Since it would seem from a recent hearing that –in the Capitol and Capital a least– there is a strong negative feeling towards the Asteroid Redirect Mission [ARM <wiki>]: it behoves its supporters to come to its aid. Bearing in mind that, with it’s cancellation, the technological development of an advanced ion engine (and all the rest of it) …is likely to be abandoned as well. Thus: yet another nail in the coffin labelled “Flexible Path <wiki>” as outlined by that august body the Augustine Committee <wiki> (Source materials).
Ahem. My little contribution under the section “Plan For Exploration Beyond LEO Responses” (pdf, 56k)
Whilst ARM and the Asteroid Redirect Crewed Mission (ARCM) is a far cry from President Obama’s original proposed human crewed asteroid mission it is probably for the good.. Baby steps rather than giant leaps being the order of the day in our modern, risk averse, culture. I for one was immensely pleased at the new direction for NASA. For all the polar hype the moon is a dry hole when it comes to water . The real watering hole, I suspect, will be Ceres. (As will be noted in previous articles on this blog: this author is of the firm belief that the asteroids represent the paramount materials source for the evolution of humanity into a Kardashev II civilization. <wiki>. Since any extra-planetary society will be some 60% water –by mass alone– it is thus necessary to: FOLLOW THE WATER!
(But try not to crawl back down into another planetary cradle whilst doing so. Please!)
At this point I must admit that the boulder retrieval option selected by the review committee was a grave disappointment. Even if, as the most recent publication suggests [FAST 23rd November 2015 pdf 4.3MB], the mission is lucky enough to discover and recover a lump of water rich carbonaceous chondrite. (Handy to the sun blasted surface!) The likelihood is that its geology will so closely match that of any such similar meteorite that serious questions will be subsequently raised as to the value of the mission. This was not true of the other proposal: the recovery of a sizeable 10 metre diameter cosmic dust bunny. The morphology and composition of which would have been radically different from anything that survives a ballistic style plummet to the ground. Indeed the exploration and characterization of such a friable body would also have provided a real challenge to any EVA carried out from Orion: tethering, sampling, dust mitigation, utilization, bootprinting, flagplanting,… All would have been a deal more complex than a rendezvous with a small hard rock!
Moreover a small hard rock with a diameter in the region of one to five metres has a high probability of lacking the surface properties suitable for taking a bootprint and any flag planting in a small hard rock is more likely to raise a derisory smile rather than a national wave of pride or a global gasp of amazement!
However all is not lost.
I would suggest in the strongest possible terms that –if a boulder is to be retrieved– then ARM now be focussed on a boulder retrieval from the surface of Phobos or Deimos, after a ~600 day loiter in Mars orbit characterizing the surfaces of the two bodies in question and, ideally recovering a boulder from a shadowed crater or, better still, determining if a boulder represents material blasted off from the Martian surface and subsequently impacting one of the two moons.
In the latter case one would truly be able to claim that NASA was carrying out Martian surface studies in Lunar Orbit!
Failing that serendipitous outcome a Phobos or Deimos sample return would be seen as a real step in “The Journey to Mars.”
One that Congress would be less likely to axe.
One could take this opportunity to wax lyrically on the advantages of a Phobiean or Deimosian base camp: utilizing the abundance of local materials for: radiation protection, fuel, building materials,… 3D printing of household utensils; as well as developing the necessary tools, skills and techniques for interactions with the boundless riches of Near Earth and Main Belt objects to be found in the inner system. One could spend several pages explaining just why developing a permanent settlement in Mars Orbit is that much more easy –Certainly more easy than laboriously building one on the Martian surface, only to find that the really interesting spot is fifty kilometres beyond the range of any Mars Buggy!– and the huge advantages of carrying out surface explorations using robotic avatars and real time teleoperations. At a stroke removing the huge costs of long term surface life support; providing the flexibility to explore anywhere on –or under– the Martian surface with no risk to human life and, last but not least, meeting with the prime consideration of planetary protection.
This astrobiologist would quite happily defer human landings on Mars until after the day that we have conclusively determined that Mars was indeed lifeless but, thanks to terraforming, is now a suitable place for colonization!
However ARM does not stop there.
I would seriously suggest that ARM be developed as a modular carrier. In its FIRST mission: the boulder grappling mechanism is its payload. After the Orion mission ARCM#1 is over then a second Orion mission Asteroid Redirect Maintenance Mission [ARMM] be scheduled to refurbish and refuel ARM; now relabeled: Asteroidal Rendezvous Surveyor and Explorer [ARSAE. Phew! :-P] parked at L1. A third Orion mission –or possibly a robotic space tug– would subsequently dock the payload for the SECOND ARSAE mission. Here I would suggest an “all hands” request by NASA for Phobos Landers. NASA would select the best six and then ARSAE would deliver them to the surface. The various teams would then conduct various experiments: mobility; ISRU; exploration; surveying; digging; tunnelling;… utilizing ARSAE as a communications relay. After another ~600 day loiter in Mars orbit, a second set of small sample and artefactual returns would then accompany ARSAE on its return to L1. A THIRD MISSION would repeat the process only with Deimos as the target. In between each ARSAE mission there would be one or more Orion missions: servicing; repairing; upgrading ARSAE in much the same way that NASA maintained Hubble. The synergistic combination of human flexibility and robotic durability producing results much greater than the sum of its parts. As part and parcel of these Orion missions: L1 could be developed as a “Lunar Gateway” complex as envisaged by various prior studies. OASIS springs to mind.
Note that the ISS –or any subsequent LEO station– is NOT the ideal location for such refurbishment. Better to have the solar electric arrays in the harsh cis-lunar environment rather than continually ploughing a track through the Van Allen radiation Belts.
Also Note that with ARSAE in Mars orbit it can at least provide stunning views of the Martian surface as well as contribute to the Martian orbital satellite collective. In this way one of the major problems of ARM is mitigated: a long period of time when NOTHING IS HAPPENING!
When ARSAE as a concept has been proved, then further –more powerful– iterations of an ion powered modular carrier can then visit asteroids in keeping with the original plan.  Now delivering ever bigger rocks to a growing settlement at L1. If nothing else IRSUed into a radiation shelter.
With enough rocks in situ we can then start building the Bernal sphere!
 Let’s take Paul Spudis’s values at 600,000,000 tonnes at North pole, say it’s all ice (Not a given..) and that ice and water are equivalent density [1 tonne ice = one cubic metre.]
= 1.2 km^3 for two poles worth (Not a given.) A little over a Gigatonne! Sounds a lot doesn’t it?
To put this in a terrestrial context. (Involving sailing!)
Lake Superior: (Now that is a lot of water!) 12,000 km^3 Whoops too big! Perhaps a little smaller and human made:
Lake Mead: 32 km^3 (Currently running out of water…) Getting closer but still too big. O.K. let’s look for something smaller.
Loch Ness: Scotland 7.4 km^3 Smaller still
(and so on…) until
Lake Windermere 0.98 km^3 (being generous) the largest natural fresh water lake in England.
Windermere pop. 8,245 although the lake obviously supports other villages. That’s it!
The total water to be had on the Moon is rougly equivalent to a small lake in England.
Find a reservoir near you with that sort of capacity (~1 cubic kilometer) and that is the size of population it will support.
Doesn’t seen so “abundant now does it?
Then consider the robotic infrastructure required to extract a mixture of: cyanogen; ammonia; acetylene; complex organics and all the other cometary ices *that are not water* from stratified deposits spread over thousands of cubic kilometers of rugged terrain… That is BTW in permanent shade and as close to absolute zero as not to make any difference.
Add humans and the costs skyrocket!
Even with perfect recycling and perfect life support systems and perfect seals …and a policy of making sure that any transients lose weight during their Lunar Vacation; any “Lunar Authority” allowing this precious hydrogen to be exported as fuel or in the form of foodstuffs deserves to be lined up against the wall and blasted with an ice mining laser.
Ceres (0.51 km/s to orbit), on the other hand, may contain more fresh water than the whole Earth.
wiki:fact “contains 200 million cubic kilometers of water, which is more than the amount of fresh water on the Earth. ”
Moon (2.38 km/s to orbit). One cubic kilometer…
Now do you see why asteroids are so attractive?
This author would strongly protest this constant mantra emerging from certain parties in the United States that there is abundant water for (commercial) exploitation at the lunar poles.
Moreover any water we do find, should be carefully conserved. Firstly as a scientific resource to be studied and then, secondly, utilised on an international basis in keeping with the spirit of the Treaty on Outer Space. And, yes, the Moon Treaty too! That Lunar Lake Windermere is clearly the common heritage of Humanity until we start importing water from other locations to grow our lunar community.
 This rockrat would seriously suggest 2010 TK7. And sod the deltaVee! After all this is a lump of rock some 300 odd metres across! A bit of tunnelling and bingo O’Neill Station is in situ.. Later a bubbleworld ( Dandridge and Cole) could be contemplated. Pending this happy day I would also suggest that NASA urgently and seriously consider a Gravity Tractor experiment –or other asteroidal deflection technique– with the aim of reducing and stabilizing the orbit of TK7 –over decades if need be– until its lissajous has been domesticated to a level that permits a human visit! It’s three hundred metres across!!!
BOTE assuming that its pure water (!) that’s 14,137,167 tonnes of cis-lunar/ Lagrangean space station!
In the right place!