How Genesis Crash Impacts Mars Sample Return

[kai_25]

NASA’s Genesis sample capsule not only stirred up dust and dirt when it crash landed in Utah last week, but also debate concerning the return to Earth of future extraterrestrial samples – specifically from Mars. <br /><br />While the high-speed impact of the return canister was not planned, the capsule’s design did permit the survival of some samples. However, due to a breach of the science canister caused by the crash, the space specimens were contaminated once exposed to Earth’s atmosphere.<br /><br />The Genesis probe, along with the homeward bound Stardust spacecraft carrying bits of a comet and interstellar particles, serve as precursor missions to snag, bag, and lug back to Earth select pieces of Martian real estate. <br /><br />NASA engineers and scientists have been grappling for decades with methods, procedures, and the price tag for robotically returning Mars samples. <br /><br />One concern is that Martian samples could contain microbial life. Whether that’s the case or not, great care in handling specimens of Mars is a high priority -- not only to protect our planet from virulent biology, albeit a low probability, but also guarding the samples from Earth contamination.<br /><br />The desert dust kicked up by the Genesis is settled as scientists work to retrieve some of its precious cargo. But talk about how best to orchestrate a future Mars sample mission is far from coming to rest.<br /><br />Trashed and twisted hardware<br /><br />The Genesis sample canister augured into the Utah Test and Training Range (UTTR) at a speed of nearly 200 miles per hour (322 kilometers per hour). Onboard was a treasured stash of solar wind samples, embedded in breakable collector arrays.<br /><br />With the capsule successfully rocketing through Earth’s atmosphere, the plan then called for a mid-air helicopter recovery of the sample return capsule underneath an unfurled parafoil – a wing-like parachute. <br /><br />But the parachute system failed to deploy. The return sample canister was ba

 

[centsworth_II]

I was very impressed by how well the Genesis capsule faired in its hard landing despite <b>not at all</b> being designed for one. It's not hard to imagine a few changes to the aerodynamic design of the capsule that would greatly reduce the speed of impact, and some shock absorbing features to protect the contents, making a free-fall, secure landing certain. Nothing to fail, right? Well, there is one worry. What if the heat shield fails to separate, thus failing to expose the aerodynamic features of the capsule? <div class="Discussion_UserSignature"> </div>

 

[JonClarke]

Lithobraking rather than aerobraking is the wave of the future. <img src="/images/icons/laugh.gif" /> With respect to the heatshield, presumably it would not separate. Since people are so paranoid about sample return, the KISS principle is the way to go.<br /><br />Cheers<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[acid_frost]

What if they somehow allowed a return sample to be placed in orbit and then retrieved by the Stations crew and then brought home on whatever return vehicle we have? That seems to be logical in some way.<br /><br />Or have some type of landing ballons as they had for the Rover to land on Earth?<br /><br />Just some random thoughts.<br /><br />Frost

 

[yruc]

<blockquote><font class="small">In reply to:</font><hr /><p> <font color="orange"> What if they somehow allowed a return sample to be placed in orbit and then retrieved by the Stations crew and then brought home on whatever return vehicle we have? That seems to be logical in some way. </font><p><hr /></p></p></blockquote><br /><br />While logical, the cost and logistics for it are impractical. You would have to increase the size of return craft to the size of a school bus or so to hold enough propellant to slow down enough to enter orbit. Then launch a vehicle to retrieve it and bring it back to earth if not using the ISS.<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p> <font color="orange"> Or have some type of landing balloons as they had for the Rover to land on Earth? </font><p><hr /></p></p></blockquote><br /><br />While sound in principal, not 100 % sure it would work on earth as the main reason it works on mars is due to the fact mass has significantly less gravity than earth. It might work on earth, though you would still have to have the parachute system like the rovers, and airbag inflation system. Which again would add mass to the return sample. <br /><br />The easiest and cheapest way would probably just design the craft to survive a free fall crash into the ground. Though this would add some mass for strengthening the return craft.

 

[spacester]

3.34 km/sec deltaV returning Aug 7 2007 from a Hohmann transfer from Mars<br />With Isp = 375 sec (LOX & Kerosene engines)<br />mo / mf = e ^ ( g*Isp / deltaV) = 3.007 = 3.0 <br />mo = mf + mp<br />mp/mf = 3.0 - 1.0 = 2.0<br />mp / mf = mass of propellant / mass of spaceship and payload.<br /><br />So a sample return craft could rendezvous with ISS by having fuel and oxidizer tanks holding twice as much mass as the rest of the craft, including the samples.<br /><br />50 kg samples (110 pounds)<br />400 kg spaceship (880 pounds)<br />900 kg propellants = 1984 pounds<br />SSET weighs 16 million pounds full<br />Less 58,500 pounds empty<br />16000000 - 58500 = 15941500 pounds of propellants<br />Assuming the same ratio for our Mars return vehicle,<br />1984 / 15941500 = 1.24455E-4<br />can apply to the empty weight of 58500<br />1.24455E-4 * 58500 = 7.28 pounds empty weight of return craft's tanks.<br /><br />Kerosene tanks are not the same as LH2 (edit) tanks, but still . . . that seems low, doesn’t it?<br /><br />Well I usually use the figure 0.95 for the percentage of mass of a full cryogenic tank that is the mass of the contents. Let's use 0.92 for a kerosene / LOX system's tanks.<br /><br />(1.00 - 0.92) * 1984 pounds = 158.7 pounds<br /><br />The mass of the tanks to contain enough propellant to return 880 pounds of spacecraft and 110 pounds of samples from Mars to Earth orbit is around 150 pounds. That leaves us with 730 pounds for our rocket engines and all the rest of the systems needed, that's a lot! More sample mass, then! Thicker tank walls, lots of redundancy. <br /><br />This craft would be placed into Mars orbit by a previous stage which would be refilled (from an on-orbit depot) while gathering samples and then perform the burn to go back to Earth. All you ask of it is to insert you into Earth orbit, just one solid burn. Come to think of it, a solid motor would work if the ISS crew has the capability (CEV) <div class="Discussion_UserSignature"> </div>

 

[JonClarke]

Hi spacester<br /><br />As I see it the issue is not whether it can be done, but whether it is worth doing. Given the paranoia about Mars sample return (there is an international organisation out there already campaigning against it) any sample return mission will have to demonstrate that it can maintain integrity in the even of a high dV entry and a hard landing. Given it has to withstand that anyway, any additional frills simply detracts from payload. As it is most current MSR designs return less than 1 kg (!!!!!!!) of sample you would not want to eat into that.<br /><br />Cheers<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[flynn]

*Update*<br /><br />Story from NewScientist<br /><br /><b>Genesis scientists analysing simulated samples </b><br /> <br /> <br />13:25 12 October 04 <br /> <br />NewScientist.com news service <br /> <br />Researchers are forging ahead with salvaging the most important scientific results from NASA's crashed Genesis space capsule. Fresh tests on how best to analyse the highly prized solar wind ions will begin this week, say mission leaders.<br /><br />The capsule, which crashed in Utah on 8 September, had spent 27 months in space collecting charged particles blown from the Sun's outermost layer. That layer is thought to reflect the composition of the gas-and-dust cloud from which the solar system formed about 4.5 billion years ago.<br /><br />Scientists hope this primordial composition would reveal how different planets and meteorites evolved such a wide range of isotopes of key elements such as oxygen and nitrogen.<br /><br />But that task was made much more difficult when the capsule slammed to Earth after its parachutes failed to open. Dirt from Utah's salt flats entered the ruptured science canister and most of the wafers on the mission's five collector arrays shattered.<br /><br />"Still, we're hoping we will get a fair amount of our top science priorities," says team member Roger Wiens, a physicist at Los Alamos National Laboratory in New Mexico. He says wafer fragments as small as a couple of millimetres across - of which there are thousands - can yield useful data.<br /><br /><b>Careful calibration </b><br /><br />And the most crucial instrument, which collected oxygen, survived nearly unscathed, with just one of four wedge-shaped concentrator targets broken. The instrument must be calibrated very carefully - a process that could take 18 months. "We're going to take our time to make sure it's done right," Wiens told New Scientist.<br /><br />A kidney-shaped sheet of gold foil also fared well. Sandwiched between other collectors that "crumpled like the front end of a car", the foil <div class="Discussion_UserSignature"> <font color="#800080">"All God does is watch us and kill us when we get boring. We must never, ever be boring" - <strong>Chuck Palahniuk</strong>.</font> </div>