Laundry in Microgravity

The lack of laundry facilities in orbit was brought up recently and it occurred to me that  this lack seems to be more for lack of trying than real difficulty. The lack of trying that I suspect could be because it is more trouble than it is worth to wash clothes on the ISS when it is a relatively minor mass and volume is to just throw away the dirty and ship up more from time to time. Eventually with enough human activity in LEO and BEO though, the choices will be wash, wear dirty until worn out, make more on board, or ship increasingly large quantities of disposable clothing from Earth. I think option one will be desirable at some point.

The problems with washing clothes in microgravity as I understand it are more to do with the chemicals normally used in detergents than with mechanical problems. The chemicals from the detergents and most soaps are very unwelcome in a closed environment as any environmental contamination is a major issue. It’s not like the air conditioner is going to vent problems outside the laundry room.

To me, the likely solution will be more mechanical with plain water than the soaps and softeners we use here on the ground. Something along the lines of pressure cleaners allied with old style wringer washing methods.

laundryIn this cartoon, he dirty laundry is fed into the rollers on the left. The rollers seal the entrance and feed the clothing into porous chain that travels through the cleaning area where it is hit from both sides by staggered nozzles that are calibrated to have enough pressure to knock dirt loose from the clothing but not enough to damage it. The clothing exits the chain through a second set of rollers that squeezes  out most of the excess water and seals the exit from the rest of the ship.

During this the fluids in the wash area are continuously recycled through a liquid air separator/dirt filter/pump so that the same water is used indefinitely. This is represented by the oval in the lower section of the box. Second function of the filter/pump/separator is to maintain a lower pressure inside the machine than in the rest of the station so that there can be no contamination escape to the living area.

Posted in Uncategorized | 13 Comments

Random Thoughts: First Pass Analysis of a White Dragon/Xeus Lunar Sortie Mission

After yesterday’s SpaceX announcement of having booked two customers for a Apollo-8 style mission around the Moon and back, using Falcon Heavy and Dragon V2, I got thinking about ways to take the next step in lunar tourism–surface missions. Now, this “White Dragon” mission around the Moon makes a lot of sense for SpaceX even though Elon doesn’t care that much about the Moon:

  1. Hardware-wise, there really might not need to be much new work beyond what they’re already doing for Falcon Heavy and Dragon V2. The flight is short enough relative to a worst-case ISS delivery that with 2 passengers instead of 7, the ECLSS is probably already adequate. The heat shield, due to minimum gauge issues with PICA-X, is way overbuilt for LEO return, and thus is likely more than adequate for lunar return.1 The Falcon Heavy should have the throw-mass to do the mission. So they can do this without likely requiring dramatic hardware development beyond what they need for normal FH and crewed Dragon V2 flights.
  2. It’s revenue–even if it costs say $170M/flight (take a ~$140M cost for a four-person ISS delivery, subtract 60M for the Falcon 9 and add 90M for the Falcon Heavy), they can still get takers at a price of ~$85M each. Heck, even if they’re selling it through Space Adventures for $100M each (with the $15M delta being Space Adventure’s cut), this is still a good deal for SpaceX. They only have to convince two people, and they get double the revenue of a Falcon Heavy flight. That’s not quite as good as selling a several flight campaign for Iridium, but it’s not too shabby, especially if Space Adventures or someone like them is bringing the passengers.
  3. There’s a good chance it could turn into a steady stream of revenue. As I’ve previously discussed here, one of the main limitations on space tourism has been availability of spare Soyuz seats, not the price. And when you add the novelty of a lunar mission, I wouldn’t be surprised if they could get a steady White Dragon mission every year or every other year at worst. Even if the price doesn’t come down much over time.
  4. It gets them experience they want for future deep-space operations. Testing reentry heatshield wear, ECLSS behavior on long missions, how their electronics hold up outside the magnetosphere, etc.

So for all those reasons, it makes sense for Elon to say yes to White Dragon missions, even if he doesn’t care at all about the Moon. If someone wants to give you money like that, and it doesn’t cost you much to service them, why the heck not?

But as soon as you start talking about lunar landing missions, the situation changes. Now you’re talking significantly more complicated missions that are going to take non-trivial amounts of new hardware, that will unlikely be directly relevant to Mars missions. Barring someone dropping a bunch of money in Elon’s lap, I’m not sure it would make sense for SpaceX to do the mission by themselves. But, it might be an intriguing joint mission for SpaceX and ULA, assuming for sake of argument that Elon would be willing to work with his closest competitor, and that Boeing and LM wouldn’t torpedo something that could be seen as a direct competitor to SLS/Orion.

So, assume away the political challenges for a second. Could you realistically make a lunar landing mission work with a combination of SpaceX and ULA hardware? After running the numbers, I’d say tentatively yes.

Here’s what the SpaceX stack would look like:

  • Falcon Heavy
  • Large LOX/LH2 tanker (~39.4mT of prop, ~7.2mT dry)
  • Dragon V2 on top

The ULA stack would look like:

  • Vulcan/ACES 546, with the ACES having a Xeus landing kit (~1mT)
  • Small short-duration two-person crew cabin (estimated ~2mT)

Falcon Heavy would launch first, placing the crew and tanker in orbit. Vulcan/ACES would then launch shortly thereafter, with ACES performing a rendezvous with the SpaceX stack, transferring ~39.4mT of prop over (basically filling the ~70mT ACES stage). The Dragon would then separate from the tanker, and connect to the ACES/Xeus stage. The ACES Xeus stage would do a TLI burn for the stack, followed by an insertion into LLO. Dragon would then be left in orbit while the astronauts are flown down to the lunar surface by the Xeus stage, hang out for a while, and then they get flown back up to LLO by the same Xeus stage. The Xeus stage would then dock with Dragon and perform the LOI burn, sending the whole stack back to earth.

Using these assumptions, it looks like the concept closes (here’s the first-pass analysis spreadsheet: WhiteDragon-XeusCalcs), but without as much margin as you would want, and without enough propellant to propulsively capture Xeus back into LEO.

Here are some ways that the concept could be improved:

  1. Be more aggressive on the lander cabin design–2mT is actually half the dry mass of a Dragon Capsule, in spite of not needing anywhere near the capabilities–no need for a trunk or a reentry shield, no need for RCS engines (ACES and Dragon V2 both have plenty of maneuverability). So you might be able to whittle that down a bit.
  2. Use chilled propellants–between the Vulcan/ACES 546 leftover propellant and the Falcon Heavy tanker propellants, there’s actually more propellant than will fit into a stock ACES stage at normal boiling point densities. Chilling the propellant would both surpress boiloff losses, and would also allow you to cram a bit more propellant into the stage. This is already something SpaceX does for Falcon 9, so it isn’t that crazy.
  3. Stage in EML2 and have the Dragon V2 perform the earth return burn leaving Xeus at EML-2. The question is how much propellant is needed for rendezvous, reentry, and landing. By my BOTE calcs, assuming a 320s Isp on the regular Dracos, you should be able to get ~620m/s of delta-V out of Dragon V2, and you’d only need ~150m/s for the earth return/powered swingby maneuver. But you’d now be talking about a much, much longer mission.
  4. Jettison the lander cabin and/or Xeus kit prior to the earth return burn.
  5. Have the lander cabin actually be a separate lander/ascent stage. Have the ACES stage not have a Xeus kit, but do an uncrasher maneuver where the crew cabin stage separates right before landing. the ACES stage returns to lunar orbit w/o the ascent stage, and reconnects with the Dragon capsule. The ascent stage lands, the crew hangs out for a bit, and then launches again back up to the waiting Dragon and ACES stages. The crew cabin/ascent stage is left in LLO before ACES takes Dragon back to Earth.
  6. Down the road adding refueling in LLO or EML2 or on the lunar surface would make the whole thing tons easier–you’d need another launcher, but that would all of the sudden give you the margin needed to do much more ambitious missions if you didn’t have to haul the prop all the way from LEO and back.

There are probably other variations on the theme. But the interesting thing is that this concept comes close to closing using Falcon Heavy, a stock Dragon V2, with the main pieces of new hardware being a propellant tanker section for Falcon Heavy2, the Xeus kit for ACES, the fuel transfer hardware, and the crew cabin.

If you assume $150M for the Vulcan/ACES 546 flight ($90M for the bare Vulcan/ACES plus six strapons at $10M/ea), $170M for the FH + Dragon V2, $20M for the tanker/transfer hardware, and $30M each for the Xeus kit and the crew cabin, you get about $400M/mission, or about $200M/person (plus markup if your brokering it through Space Adventures). Call it an even $250M/person ticket price. That’s about 1/3 of what Golden Spike was targeting…

Anyhow, rockets aren’t legos, who knows if Elon and ULA can play nice with each other, I have no idea how ULA would get its parents to go along with a scheme that enables lunar landings without needing SLS/Orion. But the concept comes really close to closing, so I thought I’d put it out there.

Posted in Commercial Crew, Launch Vehicles, Lunar Exploration and Development, Propellant Depots, Random Thoughts, Space Exploration, Space Transportation, SpaceX, ULA, YHABFT | 51 Comments

Refueling for the Secondary Mission

It is fairly obvious that there are many benefits to having refueling capabilities in space. Perhaps not to the monster rocket fanatics with blinders and a few others, but to most of us it approaches no-brainer territory. The problem is getting to the first egg. The first bird we would accept as a chicken came from an egg, but that egg did not have to be laid by a bird we would accept as a chicken. Mules do not have mules for parents. The first refueling capability doesn’t have to have depots in the business plan, perhaps a buddy tank for starters.

The problem with getting refueling capability in space is often called a classic chicken and egg problem. Without a depot there is no refueling capability or reason to build vehicles to use it, and without the vehicles to use it there is no reason to build a depot. Dual launch architectures try to get around this by designing missions around a propellant launch and a mission launch. So far, this hasn’t worked well either as the mission planners try really hard to avoid boxing themselves into a corner where if either launch  fails, the mission fails.

One possibility hinted at in comments a while back is to have the primary mission fully capable of success if the primary launcher works properly. Then have enhanced secondary capability if the propellant launch succeeds and can top off the tanks in the primary. It took me a while to wrap my thoughts around the concept, after which I started working it over to see what I could think of. I can’t give due credit to the original thinker because I didn’t really grasp it until days later, just that it was somewhere in the 40 depot posts by Jon Goff and hundreds of comments associated with them. The originator can chastise me in comments  for not digging back for is name.

So this is my take on the idea. A vehicle arrives in LEO with payload for LEO. It hits the refueling vehicle either before or after placing its’ primary in the correct orbit. It off loads any excess propellant it managed to bring up if it is going to deorbit, or if it simply has excess for the secondary planned mission(s). Alternately it accepts enough more propellant to accomplish other missions that are non-critical to the primary mission.

The secondary missions suggested were along the lines of deorbiting various dead satellites. Surveying satellites with minor issues with the intent to design possible repair missions. Rendezvous with satellites in useless orbits and boosting them to the proper orbits. Creating the capability of the upper stage herding dead GEO sats after a GTO burn for the primary customer. Testing servicing options that would be too expensive for a dedicated launch.

The whole point would be to have some capabilities in place and in use for the cost of one launch that did not have to satisfy any customers other than the company that launched it. It would be replenished with excess propellant in vehicles that didn’t need all they hauled up. It would refuel various company vehicles that were scheduled to do extra work for revenue. The refueling wouldn’t have to be a maximum top off, just a calculated amount for individual missions. By using the capability in house, the problem of selling to and satisfying outside customers goes away. By not putting the capability in the critical path, the primary customers should have very few concerns about endangering their ROI.

It would seem that a capability could be started in the two digit millions. It could be very crude with perhaps LOX only to start, or LOX/Kero, or hypergolics, just as long as it fit that particular companies’ business plan.

Later on it might be possible to put this in the critical path of missions because a solid experience base and track record had been built up. Then after that it should be much simpler to get true multi-propellant depots up and running with whatever the market expresses a need for.

Posted in Uncategorized | 17 Comments

Random Thoughts: The Difference Between a Base and a Settlement (by Doug Plata)

There was an interesting comment by Doug Plata a few days ago that I wanted to repeat as a blog post. Background was discussing the idea of long-term stays on the Moon, similar to my old Lunar One Way to Stay (for a while) concept:

I would also like to point out that extending crew stay really blurs the line between what is a base and what is a settlement. I maintain that the real definition of settlement is when people are settling down. If people are settling down then that is a settlement. Settlements are not necessarily determined by size, economic independence, economic productivity, or the ability to have children. In particular, if retirees are moving away from Earth to stay, their settlement may start with a few people, the money for their settlement comes from their savings not from mining, and they will have no children with them. Yet, as the off-Earth retirement community grows, it will become increasingly obvious that it is a real settlement – Private housing, life support production, growing their own food, community meetings, perhaps it’s own governance structures, etc.

By way of historic analogy, consider a Mormon couple being sent to some distant valley to settle down, build their home, start growing their own food, raising animals, and preparing for the arrival for others. There may be no ore in the area and they may grow food for themselves. Relatives in the city might occasionally send them manufactured items that they couldn’t produce themselves. But they are settling and could rightly be recognized as being the first settlers for that area. Same with settling off Earth.

So, what does it take to do this initial type of settlement off Earth? It takes a habitat, adequate, ongoing life support including maintaining equipment, long-term protection from radiation and insufficient gravity amongst other things. These things are already needed for a permanent base. So, really, the only difference is that a base is a worksite and an initial settlement is a home. And a home is where you have a family. And a family can be as small as a husband and wife.

So, I for one think that the start of settlement doesn’t have to be many decades, trillions of dollars, nor need new, super massive rockets. Additionally, since a base can have a public (government) value and a base could be an initial settlement then a public-private program (e.g. Lunar COTS) could be funded largely by government funds yet also achieve the space advocacy goal of starting settlement.

I believe that this is very doable, I think that we should do it as a priority, and I think that it best that a free country, in particular the US, should do it before someone else finds out that the historic step of starting humanity’s first off-Earth settlement is as much a matter of choosing to do so rather than some huge technical or financial obstacle.

Food for thought.

Posted in Lunar Commerce, Lunar Exploration and Development | 10 Comments

Lunar Foxhole

Rereading some of the older posts on Lunar exploration, I ran into a lot of discussion on short term vs permanent outposts or bases. The assumption seems to be that short sortie missions will have minimal or even no radiation protection.

A quick thought is that a foxhole approach might be worth looking into for the short sortie or light mobile base concepts. Troops in the field that are likely to get shot at often dig or blast a small hole for shelter. Nothing is assumed to come from below, horizontal incoming is eliminated, and danger is reduced to vertical from above. Then the danger from above is often reduced with logs, sandbags, or even bodies in extreme cases.

With the foxhole model, it seems possible that a small hole can be created in the lower section of a crater to provide radiation protection from 80% of the sky not already covered by the planet. The hab section is lowered into the hole. Then the lander or wheeled vehicle can be parked over the top of the hole to help shield the remaining exposed directions from cosmic radiation. Solar radiation can be almost entirely eliminated from hitting the hab module.

With no high value real estate to destroy, or neighbors to annoy, the hole could be impact from a trans lunar projectile at 2,300 m/s. It could also be explosive, mechanically dug, or pneumatic  as Jon has posted about.

It seems to me that radiation protection for sorties or mobile exploration should be fairly simple except for time in transit.hab

Posted in Uncategorized | 23 Comments

Missing Destination, Missing Opportunity

It looks to be months from the time that SpaceX claimed to have solved the problem that caused the vehicle loss of September 1 until the actual return to flight. There are stories to the effect that the delays are to convince others that the vehicle is safe. One problem is that piles of paperwork and man years of investigation is less convincing than a flying vehicle. I don’t know if SpaceX has solved their problem or not and people far more informed than I am don’t know for sure either.

A convincing argument would be several vehicles flying with no other entity worried about insurance or loss of payload. Production of the Falcon IX is supposedly able to support a flight rate much higher than current practice would suggest. But flying empty vehicles for no revenue is an incredible waste.

An orbital depot would sure be a handy bit of hardware to have in place about now. While many of us have suggested at various times that a rocket under development would be ideal for delivering propellant, relatively few have suggested the same thing as a pure confidence builder after a mishap.

If an upper stage had been modified for use as a propellant depot totally owned by SpaceX, it could have launched after the 2015 vehicle loss as a confidence builder and alternate destination in times of over supply of vehicles. Over supply could be both from over production and reused stages. The modified stage depot would not have to be as sophisticated as the ULA ACES  as long as it was reasonably useful, and more importantly, in use.

It would seem that SpaceX could have launched a couple of tankers by now to build confidence after the September loss and followed it with revenue flights. Revenue flights sooner rather than later could possibly pay for the marginal cost of the confidence builder tankers. Payroll must be met either way, and little more red ink in one month to avoid several months of slightly less red ink per month could be a sound business decision.

I think most of us are already aware of the benefit of having 40-50 tons of propellant in LEO from the last three flights for use in a major mission to the GLAMs. (GEO, Luna, Asteroids, Mars)

 

Posted in Uncategorized | 23 Comments

Space-based Bitcoin Mining

Preface: if you’re a bitcoin expert, gird your loins because I’m probably going to be making a LOT of technical errors in this post.

So: space based solar power, but instead of beaming the power to Earth, we mine bitcoin with it.

OK. I’m indifferent to Bitcoin. I generally think it’s a dumb idea but that has some interesting technology. But it’s useful conceptually for imagining a straightforward way to turn computing power into money. Or, once progress on mining hardware slows down to the now-slow Moore’s law of 4 year doublings, a way to turn electricity directly into money while only having to transmit a relatively short amount of data.

What it is, very briefly, is a kind of “cryptocurrency” designed to do away with a central ledger, instead using a sort of consensus of many distributed computers as a ledger. Money is added to the money supply by “mining,” which in this case just means doing some pointless but hard and verifiable calculation until you randomly free up a “block” which is a bunch of bitcoins (each bitcoin is like $750 right now… easily subdivided, by the way). Mining difficulty is adjusted to keep the pace of adding to the money supply at a steady but very slowly decreasing rate.

I googled “bitcoin mining hardware,” and this popped up: https://www.bitcoinmining.com/bitcoin-mining-hardware/
The best hardware listed uses about 1200 Watts of electricity (all turned into heat) and produces roughly $4 of BTC per day and costs $400-something (…while consuming about $400 of electricity at 14 cents per kWh…). And weighs about 4 kg, so 300W/kg. So a dollar gets you 3 Watts of useful bitcoin mining, and it takes about 100 days for it to pay for its own hardware cost assuming mining difficulty doesn’t change. (Which is a terrible assumption, as more and more mining hardware comes online, the actual yield of bitcoin mining reduces to compensate.)

But only 33 cents per watt-used is great! That means we can replace that super expensive laser or microwave transmitter and receiver with cheap computer chips and radiators. And double or quadruple the power is available, too, because we don’t have all those transmission losses. But we do need to radiate all that heat away, so we’ll need a few more radiators, but in principle that’s not too bad. Radiators in this temperature range are like 100W/kg, so if we assume about 200W/kg for the solar power and a little extra for comms and pointing, we’re looking at about 50Wbitcoin/kg launched to orbit.

So at $100/kg to orbit (same price as the mining hardware, by the way!), and another $100/kg for hardware for a total cost of $200/kg, We have about $4/Watt-bitcoin. At 4 year replacement cycles (probably the power and thermal system would last a lot longer, but hardware would need to be updated), that’s about 11 cents per kWh of bitcoin processing, which is competitive (since it includes the mining hardware as well as the power). At longer intervals, even better.

But of course, this assumes bitcoin remains popular WHILE bitcoin mining hardware stagnates. The latter is not a terrible assumption, given that we’ve essentially reached the end of Moore’s Law (we’ll still see large improvements, but over longer timeframes, like 4 years instead of 2 years): http://arstechnica.com/information-technology/2016/02/moores-law-really-is-dead-this-time/

Posted in Uncategorized | 2 Comments

Indifference

I reread several times Jons’ post on NASA under the next administration that recommends against having NASA focus on anything one finds important. I think he made good points throughout and it should have made for lively discussion. I didn’t comment there as I didn’t have anything useful to add. I felt that I should have had strong opinions to throw out there, but couldn’t find them. A lot of people that used to jump in discussion of that nature were also conspicuous by their silence. Could it be because many of us have become indifferent to the flagship programs of NASA?

All of us know of good work by NASA in various programs. How long has it been since the NASA flagship program was the one that produced the good work? ISS, SLS, Orion and the James Webb telescope seem to be trudging along with the press releases at regular intervals celebrating some milestone or another. It is so hard for someone of my interests to see any of them leading to useful space settlement and development that indifference is probably the best to be hoped for. The alternative is to see them as roadblocks to progress and the enemy. I have enough on my plate without adding gratuitous enemies.

In response to someone calling for one of the flagships to be cancelled, Ed Wright noted that the congressional funding would just be diverted to another similar program by the congressman that kept the first one going. That’s just the way it is as SLS morphed from Aries, which derived from Shuttle, which kept the Saturn/Apollo teams together and so on. Tilting at that windmill will just lead to busted lances and bruises.

So what do I want NASA to do? I don’t know. I accept Jon’s point that it shouldn’t be anything I am passionate about. That is about as far as I can get. Some will no doubt suggest that NASA should put a base on the moon or some other favorite direction. Does anyone believe that ISS on the moon would be any more productive than ISS in LEO?

About half a layer down are the commercial partnerships. I thought it was far more separate than that up until the commercial crew awards. A couple of capsules to go on slightly modified existing launch systems for $6B+ and over half a decade sounds like the same thing only different. Billions for assured safety even as ISS crew transport is dependent on Russia, and Russia has acknowledged QA problems on some of its’ launch systems. Rand Simberg has covered this ground on his blog and in print. If there were a serious push for crew transport, Dragon 1 would have had taxi life support and fast rendezvous capability years ago for a fraction of the money. Boeing and Sierra Nevada could have pushed something through just months later if results rather than process oriented. I think it is sufficient to say that I find the current efforts uninspired.

Stepping a bit farther out, there are the efforts of SpaceX Blue Origin, and ULA among others for reusable orbital systems, or at least some of the components. I guess I am a bit jaded on the various hypes and want to see some gas-n-go operations before I get exited. It is basic math that a weekly turnaround vehicle of 10 ton capacity could put 500+ tons of material in orbit per year per tail number. Basic observation also is that once development is done more vehicles are relatively low cost. Knowing that one company with a handful of such vehicles could launch far more annually than than the whole world does now is also less than inspiring until I see it start happening. It will happen sooner or later, and likely from a direction I don’t expect.

The suborbital companies that I expected to lead the way don’t seem to be forging ahead at the pace I expected. Lynx on hold, Blue Origin is a question, and Space Ship Two seems like it would be better named Bransons’ Braggadocio. For suborbital research flights of RLVs, Masten seems to be the last man standing. I have posted my thoughts that suborbital companies would develop teams, vehicles, and procedures for fast turnaround that would scale into orbital systems with the same characteristics. It’s hard to see that happening right now with the possible exception of New Sheppard.

I don’t see the big idea concepts coming together even by the private players. The Mars Musk plan doesn’t seem credible or well thought out. Monster rockets don’t have a good track record for affordability, or even reliability for that matter.

Space will be developed. It will likely happen in a manner that I don’t expect. That makes my chances of making a useful contribution quite low absent pile$ of luck. So right at the moment I am a bit indifferent to the current state of play in space development, or maybe it’s just holiday blues. Either way, I’m going to try to go to Space Access next year to try to shake this lethargy

Posted in Uncategorized | 7 Comments

Random Thoughts: Throwing the Moon a Bone

[Note: This blog post was originally planned to be something significantly longer, triggered by one of Eric Berger’s recent Ars Technica articles1. But running a bootstrapped startup gave me the choice of waiting until this was totally irrelevant, or saying something less comprehensive now. I went with the latter.]

One of the space policy ideas that has been getting a lot of air-time recently, particularly with the change in presidential administrations, is that NASA should abandon its Asteroid Redirect Mission and so-called Journey to Mars for a return to the Moon instead. You would think that as someone whose website name more or less means the “lunar back country,” that I would be a huge fan of that idea. But really, I’d rather that Congress and the Trump administration stick with their Journey to Mars, and only “throw the Moon a bone.”

By throwing the Moon a bone, I mean some level of NASA involvement that is greater than benign neglect, but less than being its core focus. Why? Because when NASA picks something as a core focus, it tends to attract all of the NASA centers and their special interests and pet projects out of the woodwork, trying to find some way to be involved, even if it doesn’t make sense. But programs that aren’t core or flagship programs, that get just enough support to actually happen without becoming another “10 healthy centers” make-work project, they sometimes get real things done. I’m thinking of things like COTS, or like the competed SMD missions. So, I’d rather NASA keep its manned spaceflight program focused on an indefinite “Journey to Mars,” with NASA centers fighting over development of some big Mars mission elements like deep space habs, Mars landers, or something else like that, while keeping lunar involvement lower key.

One idea would be to do something like COTS for the Moon, as part of supporting ESA’s Lunar Village concept. Basically do a public/private partnership with 2-3 companies to develop moderate-sized (1-20mT) unmanned cargo landers to the Moon, followed by a modest CRS-like cargo delivery contract. Have that, and possibly the use of a cislunar deep space hab be our contribution to the Lunar Village. If SLS/Orion survive the axe, maybe we could also throw in providing crew transport to the Moon as well. But let ESA develop the crew lander2 and the base facilities. With the commitment of US provided logistics, and possibly crew transport to a cislunar orbital habitat, that should be encouragement enough to ESA and Russia etc to develop the rest. Ironically, that would have the US in a way playing a somewhat similar role for the Lunar Village to what Russia has been doing with Soyuz and Progress for ISS.

In return for us providing cargo deliveries, and possibly some part of the crew deliveries, NASA could ask for one of the crew landing on any given lunar mission be American (much as ESA and JAXA get to send a crew member in exchange for ATV and HTV deliveries), and having some subset of the crew time on the surface dedicated to NASA research and US commercial lunar efforts. Like ISS, they could set aside a useful fraction of the lunar cargo and crew time to be provided to commercial entities trying to prove out lunar ISRU, prospecting, propellantless launch/landing technologies, or other items related to lunar commerce. I’m just thinking about all of the technologies necessary for lunar resources to become useful to humanity–the prospecting, mining, refining, propellantless launching, etc. Imagine how much easier it would be to develop say a lunar ice mining system, if you had access to a little bit of crew support time as needed, without having to cover the full cost of getting the crew there. Without something like lunar village, the cost of having people in the loop would be prohibitive, so you’d be forced to try and do everything robotically. But the mix of robots with a tiny bit of crew time to handle the small subset of tasks that would take the vast majority of the effort to fully automate seems really promising.

My worry is that if the Moon becomes NASA’s core focus again, that NASA will insist on doing core elements in-house, like resurrecting the monstrosity previously known as LSAM to go after a manned lander. If we want to go back to the Moon in a way that doesn’t amount to little more than reheated Apollo leftovers, having the Moon be a secondary priority might actually better than being the main show.

Posted in Commercial Crew, Commercial Space, COTS, Lunar Commerce, Lunar Exploration and Development, Random Thoughts | 9 Comments

What are the Odds?

I wanted to expand on one thought from last night. If you have a launch vehicle that you want a reasonably good chance of reusing 1000x, it actually needs a lot better than a 1:1000 Loss of Vehicle probability for any given mission. With a 1 in 1000 chance of losing the vehicle on any given flight, you actually have a very high chance of losing it long before the 1000th flight. The odds of not losing a vehicle in x consecutive flights with a given reliability rating (probability of a non-LOV flight) is:

Psurvive_all = PnoLOV ^ x

Or solving for the required probability of not losing a vehicle on any given flight (assuming an equal probability on any flight):

PnoLOV = Psurvive_all^(1/x)

So, if you want a 75% chance of surviving 1000 flights in a row, you get:

PnoLOV = 0.75^.001 = .9997 or about 1 in 3500 probability of losing the vehicle on any given mission.

If you’re ok with a 50% chance of surviving 1000 flights in a row, you need more like a 1 in 1500 probability of losing the vehicle on any given flight, and if you want a 90% chance, you’re up to almost one in 10,000.

Long story short, if you want a high probability of amortizing the vehicle over 1000 flights, you’ll need to do much, much, much better than the historical best reliability levels of liquid fueled rockets (98% or so at a 95% confidence interval). This suggests that design for survivability is likely going to be just as important as design for performance or design for cost if you want a lot of flights on an airframe.

Posted in Launch Vehicles | 17 Comments