involving a manned intercept mission in Earth orbit to sterilize the outside of the vessels and take them aboard an air-tight landing vessel...

Costs start adding up fast.
GSwift7
2.3 / 5 (3) Apr 20, 2012
the new ion powered engines should make this unmanned venture considerably cheaper than going to the moon, landing and returning.


Not really. Besides being closer, the moon has low gravity and no atmosphere. Mars presents a unique combination of engineering hurdles. It has a lot more gravity than the moon, so you'll be falling relatively fast on entry. However there's a thin atmosphere. That makes it a strangely difficult place for landing a large spacecraft. If the atmosphere were thicker, like earth, then you can use air friction and parachutes to slow down, but the atmosphere is too thin for that alone. Or, if there was less atmosphere (or none at all), then you can just use thrusters to slow down, but mars has just enough atmosphere to make thrusters work poorly. The MSL is using a combination of a prototype heat shield braking system, parachutes, braking thrusters, and a sky crane. Any heavy lander will require something like that. Very expensive to do all that.
GSwift7
2.3 / 5 (3) Apr 20, 2012
The outside of the retrieval units, both the lander and the orbiter, will need to be decontaminated and sterilized again before Earth re-entry


They worked that out when we did the moon missions. The lander doesn't come back to Earth, and the orbiter doesn't land on Mars.

Take a deep breath, and calm down. It's going to be okay.
GSwift7
3 / 5 (4) Apr 20, 2012
with 300mph dust storms


Almost irrelevant with such a thin atmosphere. Mars has very little weathering. Something going 300 mph with almost zero mass still has almost zero momentum.

and 200 degree differences in winter and summer temperatures?

Any surface fossils would have been destroyed eons ago due to wind and heat/frost wedging, you fools


Again, almost irrelevant with almost zero moisture in the air. Frozen CO2 doesn't expand like water does, and water that goes straight from solid to vapor doesn't cause freezing expansion. You need liquid to solid transition to cause expansion and crack rocks. The inside of a small sedimentary rock would be preserved excellently.

Also, pieces thrown out of a meteor crater should still have microbe fossiles in them, if any were there in the first place.
Russkiycremepuff
1 / 5 (1) Apr 20, 2012

If you really want to have a chance in hell of finding anything, you need meter(s) deep core samples from multiple sites, preferably the bottoms of canyons and non-meteor basins(i.e. something that had the potential to be a lake BEFORE it was obliterated by a meteor).
- Lurker

It is also of major importance as to the time of year and latitude for which the sample return mission's future for landing the crafts. The optimum latitudes should be far enough from the poles and within the martian late spring/early summer to avoid any chance of cold weather or terrible heat. If there are microbes at all, they would most likely be in under the surface regolith and within rocks. Anyplace that affords some measure of safety from the elements should be examined for microbial life.
This mission could be done more cheaply if accomplished by the NASA and the ESA/Russian space program combined. This would be a strictly science venture and nothing political, since all countries will benefit
Torbjorn_Larsson_OM
3.7 / 5 (3) Apr 20, 2012
Seems to complex. But the idea of stretching the expenses might just work.

TopCat22, good idea. GSwift7, I assume ion engines are proposed to be used for cheap transfers as the current Dawn mission. The sample return can take years as opposed to manned missions, space will keep the samples relatively pristine.

@ Lurker2358:

You don't seem to know about paleontology and astrobiology (or chemistry - amino acids and (hah!) prions as pathological respectively natural contaminants), and hence look like the fool. Trace fossils such as carbon isotope ratios can be found in the remaining CO2 atmosphere already.

Weathering doesn't destroy organisms embedded in sediments, but are the actual mechanism that paleontologists rely on to bring out the fossils to the surface in the first place.

The Gale crater, which MSL is going to visit, is such a place. And there are others for the sample & return to target. Did you really think this team would make simple mistakes?
Torbjorn_Larsson_OM
3.7 / 5 (3) Apr 20, 2012
@ Lurker2358:

As for your sterilization routines, you seem confused considering that you believe not even fossils will be found. The risk of cross contamination is minute, since evolution adapts organisms to their environment. Mars organisms wouldn't make it on this inhabited planet, and vice versa.

But for many reasons, from social over political to science, chemical and biological cleanliness will be minimized. But the suggested procedures are much less contrived, because of cost naturally but also because of feasibility, there is a need to keep the samples from harm.
Lurker2358
1 / 5 (1) Apr 20, 2012
The outside of the retrieval units, both the lander and the orbiter, will need to be decontaminated and sterilized again before Earth re-entry


They worked that out when we did the moon missions. The lander doesn't come back to Earth, and the orbiter doesn't land on Mars.

Take a deep breath, and calm down. It's going to be okay.


Not really. The LEM reconnected with the capsule, so um, and hte astronauts walked around in open space on the surface of the moon, and brought the suits back inside.

In the case of the Moon, I believe they probably just assumed it was void of life after the first few orbiter missions, based on temperatures and radiation.

There no evidence that I know of that any decontamination was done at all. They even said the moon dust got in the LEMs and stuff and was all over everything.
verkle
1 / 5 (1) Apr 21, 2012
What are the mathematical chances that life randomly formed both on earth and on Mars? After doing this calculation first, then consider whether it is worth the hundreds of billions of dollars for such a mission, and that the search for life should be an essential component such.
GSwift7
1 / 5 (1) Apr 23, 2012
The optimum latitudes should be far enough from the poles and within the martian late spring/early summer to avoid any chance of cold weather or terrible heat


terrible heat? on mars?

from wiki:

Surface temperatures have been estimated from the Viking Orbiter Infrared Thermal Mapper data; this gives extremes from a warmest of 27 °C (81 °F) to 143 °C (225 °F) at the winter polar caps. Actual temperature measurements from the Viking landers range from 17.2 °C (1.0 °F) to 107 °C (161 °F)


I would guess that it is more important to avoid the spring and summer dust storms, since mars temperatures shouldn't be a problem for any robotic probe. We make probes that operate just fine under much more severe temperature conditions than those found on mars. Dust storms could cause far more trouble than temp ranges.
tbonefrog
not rated yet Jun 12, 2012
We seem to want to relive 20th century space exploration, when we have an opportunity to became a true space civilization instead:
- do the science on mars with robotic laboratories, i know they are not quite there yet but they will be soon
- build as much of the space mission as possible on the moon, and launch ion drive missions from there by rail gun, maybe figure out a reverse rail gun for landing on the moon. transfer the bare minimum to earth from the moon
- i don't know the orders of magnitude but if the muon flux is large enough to support muon fusion in space, that would be way cool
- dittos to looking deep in valleys/caves for martian life, what atmosphere mars has is thicker in the surface depressions several km below average altitude, and in deep caves you might find liquid water and hence life, also less radiation and diurnal variation

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