Mars 2020 will drill and store several surface samples until a return-to-Earth vehicle arrives. The rover will then use its arm to move its sample box to onboard the return vehicle.

Could the rover in the same way physically transfer a digital memory unit for return to Earth?

If the radio-to-Earth bottleneck is bypassed by an interplanetary "sneakernet", then the instruments could, in the end, return much more data to Earth. MSL Curiosity seems to return about 250 megabyte per day. Not much compared to (radiation hardened!) physical memory, right?

  • $\begingroup$ The word "sample" is there for a reason. We want samples to microtome and process, not megabytes of relatively useless lower-resolution sensor data. $\endgroup$ – Deer Hunter Dec 10 '14 at 21:39
  • $\begingroup$ I actually don't think that the bottleneck is a problem that needs solving. At least, not with an interplanetary sneaker-net. Part of the reason is that sure, 250 MB/day might not seem like a ton, but time is cheap; over a three-year period, you could stream back about 250 GB of data without adding any weight or cost to the mission. And each successive mission to Mars has had more bandwidth - so maybe Mars 2020's orbiter could handle 500 MB/day (granted, it takes more power given the same receivers on Earth). Patience is a virtue after all ;-) $\endgroup$ – Kirkaiya Dec 10 '14 at 22:46
  • $\begingroup$ @Kirkaiya But instrument sensitivity and data return is increasing quickly. Astronomers talk about Big Data as if it was Big Bang. And a kilogram of digital data in a sample return might be cheaper than a com sat at Mars, or a huge radio antenna in the DSN on Earth. $\endgroup$ – LocalFluff Dec 10 '14 at 22:59
  • $\begingroup$ @LocalFluff Astronomers have massive amounts of data coming from the many telescopes (both optical and radio) around the planet. It's hard to imagine anything on that scale coming from a Mars rover, unless you were transmitting HD video (not very useful, and so unlikely to happen). I'm not saying your idea won't ever happen, but it doesn't seem (to me) like a pressing issue for the next few missions to Mars. I believe given the long timelines on these missions, time is very cheap compared to lofting cargo to/from Mars, and so the cheaper and slower answer is the better one. $\endgroup$ – Kirkaiya Dec 10 '14 at 23:03
  • $\begingroup$ @Kirkaiya Or maybe they today choose low-data instruments because of the limit set by radio communication. $\endgroup$ – LocalFluff Dec 11 '14 at 0:36

The latency is killer, though -- 8 months to several years before mission controllers can analyze and respond to data they find. Curiosity's controllers are looking at the pictures it's sending, deciding which terrain features are interesting, and directing it to investigate, iteratively.

A somewhat smarter autonomous rover with a rack of removable SSDs could probably take a lot of pictures and movies for later sneakernetting, without restricting its material sample payload too painfully, but I suspect the non-visual instruments are providing more interesting data, and at a low enough data rate that transmission isn't a bottleneck.

  • $\begingroup$ Radio could be used as today, for operations and very select science data. With a memory capsule, returned together with the rock samples, ALL collected science data could come home. $\endgroup$ – LocalFluff Dec 10 '14 at 22:30

It's been over forty years since the last sample was returned from the Moon. Yet to this very day, Earth-bound scientists are managing to extract meaningful data from those returned samples. Those returned samples were and still are a treasure trove of information. This is what makes a sample return from Mars the holy grail of Mars exploration, much so than terabytes of data from a rover that is inherently limited in power, size, and analytic capabilities.

The devices we humans send to Mars are extremely limited in capability. There's only so much sense a scientist can make out of remotely sensed data sent from a limited device (e.g., a Mars rover). It's a bit of a matter of garbage in, garbage out.

Bringing back samples from Mars would be a game-changing event. This would enable scientists who are stuck on the surface of the Earth to have decades to make sense of those returned samples. As I mentioned above, scientists are still managing to garner information from the samples returned from the Moon. The same would apply to samples returned from Mars, in spades. (Soooory, I just couldn't resist the pun.)


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