I seriously don't understand the reasoning behind the ARM mission concept; why move the tiny asteroid to lunar orbit, just to send a crew to grab a few samples? If sampling it is the goal, surely it'd be far simpler and more cost-effective to take the samples roboticlly and return then to earth or LEO. (I'd bet you could get larger samples doing it that way). As it stands, the proposed ARM seems to me to be little more than a make-work mission for SLS/Orion, because with Orion's 21 day endurance, you can't actually send a crew to a NEO in situ (even assuming SLS/Orion had the needed Delta/V). The only possibly-useful aspect of the mission that I see is the SEP system needed for the retrieval probe, but that'd still be needed if the destination is changed from Lunar orbit to LEO (the original JPL study of asteroid retrieval assumed LEO/ISS as the destination, so it's not that far-fetched to think LEO is a viable destination to consider).
Quote from: CJ on 12/22/2014 12:47 amI seriously don't understand the reasoning behind the ARM mission concept; why move the tiny asteroid to lunar orbit, just to send a crew to grab a few samples? If sampling it is the goal, surely it'd be far simpler and more cost-effective to take the samples roboticlly and return then to earth or LEO. (I'd bet you could get larger samples doing it that way). As it stands, the proposed ARM seems to me to be little more than a make-work mission for SLS/Orion, because with Orion's 21 day endurance, you can't actually send a crew to a NEO in situ (even assuming SLS/Orion had the needed Delta/V). The only possibly-useful aspect of the mission that I see is the SEP system needed for the retrieval probe, but that'd still be needed if the destination is changed from Lunar orbit to LEO (the original JPL study of asteroid retrieval assumed LEO/ISS as the destination, so it's not that far-fetched to think LEO is a viable destination to consider). I was totally subscribed to your incredulous POV until I read/listened to some of the literature. The thing is - you're 100% right, you're not being hyperbolic. This is basically acknowledged by the proponents of the ARM mission at this point, when they say things like 'this is going through the ops program instead of the science program' during the last telecon. SLS/Orion needs something to do, something to train a generation of engineers in BLEO manned operations, something that would not put astronauts at risk on a 3-year mission, something that fit within NASA's existing budgetary outlook.This was the first thing they came up with. It really is that simple. Any science that gets done is an afterthought to this training mission. The technology developed, like a monster SEP system, will not be particularly difficult, but under the patronage of the SLS/Orion initiative with the intention of an actual mission, there will be somebody to pay for it to be integrated into an actual spacecraft. We've had ion thrusters and we've been developing lightweight solar panels for years, but without a mission, the tech dev budgets will pay for nothing that actually flies to space, so what's the point of implementing them in megawatt-scale designs?I have graduated from puzzled frustration to educated depression. It's pathetic groping through the constraints of program funding conditions that prohibit actual ambition.
Quote from: CJ on 12/22/2014 12:47 amI seriously don't understand the reasoning behind the ARM mission concept; why move the tiny asteroid to lunar orbit, just to send a crew to grab a few samples? If sampling it is the goal, surely it'd be far simpler and more cost-effective to take the samples roboticlly and return then to earth or LEO. (I'd bet you could get larger samples doing it that way). As it stands, the proposed ARM seems to me to be little more than a make-work mission for SLS/Orion, because with Orion's 21 day endurance, you can't actually send a crew to a NEO in situ (even assuming SLS/Orion had the needed Delta/V). The only possibly-useful aspect of the mission that I see is the SEP system needed for the retrieval probe, but that'd still be needed if the destination is changed from Lunar orbit to LEO (the original JPL study of asteroid retrieval assumed LEO/ISS as the destination, so it's not that far-fetched to think LEO is a viable destination to consider). I was totally subscribed to your incredulous POV until I read/listened to some of the literature. The thing is - you're 100% right, you're not being hyperbolic. This is basically acknowledged by the proponents of the ARM mission at this point, when they say things like 'this is going through the ops program instead of the science program' during the last telecon. SLS/Orion needs something to do, something to train a generation of engineers in BLEO manned operations, something that would not put astronauts at risk on a 3-year mission, something that fit within NASA's existing budgetary outlook.
It certainly could be a quite valuable mission.I'd much prefer a trip to an asteroid in its normal orbit, though. ARM sort of strikes me as an excuse to delay long-duration BEO human spaceflight, and I'm not convinced that developing a hab would be more expensive than developing the unmanned asteroid-catcher craft. (Especially since you could modify a Bigelow one rather than design something really new.)
Why not do an asteroid redirect mission then? As in, redirect the asteroid into a more agreeable synodic period? If your goal is to restructure the solar system to the benefit of humankind, get on with it.
{snip}5- I can't remember where I saw it publicly, but apparently one of the potential uses for the commercial-derived Hab module that NASA's studying under the NextSTEP BAA was to provide a hab module at the ARM asteroid sample to enable longer-duration exploration and study of the asteroid sample, and to demonstrate long-duration habitation at some place close enough you could safely make it home if something goes wrong. This would basically create a tiny man-tended NEO-lab in lunar orbit (that could also serve as a lunar gateway).I just think that so many of the naysayers have such a limited view of what's going on. Admittedly NASA hasn't provided a ton of clarity on exactly what they're trying to do, probably since they're trading two so very different options, but I hope that will continue to change in the 1st quarter of this new year.~Jon
At this stage of the game, a visit to an asteroid in heliocentric orbit would be a purely flags and footprints publicity stunt.
...4- I'm of the opinion that Phobos and Deimos have the potential of being key enablers for future Mars missions (via ISRU propellants delivered to LMO). The same hardware designed for Option B could be used to return a sample from those Moons....~Jon
We were designing for a 3.75m diameter boulder (about 90mT assuming 3.3tonne/m^3 rock) for our "Option B" ARM BAA design point. Now, I don't know if the rest of the system can handle that size with realistic destination asteroids, etc., but 1.5-2.5m is a lot smaller than what we've been focused on. Heck, the 1G ground test prototype we're building is sized for a 1m diameter boulder... ~Jon
Synodic periods - good point. I wasn't really thinking in terms of ISRU, at least for the first mission, but in terms of exploring the asteroid itself. Follow up missions wouldn't necessarily be to the same asteroid.If ISRU is the point, then yes, moving the asteroid makes sense.
5- I can't remember where I saw it publicly, but apparently one of the potential uses for the commercial-derived Hab module that NASA's studying under the NextSTEP BAA was to provide a hab module at the ARM asteroid sample to enable longer-duration exploration and study of the asteroid sample, and to demonstrate long-duration habitation at some place close enough you could safely make it home if something goes wrong. This would basically create a tiny man-tended NEO-lab in lunar orbit (that could also serve as a lunar gateway).I just think that so many of the naysayers have such a limited view of what's going on. Admittedly NASA hasn't provided a ton of clarity on exactly what they're trying to do, probably since they're trading two so very different options, but I hope that will continue to change in the 1st quarter of this new year.~Jon
If a couple modules were added, I could imagine somebody teleoperating a rover from lunar orbit. There was a paper or two about running rovers on the lunar farside from an orbiting Orion, I believe it was, so the idea's at least been investigated a little.
Quote from: jgoldader on 12/29/2014 09:19 pm If a couple modules were added, I could imagine somebody teleoperating a rover from lunar orbit. There was a paper or two about running rovers on the lunar farside from an orbiting Orion, I believe it was, so the idea's at least been investigated a little. The entire Lunokhod team is still scratching their heads about this one.
A quickly-moving, dextrous one commanded with less than a half-second time lag would be a major advance. ..