A fairly big probe, with a combined chemical/ion propulsion. Most of it's chemical impulse would be for Mars orbit insertion in the vicinity of Phobos. Spacecraft fires penetrators into Phobos for combination analysis and anchoring. Then, the probe descends to Phobos surface by reeling in the penetrator's cables, scoops up some regolith. then using SEP, thrusts out to Deimos to repeat the process - the samples are cached in a re-entry capsule. Then, chemical & SEP thrust back to Earth where the capsule enters the atmosphere for touchdown in the Australian outback.Variations? The probe could perhaps rendezvous with a couple sample return craft fired up from the Martian surface and it could cache their samples, too.
Would like to see something that could extract significant drill core samples say down 100 meters, break it up into segments and send that back, from Mars surface as well in a few locations, but that may have to wait until the experts and labs get there. Still I think it would be easier for that deep a sample to be drilled from Phobos and Deimos, chopped up and not mixed up to be loaded into a return vehicle robotically than doing the same thing on the surface of Mars (and realistically to give us signficant understanding, in lots of different locations on Mars).
[...]As for Philae, I don't think that the harpoons ever fired.
Well, Philiae has shown that if you don't know the hardness of the underlying strata, firing hooks is a risky experiment on whether or not you can actually get an anchor.
Since interplanetary drilling seems to be so challenging, what about instead using directed explosives, like armor piercing weapons? No moving parts. Couldn't that dig up materials from quite some depth? Hayabusa 2 will blow up subsurface samples to be collected and returned to Earth. Sure, a drill could give better science, but now to begin with, wouldn't explosives be a good alternative?Animation:http://jda.jaxa.jp/result_strm.php?lang=e&id=2e032c23f72832dba634998602294f69
Quote from: TakeOff on 03/13/2015 11:41 AMSince interplanetary drilling seems to be so challenging, what about instead using directed explosives, like armor piercing weapons? No moving parts. Couldn't that dig up materials from quite some depth? Hayabusa 2 will blow up subsurface samples to be collected and returned to Earth. Sure, a drill could give better science, but now to begin with, wouldn't explosives be a good alternative?Animation:http://jda.jaxa.jp/result_strm.php?lang=e&id=2e032c23f72832dba634998602294f69No. They would make it more complex because:A. The act of firing them at the target would put a large reactive force on the spacecraft necessitating larger thrusters and suchB. If the projectile is self propelled, the complexity is self evident.c. The reaction to the explosives is unquantifiable and thus it is unknown how to protect the spacecraft thus adding complexity. Even after the explosion, some debris would remain in the area, even orbiting the targetd. the explosives would contaminate any samples
Well, then why not do what Deep Impact/Hayabusa 2 will/did do? Non-explosive excavation, with a projectile made of a substance that wouldn't be found on the target body (copper, for instances). It should also be simpler to make the impactor itself a spacecraft, but that will drive up cost and might increase mission complexity...
Maybe an explosives driven "harpoon core sampler" (yes, I'm making this up) could even capture a nice intact unpolluted core sample? I'd be surprised if not huge research and development has been and is being spent on controlled explosives in the budgets for weapons, mining and construction industries. The second problem with drilling is the mechanics. Explosive bolts on the other hand are very reliable. Many successful spacecrafts have used lots of them.
What would a crewed landing on Phobos or Deimos be like? Considering the very low surface gravity, is it enough to have an Orion hoover very near above it and let out astronaut geologists on an EVA to collect well selected stuff? Or could an Orion even be landed, using some relatively simple and low weight surface interface module attached to the service module? Of course the transfer habitation and many many other things are missing for a human mission to Phobos or Deimos, I realize that. I wonder if at least the cost of developing and bringing along a specialized lander could be saved on such a mission. If a crewed Earth launch and reentry vehicle like Orion could work also as a temporary vehicle for EVA's on Phobos and Deimos (having the mothership waiting in the background). EDL and ascent is one of the big headaches for sending humans to Mars. This is one of the potential big advantages of going to its moons instead. But how much easier is it really? Is a particular Phobos lander spacecraft required?
So much can be done at those fascinating little worlds in partnership with telerobotics and sample return probes.
Quote from: MATTBLAK on 03/13/2015 08:55 PMSo much can be done at those fascinating little worlds in partnership with telerobotics and sample return probes. There's really no good evidence that this is true. I don't know of any studies that have looked carefully at the value of telerobotics.