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#460
by
Robotbeat
on 31 Mar, 2015 00:50
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Indeed.
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#461
by
the_other_Doug
on 31 Mar, 2015 01:43
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It also occurs to me that the unmanned ARM spacecraft could be designed to have its propellant tank refueled during the manned operations. How hard can transferring a few tens of pounds (or more) of xenon be in microgravity?
That would demonstrate even more useful technology for future exploration missions. It would also let you send the robotic spacecraft off again and again to different small bodies, pick off samples, and bring them back for additional sample collections by manned vehicles. And, if it proves that gravity tractor systems work and that it can deflect half-km-long bodies, we could even have the added plus of it becoming a readily deployable planetary defense device out there, just waiting for a chance to be used for real...
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#462
by
TrevorMonty
on 31 Mar, 2015 02:33
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Unfortunately NASA has an uphill battle when it comes to PR for this mission. Some opponents say it will not get us closer to moon or Mars.
The ISRU (especially for oxygen) potential, has not been pushed by NASA. The tonnes of oxygen in this boulder alone could help kick start moon missions. At around $10-20m(FH) a tonne to lunar orbit this boulder is worth over $100m in oxygen if it can be extracted commercially.
For Mars missions being able to extract oxygen for fuel from the moons would save billions.
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#463
by
jongoff
on 31 Mar, 2015 02:40
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Indeed.
There are several ways of reusing some or all of the hardware, and it is a very good idea, assuming the myopics don't kill ARM before it flies (or turn it into a pointless fly an SEP module to nowhere mission).
~Jon
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#464
by
jongoff
on 31 Mar, 2015 02:42
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It also occurs to me that the unmanned ARM spacecraft could be designed to have its propellant tank refueled during the manned operations. How hard can transferring a few tens of pounds (or more) of xenon be in microgravity?
That would demonstrate even more useful technology for future exploration missions. It would also let you send the robotic spacecraft off again and again to different small bodies, pick off samples, and bring them back for additional sample collections by manned vehicles. And, if it proves that gravity tractor systems work and that it can deflect half-km-long bodies, we could even have the added plus of it becoming a readily deployable planetary defense device out there, just waiting for a chance to be used for real...
Well, to refuel an SEP module, you're probably talking several thousand pounds of propellant (I don't recall the pmf of the NASA Asteroid Retrieval Vehicle, but I'd be surprised if it didn't hold at least 2-3 tonnes of xenon). That said, I like the idea and think it's totally possible.
~Jon
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#465
by
Robotbeat
on 31 Mar, 2015 03:11
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Unfortunately NASA has an uphill battle when it comes to PR for this mission. Some opponents say it will not get us closer to moon or Mars. ...
And flying to nowhere would?
I have not seen a single well-reasoned critique of ARM, just a lot of baseless name calling and one-true-solutionism.
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#466
by
Robotbeat
on 31 Mar, 2015 03:12
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I wrote this as a comment in The Space Review:
Why Asteroid Redirect is a good idea:
1) Planetary defense. With the selection of Option B, ARM is now a direct demo mission for deflection of asteroids large enough to pose substantial danger to Earth, i.e. asteroids larger than 140m in diameter. In fact, the currently targeted asteroid is 400m in diameter. This is big enough to obliterate a fairly large-sized country and cause massive regional destruction. By using the efficient local-mass-augmented gravity tractor method, ARM will demonstrate precise and measurable moving of the target asteroid. If this was all that ARM was supposed to do, it would be worth the $1.25 billion. This significantly enhances our species' odds of survival which should be good enough reason to do ARM with its modest cost. But, once you’ve demonstrated you can deflect a genuinely representative threat to the planet, why stop there?
2) Asteroid mining. ARM, especially Option B, is the first time that humanity is handling tons of asteroidal material in-space. The boulder, once deposited in lunar orbit, will serve as an excellent proving ground of asteroid mining techniques. Asteroid mining companies Planetary Resources and Deep Space Industries are currently small. They are not the multi-billion-dollar-a-year giants one imagines would be needed to mine asteroids. But at very least Planetary Resources IS capable of fielding smaller spacecraft. With the far shorter latencies to lunar orbit than the orders-of-magnitude farther heliocentric orbits of near Earth objects, asteroid mining start-ups will be able to quickly test out new mining techniques using telerobotics instead of the much more cumbersome high-latency-tolerant techniques that make Mars rovers 90% slower than the teleoperated Soviet lunar rovers. New spacecraft could arrive at the boulder in days instead of months and years for an object beyond Earth orbit entirely. While we’re still figuring out asteroid mining, this shorter control loop is critical to advancing the technology for a cost that makes it still worth it. Asteroid ISRU could fuel up our Mars spacecraft without requiring the expensive launch from Earth.
3) Lunar gateway. One proposal docks a small hab module to the ARM spacecraft, serving as a kind of miniature Mars transfer vehicle or as an embryonic lunar gateway station, where a reusable lunar lander may dock and refuel or where a Mars Transfer Vehicle may dock and refuel and be provisioned for another mission. Longer lunar orbital missions could be done than one could get away with using just a capsule, so very-low-latency immersive lunar telerobotics could be done to prepare a lunar base in addition to the other roles. This hab could be shielded against radiation. Which brings me to another point:
4) Early ISRU. Once the boulder is captured, it could be ground into gravel and used as radiation shielding. One boulder would be enough to block the vast majority of solar radiation, but with more, we could block even the majority of galactic cosmic rays:
5) The ARM spacecraft could, in principle, be used multiple times when refueled. This would allow the same craft to capture several boulders, allowing samples to be returned routinely from many different scientifically and/or industrially interesting asteroids. And once the spacecraft is developed and the overall concept tested and verified, more could be built (by, for instance, commercial ventures), and with greater capability.
6) Scientific sample return. NASA is spending $800 million on Osiris-Rex, a mission which may only return a handful of material from an asteroid. That’s only 33% less expensive for orders of magnitude less material. I personally know some scientists who do magic with micrograms of celestial material, but there are who different methods and techniques one can use to study samples when you have dozens of kilograms of samples. Additionally, the vehicle could possibly be refueled, so more samples could be taken at a later date. The scientific community is understandably suspicious of human spaceflight encroaching on their mission (fearing a loss of autonomy and resources), but if we’re going by scientific value for the buck, a strong case can be made that the $1.25 billion for a large boulder (with dozens of kilograms returned and possibility for more samplings and later, more boulders) is easily worth it if $800 million is worth it for a single sampling of dramatically less material. This is another example of one of the benefits that would justify the expensive even if it stood alone.
7) Half the development challenge of ARM will be developing a large-scale solar-electric propulsion system and testing it in-orbit. This is a critical enabling step for lower-cost Mars missions but also would enhance lunar base logistics and direct-to-asteroid missions. Additionally, having such a powerful solar-electric platform would enable powerful robotic missions and could serve as a high-performance upper stage for sending probes to outer planets missions.
8 ) And now we get to the most well-known aspect: as an intermediate step on the way to Mars. But make no mistake: Orion and SLS were previously planning on simply launching into empty space on their first crewed flight. This is still essentially a test flight. This is not a dedicated mission, this is much more an Apollo 8 or Apollo 10, or perhaps more like a Gemini or an Apollo 7 but with the benefit of returning scientifically and industrially interesting samples. Skeptics of ARM say it’d be much better if NASA would send people to a beyond-Earth asteroid or to the Moon or to Mars. Wonderful idea! Except you STILL need a crewed test flight first. You’re not going to launch to an asteroid 4 months away on the first crewed flight of Orion, are you? Skeptics are blinded to the fact that the alternative to ARM isn’t some splendid Moon or Mars mission, but instead a shakedown mission to an empty point in space, maybe a couple of selfies, and then back to Earth. The shakedown cruise needs to happen anyway, the $1.25 billion ARM mission makes it far, far more than just a test mission to empty space. (And if SLS/Orion were canceled because Elon Musk or XCOR or whoever somehow makes space travel super cheap in 10 years, then no problem, we can send up a Dragon!)
The real issue the skeptics have is it’s not THEIR favorite solution or destination. One-true-solutionism infests the space community. You see it in the comments here, too. A lot of space enthusiasts have some single idea that they think would automatically make everything better, and so we should stop doing everything and focus on that one true solution--nevermind that one person’s “one true solution” is another person’s boondoggle. Oddly, you never heard one peep out of them denouncing the $800 million Osiris-Rex mission, did you? But ARM is not “one true solution,” instead it’s a confluence of 3 or 4 different needs that happen to coincide so the same spacecraft can accomplish all of them for a modest price comparable to a mission like Osiris-Rex. It’s not a re-orienting of the human space program (and in fact could be used to pluck a boulder from Phobos/Deimos), it’s simply a remarkably good idea which has only gotten better with the latest announcement of Option B.
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#467
by
KelvinZero
on 31 Mar, 2015 04:08
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One thing I would add is that this piddly mission could be enough to finally have our foot in the door of space settlement. The problem with ISS, SLS and even flexible path is that we have to swallow a lot of hyperbole claiming that what we are doing now is a necessary step to what we actually want to do.
It may not be romantic, but you don't actually need anything beyond this, just repeat, repeat, repeat. And government loves repeats because that means money to established lobbies.
Just keep doing this and we would end up practicing everything relevant to asteroid settlement. Keep collecting multiton asteroid samples with SEP. Keep visiting high earth orbit, keep practicing ISRU and developing confidence in long duration missions in your DSH. Keep leaving infrastructure because it is cheaper than bringing it home.
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#468
by
jongoff
on 31 Mar, 2015 04:37
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Unfortunately NASA has an uphill battle when it comes to PR for this mission. Some opponents say it will not get us closer to moon or Mars. ...
And flying to nowhere would?
I have not seen a single well-reasoned critique of ARM, just a lot of baseless name calling and one-true-solutionism.
Well, I haven't seen a well-reasoned takedown of ARM. I have seen some good suggestions for how to improve ARM that the suggesters thought were a takedown.
For instance, I agree with the MIT professor that we should be putting more resources into asteroid detection, which would improve our odds of making ARM better.
And I agree with a few others that finding a way to bring back more than one sample would also be cool--whether via refueling/reclawing the ARM vehicle after it delivers its first boulder, or via a multi-claw/multi-lander ARM vehicle with a multi-asteroid grand tour trajectory (a crazy concept I've been meaning to mention in a blog post that hasn't happened yet due to lack of time), or some other variation on the theme.
But yeah, I'm underwhelmed with the "I'm an MIT professor and I can't figure out how this relates to putting people on Mars" arguments, especially when the answer seems pretty obvious.
~Jon
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#469
by
TrevorMonty
on 31 Mar, 2015 13:19
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This mission has one plus, no on going costs. Once boulder is delivered to stable lunar orbit there shouldn't be any ongoing costs.
Any moon missions will result in on going costs, especially if it involves cislunar gateway and reusable lander.
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#470
by
notsorandom
on 31 Mar, 2015 14:51
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Here is another devil's advocate type question. What is the utility of demonstrating ISRU at an asteroid when in the process of doing so SEP is proven as a viable way to move large masses around? The main point of ISRU is to provide propellant but a reusable SEP tug can do everything from Earth to Mars better than chemical and nuclear thermal. To get from the surface of Mars to Mars orbit propellant can be created more easily from the Martian atmosphere. The extraction of resources for life support seems of little value as advances in closed loop life support will reduce the total amount needed for the mission.
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#471
by
Robotbeat
on 31 Mar, 2015 15:07
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Certain types of electric propulsion can use ISRU-derived propellants. Besides, you still want to have shielding, consumables, and material to manufacture stuff in space. And for high-thrust, you still need chemical propulsion
SEP makes ISRU more feasible, not less.
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#472
by
notsorandom
on 31 Mar, 2015 17:00
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Certain types of electric propulsion can use ISRU-derived propellants. Besides, you still want to have shielding, consumables, and material to manufacture stuff in space. And for high-thrust, you still need chemical propulsion
SEP makes ISRU more feasible, not less.
For Mars missions it is unlikely that there will be such a need to do in space manufacturing that ISRU becomes an enabling function. This specific SEP uses xenon and not much of it. Only a few tonnes are needed versus several hundred for chemical. The propellant for SEP is such a comparatively low amount that is is easy to bring from Earth. By the end of the decade we will have 2 maybe even 4 LVs (if you count NGLV and BFR/MTC) which can fling large payloads to L2 where they can use SEP to complete the trip to Mars. On the Mars end the high thrust chemical parts can be done easier using IRSU from the planet's atmosphere.
One of the key problems of ARM is its justification by saying it will enable Mars missions. The price of the mission can be applied to other things which will be much more useful such as demonstrating ISRU on the surface of Mars. The SEP tug could be demonstrated by lifting payloads to L2 from LEO enabling cheaper rockets to lift heavy mission elements.
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#473
by
Darkseraph
on 31 Mar, 2015 17:13
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Shielded Cycler slowly propelled into its orbit by electric propulsion using two smaller reusable vehicles on both planets to ferry crews back and forth using chemical propulsion+ISRU. That is where I would imagine they're actually very complimentary and Zubrin's objection to things like Vasimr falls apart. It doesn't even need those massive nuclear engines that are supposedly impossible.
Also, things that are not living and don't have to be sent as fast as humans can be nicely sent one way with electric propulsion. For the amount of cargo a base or colony might need, this could be a pretty smart way to go.
Technology like this has the capability to scale missions that require something the size of Saturn V down to something merely the size of a Falcon Heavy that can be repeated over and over.
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#474
by
Robotbeat
on 31 Mar, 2015 20:01
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Certain types of electric propulsion can use ISRU-derived propellants. Besides, you still want to have shielding, consumables, and material to manufacture stuff in space. And for high-thrust, you still need chemical propulsion
SEP makes ISRU more feasible, not less.
For Mars missions it is unlikely that there will be such a need to do in space manufacturing that ISRU becomes an enabling function. This specific SEP uses xenon and not much of it. Only a few tonnes are needed versus several hundred for chemical. The propellant for SEP is such a comparatively low amount that is is easy to bring from Earth. By the end of the decade we will have 2 maybe even 4 LVs (if you count NGLV and BFR/MTC) which can fling large payloads to L2 where they can use SEP to complete the trip to Mars. On the Mars end the high thrust chemical parts can be done easier using IRSU from the planet's atmosphere.
One of the key problems of ARM is its justification by saying it will enable Mars missions. The price of the mission can be applied to other things which will be much more useful such as demonstrating ISRU on the surface of Mars. The SEP tug could be demonstrated by lifting payloads to L2 from LEO enabling cheaper rockets to lift heavy mission elements.
It demonstrates SEP at large scale, something clearly needed. There is no "problem" with the fact that the mission is doing other things as well, that is in fact a huge strength. The biggest expense is likely the large SEP component.
It would be a lie to say this DOESNT contribute to advancing Mars exploration. But that isn't the only thing it does.
Why do people have such a hard time grasping the concept of a mission which is useful for more than one thing? This absolutely boggles my mind.
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#475
by
Endeavour_01
on 31 Mar, 2015 20:19
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I am definitely not a fan of ARM (at least the human part of it). ARM was
dreamed up endorsed by the policy wonks in the White House in order to keep the Presidents promise of a "journey" to an asteroid by 2025 without giving NASA the proper resources to go. I would much prefer a dedicated lunar gateway for a lunar return and further exploration to Mars.
That all said I agree completely with Robotbeat about trying to avoid one-true solutionism. NASA is doing a good job with what they are being given and they are trying to do ARM in a way that will enable further exploration. The robotic part can pay dividends in terms of SEP, sample return, and planetary defense. The manned portion (if handled properly) can, like Robotbeat said, be used as the foundation for a lunar gateway station.
My preference is for a mission much different than ARM but I am not married to a particular architecture. It may not be the mission I want but if ARM happens I can promise you I will be glued to my TV and as excited as a kid at Christmas.
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#476
by
Rocket Science
on 31 Mar, 2015 20:41
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If this mission is going to be done I would rather see a partnership with NASA and commercial space. Let the agency redirect the asteroid and then let a commercial entity explore and mine it for resources. Keep NASA focused on new technology for a Mars mission...
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#477
by
notsorandom
on 31 Mar, 2015 21:01
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It comes down to space policy. The law states that the goal of NASA human spaceflight is to get to Mars. ARM has to be passed by the same folks who passed that law. ARM will use the money for getting to Mars so it should further that goal. That it does other things is good, but if those other things aren't useful for Mars and cost more to do then they will get a pretty skeptical look. There is very limited funding for a Mars mission so every dollar deserves to be spent to gain the most capability for a Mars mission.
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#478
by
GWH
on 31 Mar, 2015 23:16
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I like the general idea of the ARM mission, and I can see why they are going after option B.
Personally I just wish it could be a little more ambitious. I posted earlier questioning wondering how much more it would cost to simply produce two retrieval craft. Sdsds answered using the Spirit/Opportunity rovers as an example, stating that the development of the rovers accounted for the bulk of the cost. While both these rovers have been incredibly successful - Spirit did become stuck after all while Opportunity could carry on for years after (no doubt learning lessons on the design and traction limits). The margin of safety provided through redundancy here has returned significant amount of science.
While it is all simply wishful thinking, if NASA were to go after two targets with two probes they would not only double the asteroid science but also mitigate risks of failure. Instead of doing a one off to grab a piece of a single asteroid turn this into something more substantial - a more thorough beginning to a catalog of samples of NEO asteroids and leaving a whole lot more in lunar orbit for later interests to investigate. Of course if one really wants to dream you could imagine them writing off some of the risk of using one of those low cost reused rockets looming on the horizon...
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#479
by
Robotbeat
on 31 Mar, 2015 23:26
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I am definitely not a fan of ARM (at least the human part of it). ARM was dreamed up by the policy wonks in the White House in order to keep the Presidents promise of a "journey" to an asteroid by 2025 without giving NASA the proper resources to go. ...
So basically, you don't like ARM because "Obama."
If you're complaining about lack of resources, you should be complaining to Congress, holding NASA under threat of sequestration. Congress holds the purse strings, and they've generally been actually giving NASA less money than the President requests.
edit:Also, you'll have to tell the scientists and engineers at the Keck Institute in California that they're secretly policy wonks for Obama.
