Top 10 Reasons Why Something ARM-like Is Worth Doing

[Up-front Disclaimer: My space startup is being paid under the Asteroid Redirect Mission BAA to do a study contract on one possible way to do the Option B mission. Even though we’re not dependent on follow-on work, I figured it was worth stating up front my potential biases.]

I’m not sure I’ve ever seen a major NASA program as nearly-universally disliked as the Asteroid Redirect Mission. Some people hate it for ad hominem reasons like the fact that the Obama Administration has been pushing it, or the supposition that Darth Garver (as they see her) came up with the idea. I’ve also heard a few anti-SLS/Orion people refer to it as a “pathetic attempt to reengineer the Solar System to make it handicapped-accessible for SLS and Orion”, or to come up with something for SLS and Orion to do that is more inspiring for them than endless Apollo-8 rehashes (but without the subsequent Apollo missions to follow). Ironically, I think some of the pro-SLS/Orion fanboys on the internet who hate it are afraid that ARM doesn’t really need SLS or Orion (which is true to some extent–in a NASA where Human Spaceflight was done more with PI-led, competitively selected, not-overly-politically-driven missions, I bet few PI’s would be suggesting SLS or Orion for this mission). Some of the Small Bodies scientists seem to hate it because they see it coming from the human spaceflight side, and think the whole thing could be done better without humans involved, and it wasn’t invented there anyway. All told, lots of people find lots of reasons to hate this mission.

But I wanted to provide 10 reasons why a mission like ARM might be actually be worthwhile:

  1. Adding a new, even more accessible moon to the Earth-Moon System: A lot of people fixate on the fact that we’re going to spend all of this money for a couple of astronauts to go out to a rock in lunar orbit, climb over it for a few days, and bring some samples back. What they conveniently ignore is that >99.5% of the material brought back will still be there, orbiting the moon for the next several hundred to several thousand years, in a fashion that is easily revisitable for a long time (docking adapter pre-attached, and at least for a while still attitude stabilized). And this new moon would be about as hard to get to as L1/L2. Which means that yes, future missions to it using a lightly modified CC vehicle are totally possible.
  2. Providing an ideal testbed for Asteroid ISRU development: Many people, including many of my friends, see the asteroids as the premier source of vast quantities of off-world resources. But while there are no shortage of low-TRL concepts for how to extract resources from asteroids, actually testing those out isn’t going to be easy. I think testing will be much easier when you have the ability to send people and robots, when you’re close enough that teleoperation of robotics is an option, and when you have frequent repeat visit opportunities where you can try new approaches, and where you can do your testing in a microgravity or near microgravity environment, like you would have at an asteroid.  I’m sure prospective asteroid miners like DSI or Planetary Resources wouldn’t complain about having one or more easy-to-access testbeds to work with.
  3. Providing a much larger sample quantity to work with than other existing or proposed missions: While scientists may be happy spending $800M to return 60g of material from an asteroid (OSIRIS-REx), and can likely tease out all sorts of information from that two Tablespoons worth of material, ISRU development needs a lot more material to work with. Even the smallest of Option B concepts I’ve seen brings back tens of tonnes of material, both rocky and regolith, which should be plenty to work with for ISRU development.
  4. Providing a good way of testing out a man-tended deep space habitat: As was reported by Jeff Foust at SpaceNews, one of the ideas NASA is looking at incorporating into ARM is attaching a prototype deep space habitat (possibly commercially derived if the NextSTEP BAA leads somewhere useful). This would allow visits of up to 60 day duration by crews of up to 4. While there are other ways you could test something like this (such as L1/L2 gateways), testing it in an operational environment would be useful. As would demonstrating the ability to do long-term habitation in close proximity to an asteroid.
  5. Demonstrating large-scale Solar Electric Propulsion (SEP) systems: This is one of NASA’s main interests in the ARM mission–in the land of expensive launch vehicles, very high Isp propulsion like you can get with SEPs can make many missions a lot more affordable. Even with low-cost earth-to-orbit transportation, SEPs probably make sense for a wide range of missions. Demonstrating the ability to use large-scale SEPs for tugging huge objects in heliocentric space, and performing precision injection maneuvers, etc. might be very useful. We already have a fair deal of experience with small SEP systems, but doing these sort of missions with 100kW+ class SEP systems can be pretty useful.
  6. Demonstrating Planetary Defense Techniques: If something like “Option B” (the grab a boulder option) is selected, NASA is interested in demonstrating the Enhanced Gravity Tractor method for deflecting the parent asteroid (see slides 27-29 of this presentation on Option B). Learning how to deflect potentially hazardous asteroids is probably one of the more worthwhile things NASA could be spending money on right now, and providing a way of getting real hands-on experience applying those techniques would be very useful. We have lots of theory on how this would work, but getting experience with a real, lumpy, non-idealized asteroid of significant (>100m) size would be really useful. And contra some of their critics, using a “Rube Goldberg arcade claw” to pick up a boulder and increase your spacecraft mass by 5-10x is a great way of allowing you to get measurable results in a reasonable amount of time.
  7. Developing Technologies for a Phobos/Deimos Large Sample Return: One of the keys to affordable exploration and settlement of Mars will be determining if Phobos and/or Deimos have water in them, and if so, figuring out how to extract it efficiently. Having a large source of propellant feedstocks available in Mars orbit (for supersonic retropropulsion on landing, hydrogen feedstock for surface ISRU, and earth-return propellant) could significantly reduce the amount of propellant needed for both round-trip and one-way Mars missions. If Option B is selected, and if it designed properly, it would be possible to use the same hardware (with slightly modified CONOPS) to capture and return a decent sized (>1 tonne) sample to lunar DRO for evaluation and hopefully ISRU process development/debugging. A manned Phobos and/or Deimos mission is something I strongly support in the future, but if they had enough info that they could be setting up a propellant extraction facility while they’re there (that we’ve already pilot-tested in cislunar space so we know it has a high probability of working), that would just be awesome.
  8. Providing the Beginnings of a Lunar Gateway?: It turns out that getting to and from Lunar DRO, and getting to/from the lunar surface from a Lunar DRO aren’t massively different from getting to/from Earth-Moon L1 or L2. The orbital dynamics is a bit more complex, but the propellant and travel times are relatively similar. And some lunar DROs can be long-term (centuries or millennia) stable without active stationkeeping. While if we were ready for going straight to the Moon (I’m actually a bit of a Moon-Firster believe-it-or-not), L1 or L2 might be slightly preferable to a lunar DRO as a location for a lunar gateway, if we did something like ARM, with the habitat module, you’d already have a de-facto start to a lunar gateway. One that will likely be setup (by NASA or follow-on efforts) with ISRU hardware, which would likely include at least rudimentary LOX/LH2 and/or LOX/Methane storage and handling capabilities (after all, if they’re going for a carbonaceous chondrite sample, extracting water will be a key part of what they’d be trying to prove). While this wouldn’t likely provide anywhere near enough fuel storage for a Constellation-class mission, it might provide enough propellant to refuel a “Golden Spike” class lander. And even if the asteroid itself only yields a mission or two or three worth of propellant, the tanks and handling equipment would be there and it could make shift as a miniature depot for earth-launched and eventually lunar-derived propellants. Lots of details have to be done right to make this feasible, but it’s possible that ARM could be done in a way that make future lunar missions easier.
  9. Providing More Experience with On-Asteroid Operations: If the Rosetta/Philae mission should tell us anything, it’s that there’s still a ton to learn, from an engineering standpoint, about how to operate successfully on the surface of large, low-gravity objects like asteroids or comets. While we’ll continue to get some small-scale experience using other robotic missions, and while a manned mission to a free-range asteroid will also provide a good way to get more data, ARM will likely extend our knowledge about how to do operations like these safely with large objects, and would likely provide good data increasing the likelihood of success of future manned missions to free-range asteroids.
  10. Leaving Something Permanent: One of the saddest things about the Apollo missions is that they didn’t leave anything permanent that made future missions any easier. When they were canceled all that was left was museum pieces, pictures, and a few hundred kg of rocks. But the nice thing about ARM is that once the asteroid sample has returned to lunar DRO, it’s there. It doesn’t require continued expenditures from NASA for it to stay there. Until we’ve mined every last kg of it, it’s going to be there orbiting the moon, close enough that almost any spacefaring country or business in the world can reach if it wants to. It doesn’t need an ongoing standing army that can be defunded. It doesn’t need a mission control to watch over it 24×7. It doesn’t need some sustaining engineering contract that’s going to suck up significant portions of NASA’s limited human spaceflight budget on an ongoing basis. It’s just there. Ok, if there’s a hab there or a more sophisticated node, it could require ongoing mission support when being used. But if for some reason they decided to stop visiting that node for a while, it would still be there, waiting to be restarted whenever someone cares again, or ready to be handed off to private companies or international partners once NASA is done with it. At least for a few centuries. Having something that accessible and that permanent out there is worth something, at least to me.
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Jonathan Goff

Jonathan Goff

President/CEO at Altius Space Machines
Jonathan Goff is a space technologist, inventor, and serial space entrepreneur who created the Selenian Boondocks blog. Jon was a co-founder of Masten Space Systems, and the founder and CEO of Altius Space Machines, a space robotics startup that he sold to Voyager Space in 2019. Jonathan is currently the Product Strategy Lead for the space station startup Gravitics. His family includes his wife, Tiffany, and five boys: Jarom (deceased), Jonathan, James, Peter, and Andrew. Jon has a BS in Manufacturing Engineering (1999) and an MS in Mechanical Engineering (2007) from Brigham Young University, and served an LDS proselytizing mission in Olongapo, Philippines from 2000-2002.
Jonathan Goff

About Jonathan Goff

Jonathan Goff is a space technologist, inventor, and serial space entrepreneur who created the Selenian Boondocks blog. Jon was a co-founder of Masten Space Systems, and the founder and CEO of Altius Space Machines, a space robotics startup that he sold to Voyager Space in 2019. Jonathan is currently the Product Strategy Lead for the space station startup Gravitics. His family includes his wife, Tiffany, and five boys: Jarom (deceased), Jonathan, James, Peter, and Andrew. Jon has a BS in Manufacturing Engineering (1999) and an MS in Mechanical Engineering (2007) from Brigham Young University, and served an LDS proselytizing mission in Olongapo, Philippines from 2000-2002.
This entry was posted in Commercial Crew, International Space Collaboration, ISRU, Lunar Exploration and Development, NASA, NEOs, Space Development, Space Exploration. Bookmark the permalink.

25 Responses to Top 10 Reasons Why Something ARM-like Is Worth Doing

  1. In the long run, transporting meteoroids to EML4 and EML5 is a good idea– if you use light sails!

    Going to Mars is going to require an appropriate amount of mass shielding to protect astronauts from excessive exposure to cosmic rays and major solar events. They’re also going to need a spacecraft that can produce some sort of artificial gravity.

    Utilizing lunar water resources for drinking, bathing, food preparation, the production of air, the production of fuel, and for mass shielding interplanetary habitats from excessive exposure to radiation is the fastest, cheapest, and simplest way to get humans to Mars in the near future.

    Lunar resources are much easier to access than NEO meteoroid resources– if you have a fuel producing facility on the lunar surface already established– which is not that hard to do, IMO.

    For meteoroid retrieval, first you have to locate the meteoroid you want to capture, then you have to spend– a few years– trying to bring it back to cis-lunar space. And if the primary resources you’re looking to retrieve from a meteoroid are oxygen and water, then more than half the mass you’re transporting to cis-lunar space would be wasted!

    On the Moon, however, one SLS launch is all that is needed to deploy a couple of reusable cargo shuttles (~10 round trips for each vehicle with a set of restartable CECE engines), each capable of delivering approximately 50 tonnes of lunar resources to one of the Earth Moon Lagrange points. If you also deliver a few sets of CECE engine replacements (they only weigh about 160 kilograms each) with the cargo shuttles then perhaps 50 round trips may be possible for each cargo vehicle.

    So, in theory, the deployment of two lunar cargo shuttles– with a single SLS launch– could eventually transport as much as 1000 to 5000 tonnes of lunar resources to one of the Earth-Moon Lagrange points. And you can start transporting lunar resources to the Lagrange points almost immediately (in just a few weeks instead of a few years).

    Secondly, unlike a meteoroid, no massive amounts of wasted material would be transported to the Lagrange points from the Moon since the usable resource would already be extracted and processed at a lunar facility before being transported to a Lagrange point.


  2. Bleyddyn says:

    One question I’ve had for a while. What would be the best asteroid in-situ resource to use for SEP propellant? I think most of the existing designs use Xenon or Argon, but I don’t think either of those is readily available on asteroids.

    So is there anything on asteroids that could be used as a propellant in existing or near future ion engines?

  3. Jonathan Goff Jonathan Goff says:


    Good question! For almost all electric propulsion systems, Xenon gives you the best results, because ionization is typically an energy loss (ie it doesn’t get converted into kinetic energy), and Xenon has the best ionization energy per unit mass.

    That said, MSNW (of Redmond, WA) has a cool potential workaround that they’re developing under some AFRL and/or NASA contracts. Basically, they ionize and accelerate the plasma using their plasma thruster. Then they inject neutral particles downstream (afterburner style) where they get ionized by the plasma via charge exchange collisions. The now-neutralized particles from the original plasma keep going in the same direction and speed they were going before, but now you can accelerate the now-ionized neutrals. So you get at least two ionizations for the price of one. Using that trick they think they can get the overall thruster efficiency (input power divided by jet power) of something like water or hydrazine up close to what you can do with Xenon with more traditional thrusters.

    So if you want an ISRU-refuelable SEP system. Good old water may be your friend, once MSNW has their technology matured and flown.


    [I should note that we’ve done work with MSNW on these thrusters, so once again, I’m not completely unbiased on the topic.]

  4. Bleyddyn says:

    Thanks! I’ll definitely keep an eye on them.

  5. I agree. My own reasons were published a while ago in Space News, What is Wrong with Retrieving an Asteroid.

  6. jccooper says:

    HSF people don’t like the ARM because it isn’t cool enough, and the only particular reason to do HSF is because it’s cool–and to prepare for more HSF in the future.

    But considering that asteroids are one of the few real targets for a legitimate off-earth economy I think it makes a surprising amount of sense to grab one and study it and learn to work with it in situ. SLS and Orion (or humans in particular) may not be the best way to do it, but if the Senate wants to fly big rockets for pork purposes anyway, it’s not a bad use. Beats flying around the Moon for no reason.

    So I hope it survives. The advance in asteroid mining and planetary defence would be great. It may even happen, as it’s the only plan for Orion that doesn’t involve a new multi-year, multi-billion-dollar human vehicle (that is, neither a Mars cruise stage nor a Lunar lander). I’m just disappointed they’re not doing several at the same time: there’s multiple classes of asteroids of interest.

  7. “One question I’ve had for a while. What would be the best asteroid in-situ resource to use for SEP propellant? I think most of the existing designs use Xenon or Argon, but I don’t think either of those is readily available on asteroids.So is there anything on asteroids that could be used as a propellant in existing or near future ion engines?”

    That’s why light sails should be used to retrieve meteoroids. They don’t have to use any propellant!

    Also, because of the potential use of such objects for acts of terror, 10 meters is probably the maximum diameter that should be allowed to be introduced into cis-lunar space.

    But there’s no reason why larger NEOs couldn’t be placed in orbit around Venus and Mars to be processed by factories there with their processed materials later being exported to cis-lunar space.

  8. Paul451 says:


    1 & 10: If having a nearby small asteroid was really valued, you’d bring it much closer. Instead, ARM is designed to leave the sample precisely and arbitrarily as far away as SLS-Orion is capable of operating. I think this artificiality is what annoys people who would otherwise wildly support an asteroid mega-sample return mission. That leads to the suspicion that everything about the mission except “Justify SLS” is expendable.

    The arbitrary location also makes any follow-on work by anyone else unnecessarily harder and more expensive.

    Politically, I doubt the agency will allow private robot-only missions to the sample, post-ARM. (This will also cause the death of any other unmanned asteroid/comet missions from NASA for the next decade. No rivals will be allowed, even if funding was there. And if ARM is then cancelled by a future Administration, it means asteroid research has been ruined for 20 years.)

    2, 4, 7 & 8: The SLS/Orion development and operations costs will likely eat any budget you might need for any actual ISRU research or the MSNW work. And a DSH is exactly the sort of thing that would be cancelled early. Likewise any potential lunar follow-on.

    3: ARM is often presented as a “Hey, if we’re doing SLS/Orion anyway, we might as well…”, but it’s not. There’s nothing funded in SLS/Orion that is useful to the sample-return aspect of ARM. Since NASA’s overall budget isn’t going up, you’ll therefore need to take that funding from something else. And if you aren’t taking it from HSF, then you’re taking it from science. So yes it’s a lovely big sample, but it’s going to kill a Europa mission or the next Mars rover or, much more likely, a whole bunch of Earth science and solar/astro science missions. Any wonder they’re hostile?

    Now, if the proposal was to kill SLS/Orion and instead fund one of these ARM sample returns per year for a decade, I’m sure you’d get a lot more support from the science guys; even if it meant having those smelly astronauts doing the final sampling in LEO (via commercial crew flights and either ISS or a small commercial DSH-like platform). And you’ve guaranteed a bunch of support from the commercial-space guys. And the robot guys. And the nano-sat guys. And ESA/JAXA joining in. It’d be a real science program, and a real tech dev program, and a real target for other people, for stuff not thought of yet. And you’d be able to pay for it (which is always nice.)

    5: This is the only saving grace that I can see. A large-payload SEP tug would be a very useful tool.

    (I keep trying to see a way of doing the mission without the tug, because at some point there will be a bunch of people trying to find a way to do the mission without it in order to cancel it and eat the funding. And if a way exists, the tug will be cancelled. The only thing I can see so far is that the sample size will be drastically reduced to shrink the size of the tug.)

    6: I worry that we’re seeing a familiar “dog piling” on ARM, where everyone tries to attach their favourite hobby-horses to the Big Project, and the result distorts or blows out the requirements (and hence the schedule/budget) even though 90% of those extras get cancelled before it flies anyway. (See also: Shuttle, ISS, NGST, VSE, etc.)

    7/9: The sample isn’t large enough, and will be too well wrapped, to provide that kind of experience. The only experience gained would be the sampling process in Option-B, and again, that’s a pure robotic mission. If Option-B proves even mildly difficult, it’ll be killed to protect funding of the SLS/Orion side.

    tl;dr – ARM has great potential… all of which will be stripped away to feed the SLS-monster.

  9. Paul451 says:

    “Also, because of the potential use of such objects for acts of terror”

    {sigh} Seriously? I can understand scientifically illiterate people, journalists and politicians, coming up with this kind of nonsense, but not on a site like this.

    The Chelyabinsk meteor was 12-15 thousand tonnes. The sonic shockwave broke a few windows, knocked over a wall, bunch of people were hurt by flying glass. That’s it.

    ARM is a bag of loose rocks, gravel and dust 1% of that mass (and 1/3rd the Ek/kg). Additionally, the ion drive and any attitude control systems provide nowhere near the thrust to give fine control during the reentry. Which means your impact zone is going to be determined by random variations in the upper atmosphere along your reentry path. Your impact will be somewhere random along a zone several hundred kilometres long if you’re lucky and if you really know what you’re doing. Oh, and what does reach the ground will be at atmospheric terminal velocity, not orbital velocity.

    So – It’s tiny. You can’t aim it. 90% of the material won’t reach the ground. And with what does reach the ground, you’d get the roughly the impact damage damage of throwing gravel off a tall building.

    But hey, let’s all panic anyway.

    “close enough that almost any spacefaring country or business in the world can reach if it wants to.

    Hmmm, interesting test case for OST. The asteroid or B-samples will be entirely wrapped/contained. It will essentially be a full owned sovereign facility, under the definitions of OST. However, it contains a “natural body” (or material thereof.) If another nation did their own sampling (even robotic) from the ARM-asteroid, without asking US permission, would the US have a case to cry fowl under OST? (Especially if the uninvited guest didn’t harm any US equipment, only used the same access panels in the bag/box.)

    Because if the US has a case to assert it’s sovereignty over the “facility”, then property rights under OST would be a solved issue. You still may not claim a body you are not in possession of (so no formal titles), but once you establish a “homestead” (in the libertarian sense), you have full sovereign rights over the material under your control.

    That would make the rest of OST the perfect treaty. Respect each others stuff, don’t interfere with each other’s activities. Help each other in emergencies. Return mis-landed astronauts and equipment from wherever it ends up. The only issue is launch-nation-sovereignty over activity. And even that might be resolved with launch sites in flag-of-convenience nations if reusability becomes routine, even better if sea-launch becomes routine.

    (Quoting) “a pathetic attempt to reengineer the Solar System to make it handicapped-accessible for SLS and Orion”

    I’ll admit I giggled when I read that.

  10. Paul,

    1- Regarding your first point, I think the lunar DRO actually makes a bit of sense. Getting something that big down into LEO is non-trivial. For the smaller boulder missions, you maybe could do it using something like the magnetoshell aerocapture technology we’ve been working on with MSNW (it was sized for capturing a 60ton Mars craft into orbit), but I’m not sure if you could keep the deceleration low enough to not break the rock in the process. For the Option A choices, it would be even harder. You could spiral down in, but that would likely be a lot more delta-V than they’re currently planning for the mission. Is it possible? Maybe, but it isn’t as easy as it sounds. And a lunar DRO isn’t much harder to get to than L1 or L2. Sure it’s not LEO, but it’s not like it couldn’t be reached by commercial vehicles (manned or unmanned).

    The other big reason they want it in a lunar DRO is that it doesn’t require stationkeeping to keep it there. In LEO, you wouldn’t need stationkeeping that often (its density would be higher than ISS), but you would need some stationkeeping, or keeping it at high altitudes. Or it would end up deorbiting–and even though it would be lower energy than a real meteorite, I think people would freak out about the risks. Plus your odds of it being hit by space debris goes way up. Once again, no legitimate showstoppers, but I don’t think you have to be a total pansy to see that LEO might not be the best place to park something like this.

    As for whether NASA would let people visit it, that’s purely speculation on their part. I’d actually be surprised if they didn’t–they’d be able to claim all sorts of browny points for “public private partnerships” etc.

    2- I agree that SLS and Orion are crappy wastes of public resources. But I don’t think necessarily that they’ll suck all the air out of the room. Now, I doubt NASA will invest properly in ISRU, but NASA isn’t the only entity involved. And once again, they like being able to claim credit for public-private partnerships when they can.

    3- I don’t think ARM has any chance of successfully raiding science’s budget. More likely technology’s budget, or hoping for a plus-up that’s unlikely to happen. There actually is a budget for Exploration Technology. ARM has spent $100Mish so far, w/o raiding science at all. If they had a way to keep the ARM spacecraft under $1.2B, they’d only need an extra $100-200M/yr to have it ready to fly in time.

    The right place to take it out of would be SLS and/or Orion, as you suggest. That would be my preference as well. There’s really nothing about a good ARM mission that needs either of those vehicles. Heck, you don’t even need Falcon Heavy or Delta-IV Heavy to make something like this work. I think it’s probably unlikely they’ll be able to get much out of either of those sources though.

    4- ARM itself is more likely to be canceled than the tug. Boeing has been lobbying for big SEP tugs for years, and NAC was pretty clear they’d rather have NASA build the SEP and ditch the ARM mission. No, this is one of the few things where SEPs are clearly superior for–no way you’re going to get back a large sample without one.

    5- Not sure I disagree with your tl;dr about what is most likely to happen. Honestly I think they’ll kill it sooner than that. I just wanted to defend the mission concept itself, because it is a useful concept that I feel is being tarred by its association with SLS/Orion, and the Obama Administration. I didn’t want to see a good idea go down without some sort of a fight.


  11. Paul,

    Re: the OST thoughts–I was thinking along the same lines, but didn’t want to necessarily draw attention to it, since that might freak out some policy people. But yeah, it would be a sample, and at least under existing precedence, NASA should own it point blank. But it would also be a moon. It would be a load of fun to see where that ended up going from a space-law standpoint. 🙂


  12. Paul451 says:

    “I think the lunar DRO actually makes a bit of sense. Getting something that big down into LEO is non-trivial.”

    Worse case and you need to send a whole new SEP tug out there to do the final stretch, still going to be cheaper than the SLS/Orion mission. And it leaves the ARM-payload in LEO, which makes it much easier for NASA HSF and other people to routinely access it. (I’m particularly thinking off all the stuff that nano-sat and small-sat-robotics guys could whip up on a trivial budget. Getting to lunar orbit automatically throws them into “major program” territory. That severely constrains the genuinely novel (high-risk) research that would be done. Contrast the many cheap and cheerful nano-sat mission flown with the difficulties of the GLXP competitors.)

    (There are also low delta-v chaotic orbits that are available to unmanned missions that are not available for HSF due to the time and repeated passes through the Van Allen belts. )

    “In LEO, […] you would need some stationkeeping,”

    SEP already provided. Extra fuel every few years. Done.

    (Good platform for orbital refuelling research too. It’s right there.)

    “As for whether NASA would let people visit it […] they’d be able to claim all sorts of browny points for “public private partnerships” etc.”

    I strongly suspect that the low cost of robotic visits by even friendly foreign governments or private US businesses would be politically embarrassing to those defending SLS/Orion budgets. Hence I suspect there’ll be a lot of pressure against letting “them” touch “our” asteroid. Likewise any NASA robotic missions to asteroids or comets will be blocked from now until after ARM’s HSF mission (and probably some time after.) Which means if Orion-ARM is funded and then later cancelled, US asteroid/comet research is set back at least a decade. That’s probably one of the things that many on the science side are worried about, they’ve seen that kind of politics played out with the Shuttle payloads.

    IMO, this wouldn’t happen with LEO-ARM. Even though HSF visits would cost much more than robotic ones, you would achieve so much more and be able to try so much more, that there’d be no more complaints than the normal background manned-vs-unmanned bickering. And since the HSF visits wouldn’t be part of a single Big Mission, and would happen more often, they’d be more like ISS and largely fly under the radar. (Plus many of the costs would be hidden in the ISS budget.)

    “I just wanted to defend the mission concept itself, because it is a useful concept that I feel is being tarred by its association with SLS/Orion, and the Obama Administration.”

    I agree that the basic concept of ARM is good. But the harm from its “association with SLS/Orion” isn’t just reputational, IMO it actually makes ARM worse as a mission.

    You don’t want the idea behind ARM tainted by association with SLS/Orion, but I don’t want SLS/Orion’s reputation polished by association with otherwise useful ideas. I’m particularly disturbed by the “Well, if we have to have SLS/Orion, because Congress, then we might as well stop arguing about it and try to get some useful missions” meme I’ve seen going around. I don’t want to let a bad idea go unchallenged at every opportunity.

  13. DougSpace says:

    Why is a lunar gateway useful?

    For a cis-lunar transportation infrastructure, just shoot new landers directly from Earth to the lunar poles and introduce them into the transportation system. Each new lander could carry small, high-tech or high-precision items that cannot yet be produced on the Moon.

    By human-rating the automated landers, crew could repair ice harvesting equipment and extract and process lunar metals to expand the telerobotic workforce and start to reproduce parts for equipment to expand the base. Crew needing medical help could receive it either on the lunar surface or be shipped back to either LEO or Earth. No particular need for a medical facility at EML1/2.

    Transfer of propellant could be done directly between craft without needing a propellant depot in between. Craft heading beyond LEO would gain the most by either receiving propellant or docking and being pushed by an OTV fueled from lunar ice.

    So, why go through the hassle, delay, and expense of establishing an EML station?

  14. DougSpace,
    I guess it’s a matter of perspective. Do we need depots or way stations? No. Do we need gas stations here on earth? Not really. We could totally just use siphon hoses and jerry cans. It’d be inefficient, but then you wouldn’t need that complex infrastructure, right?

    On a more serious note, when you’re talking about automated landers, telerobotic ice miners, and ISRU generation facilities with enough power and equipment to turn useful amounts of ice into liquid oxygen and liquid hydrogen propellents, the cost of developing a depot is pretty much round-off error. Plus it’s pretty darned useful. Without a depot you have to carry all your fuel transfer, storage, and handling hardware with every vehicle. With depots, you can keep the hardware that needs to be pushed through large maneuvers as light as possible, minimizing wasted propellant. And it’s not just fuel transfer and storage hardware. It’s also the rendezvous/berthing hardware–with a dedicated facility you can offload a lot of stuff from the moving vehicles to the stationary platform.

    Do you have to do it that way? Not really. Could you save some tiny fraction of the overall development cost by skipping that step? Sure. But I think you’d be penny-wise, pound-foolish to do so.

    Just my $.02


  15. DougSpace says:

    Thanks Jon. I’m actually thinking about the earliest phase of developing a cis-lunar transportation system here and how much would be saved by going immediately for the lunar ice rather than spending the money and time to develop depots at potentially multiple LEO inclinations. Coming from lunar distances, the first OTV could provide propulsion service to all LEO inclinations.

    One of the objectives of propellant depots would be to support access to the lunar surface. I’m suggesting that we can access the lunar surface immediately with a Falcon Heavy class launcher for one-way uncrewed landers initially and that by harvesting and processing lunar ice for propellant, we begin to get the benefits of a cis-lunar transportation infrastructure starting with the first launch and getting lunar access to boot.

    Provided that the initial lunar lander(s) was Xeus-like (i.e. LH/LOX) then one could deliver roughly 7 tonnes of solar panels and teleoperated hardware with the first mission. At one part per 18 concentration of ice at Caebeus Crater, it wouldn’t take long for a single fairly large ice harvester to steam out enough water to refuel the initial lander. So, “ISRU generation facilities” sound far larger than what I’m talking about.

    For a vehicle-centric model, the propellant storage tanks would be the propellant tanks of the vehicles themselves, so no extra mass there. The landers would initially serve as their own storage tanks in the permanently-shadowed craters and flights is cis-lunar space would proceed immediately without spending a lot of time being heated in cis-lunar space such as would happen with a propellant depot-centric model. So long-duration cryo coolers wouldn’t be necessary initially. Landers should have docking structures anyhow if they are going to be carrying lunar-derived propellant into the cis-lunar transportation system.

    I’m not sure that the terrestrial gasoline analogy is helpful. Each gas station needs to serve thousands of cars whereas any GEO comm sat (for example) needs only the propulsion service (i.e. not propellant transfer) of a single OTV on a single Cis-lunar Circuit. It is true that one would need three or so OTVs for any Constellation-class mission BLEO. But those missions may be quite rare and a cis-lunar transportation system scaled up to include three OTVs would still be about the launch costs of a single LEO depot serving only a single inclination.

  16. john hare says:

    If you will run a few trades, you might see some of the depot advantages for even your very early mission. The Lunar Orbital Transfer and Lunar Orbital Insertion burns will deplete a fairly large tank. Your lander can leave that stage with its’ tanks in Lunar orbit as a depot. Several up and downs by the lander can refill the depot to support many follow on landings by vehicles that arrive in Lunar orbit dry.

    Some of these lander can be of a size not possible without refueling in Lunar orbit assuming readily available launch vehicles. Doubling the available lander size is not trivial.

    Further use for an early depot is prospecting support. The lander leaves your propellant facility in a hop to another Lunar site using two near orbital class burns. Then it can climb to the depot with an orbital burn to be refueled for another series of landings without having to return to your propellant production facility. This has prospector hoppers requiring 3,000-4,600 m/s DeltaV rather than 6,000+ for a return to production facility every time.

  17. Hop David says:

    “Worse case and you need to send a whole new SEP tug out there to do the final stretch”

    The Keck folks think they can park a rock in lunar orbit for around .2 km/s.

    There are lots of rocks that already slowly pass by the earth-moon neighborhood. If the heliocentric orbit of some are just slightly tweaked, they can be nudged to a closer fly by of the moon where a lunar gravity assist can drop a hyperbolic orbit into an elliptical capture orbit.

    The captured rock would have a C3 close to zero and adjusting this high earth orbit wouldn’t take a lot of delta V.

    Moving this rock from a high earth orbit to LEO is a very different scenario. With low thrust ion engines you wouldn’t have a Hohmann ellipse but rather a slow spiral that would take around 7 km/s of delta V. If the rock is a million tonnes, you would need around 250,000 tonnes of xenon (assuming an exhaust velocity of 30 km/s). This “last leg” SEP would be a much different animal that the Keck SEP for fetching rocks from heliocentric orbits.

  18. Hop David says:

    Thank you Jon! I’d like to see the ARM mission for the reasons you mention. It’s tough holding a minority opinion.

    Regarding 6: The delta V for deflecting a rock can be much lower than what’s needed for parking a rock. I think it might be possible for an ARM style vehicle to deflect a Tunguska sized rock and even more likely it could deflect a Chelyabinsk sized rock.

  19. Robert Clark says:

    A hypothetical question:
    NASA has said we can’t return to the Moon because a lander would cast $10 billion, which we can’t afford. Suppose hypothetically a lander could be developed for a few ten’s of millions of dollars, an amount barely in the noise. Would NASA do it? Or would it still WANT a $10 billion lander which it can’t afford?

    Bob Clark

  20. LocalFluff says:

    I just heard you on the Planetary Radio.
    The reason so many argue against ARM, is because it is so easy to do so against a bad idea! Some comments to your points:

    4. & 5. The arguments against ARM are not arguments against SEP or space habitats. Instead, the bottom line is simply:
    Forget about that useless little rock!

    3. & 7. Asteroid researchers and mining industry prospectors want diversity, a survey of many asteroids. That is actually what the term ”a large sample” means. It doesn’t mean that a single sample is large, but that there are samples from a large number of objects has been studied. There are thousands of meteorites in museums. Option B is especially worthless because it will not even return a mini-asteroid. It will return a boulder from an asteroid. They obviously form in different ways than do real asteroids.

    2. & 9. A 3 to 5 meter diameter rock is too small for mining. And SEP doesn’t scale well. SEP cannot be used to move a real asteroid, other than slightly diverting its trajectory for planetary defence. Mining will take place on real asteroids in their natural orbits. A test bed mission should perform a series of studies and experiments there, compare with Rosetta (for which SEP would not be enough).

    8. Availability with launch windows every day is a advantages of the Moon compared with any other celestial object. Doesn’t an object om DRO lose that advantage? Isn’t that a bad thing for a gateway? And why a gateway to the Moon to begin with? One goes there directly, and resources are (hopefully) available on the Moon itself.

    1. Just throw it down through the atmosphere! It would have less than 1% of the volume of the 20 meter diameter Chelyabinsk meteor, so it cannot hurt anyone. Then we can put it in a museum next to the thousands of natural meteorites we’ve retrieved by using gasoline trucks. Could it get more “accessible” than that?

  21. LocalFluff says:

    You said on Planetary Radio that ARM is a partisan issue. I don’t live in the US, but it is obvious even to me that it is not. The current administration cancelled Constellation because it wanted to show “Change”. Every administration does that. So Obama said “been there, done that” about the Moon, probably because he was incompetently advised that NASA could send humans to an asteroid instead. ARM is the “pretend-to-send-humans-to-an-asteroid-to-cover-up-the-blunder” mission. Not even Obama can be happy with how this has turned out. And ARM will be canceled by the next “Change” administration, even if it too is Democratic.

  22. Im sorry to bring pessimism to this wonderful and inspiring discussion. But if we are going to see any exciting space developement during my or our lifetimes (Im 33 atm) there has to be a radical change in public opinion about space exploration.. Something like that the Ceres bright spots are not a natural phenomenon but something else.. Now that would surely bring som cash to the table.

  23. Pingback: Up in ARMs for No Good Reason | Selenian Boondocks

  24. Robert Clark says:

    I was completely opposed to ARM until I did a simple calculation that showed that with orbital propellant depots at both departure and arrival points that flights to the Moon, Mars, Venus, asteroids all become actually easy. In fact the mass that needs to be transported to LEO decreases by two orders of magnitude. For instance instead of the ca. 1,200 metric tons for a Mars mission by the NASA DRA 5.0 all you would need is a single ca. 10 mT dry mass booster, a la the Falcon 9, Ariane 5, Atlas 5, Delta IV, or Soyuz first stages to do all the propulsion from LEO departure to planetary landing to liftoff to return to Earth:

    The Coming SSTO’s: Applications to interplanetary flight.

    Then ARM accomplishes the key goal of making manned flight to other inner solar system bodies routine, or at least as routine as flights to the ISS.

    Moreover, since you would have virtually unlimited propellant you could make these flights at travel times of weeks instead of months, solving the problems of long zero-gravity and radiation exposure by using existing chemical propulsion alone, no new nuclear power rockets required.

    And for the Mars mission, by refueling in Mars orbit on arrival you could also make a fully propulsive landing on Mars, solving also the problem of landing large mass on Mars.

    In fact practically every technical difficulty that has been raised about a manned mission to Mars is solved simply by having propellant depots at both departure and arrival points.

    A key task now then is to identify those asteroidal or cometary fragments near Earth that would have large amount H2O, CO2, and CO for propellant.

    Bob Clark

  25. Paul451 says:

    (I missed this comment)

    “Moving this rock from a high earth orbit to LEO is a very different scenario. With low thrust ion engines you wouldn’t have a Hohmann ellipse but rather a slow spiral that would take around 7 km/s of delta V. If the rock is a million tonnes, you would need around 250,000 tonnes of xenon (assuming an exhaust velocity of 30 km/s).”

    Assuming 3 tonnes/m^3 (which is typical of solid rock), that is an 80m diameter sphere. We’re talking about ARM. And ARM is not going to be returning with an 80m asteroid.

    Typical “best case” number is around 8m. More realistic is around 3-5m. Say 4m. So about 100 tonnes if it is solid. Less if it’s fluffy rubble. That brings your number down to 25 tonnes of Xenon. (Or more realistically, 30t of Krypton.) However, that also assumes a worst case 7km/s delta-v, and without humans on board, you can play with multiple interactions with the moon’s gravitational sphere of influence which should drop that requirement quite substantially if you are willing to accept long drift times (and there’s no reason not to.)

    “The current administration cancelled Constellation because it wanted to show “Change”. Every administration does that.”

    No, Obama tried to cancel Constellation because it was overbudget and falling more than one year per year behind schedule. It was an unaffordable program.

    “So Obama said “been there, done that” about the Moon, probably because he was incompetently advised that NASA could send humans to an asteroid instead. ARM is the “pretend-to-send-humans-to-an-asteroid-to-cover-up-the-blunder” mission.”

    Obama’s budget request was to channel funding into alternative technologies (like new engines, orbital fuel depots, long duration deep space habitats, and so on.) That is where the humans-to-asteroid capability was meant to come from.

    That request was killed by Congress and replaced with the SLS monster. (Essentially 2/3rds of Constellation resurrected.) That meant any HSF mission was limited to cis-Lunar at best. And that is why NASA is limited to fake missions like ARM.

    Understand? It’s a direct consequence of the limits inherent in SLS/Orion. And SLS/Orion is not something Obama wanted or asked for. Unless the next President can kill SLS/Orion, this situation will not change. ARM may be killed off, but that doesn’t magically make SLS/Orion capable of more than lunar orbit, nor free up funding for lunar landers/bases or whatever it is that you want.

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