[Note: After getting a few posts into this series on the “how” of alternative lunar transportation concepts, I realized that some commenters were asking about why we should even be going to the Moon, or what we’d be doing there. So even though this series focused more on the “how” of lunar transportation development, I figured a short up-front post about why we should care might be useful.
Also, I should add an up-front caveat that I’m not doing this post or series in an effort to bad-mouth other destinations such as NEOs, Mars, Venus, etc, or to propose that NASA should focus all of its money an effort on the Moon, or anything like that. I think all of those destinations are potentially interesting, and that humanity will be better-off if it can figure out how to pull all of them into its economic sphere. The point of this post and series is to explain the ways the Moon could be interesting, and to explore what technologies or approaches might enable that.]
While trying to exactly predict future markets and economic trends is often an exercise in futility, I think we can still make a broad brush-strokes “elevator pitch” for why the Moon is potentially interesting as a destination for space development. As the only pre-existing destination in space that can be accessed both quickly and frequently1, the moon is interesting for at least three or four application areas: resources, adventure, science, and possibly settlement:
- Resources: There are many resource-intensive things that can be done in space once the cost of resources in the required orbits come down far enough. These include orbital space settlements in LEO or the Lagrange points, massive communications or power-beaming platforms in high-LEO, MEO, or GEO, space tourism destinations, and all sorts of travel to destinations beyond Low Earth Orbit. If the cost of lunar-derived materials and/or manufactured goods delivered to these destinations can be competitive with Earth-launched or NEO-derived materials, then lunar mining and resource processing could be a very important reason to go to the moon.
- Adventure: In addition to raw materials, the Moon is a potentially very interesting destination in itself. Both for scientific exploration, but also for plain adventure. People visit all sorts of dangerous places on earth just for the shear thrill and beauty of it. If the cost of travel to/from the Moon can come down, the Moon is a potentially very interesting destination for adventure tourism and public or private exploration.
- Science: We’ve barely scratched the surface of understanding our nearest celestial neighbor, and on its far side there is a radio-pristine area for locating various types of observatories. Once again, If the cost of transportation to/from the Moon came down rapidly there are many international agencies and private societies who might be interested in studying the Moon and using it as a platform to explore the heavens.
- Settlement: This one has more “if’s” involved, but If it turns out that 1/6g is sufficient for long-term human health2, and If the cost of travel to/from the lunar surface can come down significantly, it very well could be a good destination for Earth’s first off-world settlements. It’s probably not as ideal as Mars or Venus, but if the other three activities are going on, and humans can adapt to the lunar environment, you will see settlement of the Moon on at least some scale.
I could probably go on, but to me those provide ample justification for being interested in going to the Moon, but as you can see, the success of all those applications depend strongly on driving down the cost of going to and returning from the Moon, both in absolute terms, and also relative to other competing alternatives such as Earth launch using RLVs and NEOs.
How to actually do that is the focus of the rest of this series.
Jonathan Goff
Latest posts by Jonathan Goff (see all)
- NASA’s Selection of the Blue Moon Lander for Artemis V - May 25, 2023
- Fill ‘er Up: New AIAA Aerospace America Article on Propellant Depots - September 2, 2022
- Independent Perspectives on Cislunar Depotization - August 26, 2022
- Trip times of days instead of months and efficient revisit periods of around a week instead of years to decades
- As I’ve pointed out many times on this blog, we really have no idea how the human body reacts to gravity levels between microgravity and 1G. We might not be able to adapt healthily to any place other than Earth or Venus, or even Ceres gravity might be enough to enable long-term settlement. The fact that we’re supposedly six decades into the space age and still don’t know how much gravity we need is nothing short of a travesty. See some of the posts in this tag for more info on how we might be able to find out: http://selenianboondocks.com/category/variable-gravity/
Mark Adler made some arguments against a far side lunar radio telescope:
http://space.stackexchange.com/questions/14866/would-a-lunar-telescope-provide-a-significant-improvement-over-terrestrial-based/14877#14877
In my opinion the most interesting lunar science would be at the cold traps. Here are a few reasons why:
1) The deeply cryogenic environment is much different from what we know on earth. I am betting we would find strange and surprising stuff on these crater floors.
2) The cold traps may have a record of the solar system’s history. A few reasons:
a) Cryogenic temperatures preserve stuff.
b) It is thought that after each lunar asteroid or comet impact that volatile gases spread across the lunar surface. Most eventually escape. But those that make their way to the cold traps freeze and stay. Thus volatile ices could accrete in layers over time. They may be layers of strata holding the solar system’s history just as the sedimentary strata here on earth have a fossil record of life on our planet.
c) There are few impacts on the cold trap floors. Like the other bodies in our solar system, asteroids tend to hug the ecliptic plane. It’s somewhat more common for an asteroid’s velocity vector wrt to earth and moon to be parallel to the ecliptic plane. Debris flux is V • n where n is surface normal vector. So there are fewer impacts on the upper lunar latitudes. Given the cold traps are surrounded by a wall, the floors receive less impacts from incoming impactors with a low flight path angle.
In my view, the lunar cold traps are the most scientifically interesting locations in the solar system. They are also of economic interest. If Spudis’ optimistic hopes are founded, they could be a source of extra terrestrial propellent that breaks the exponent in the rocket equation. Rich deposits of volatile ices could also provide life support consumables.
Hop,
I’m kind of skeptical that you’re going to get interferometric stability levels formation flying near a lagrange point without burning through a ton of propellant. And most of the issues he mentioned with the Moon are solvable:
1- It seems like thermal issues are probably solvable. We have a lot of telescopes in LEO, and they also see pretty severe thermal cycling, just at a much faster rate (every 90min). They deal with this using MLI, zero-CTE carbon fiber composite construction, heaters, and other techniques. Also, not all locations on the Moon get as extreme of temperature swings. An interferometric telescope setup in one of the two polar regions would still be pretty interesting, while not seeing as big of day night temperature swings. It’s really only radio science that has to be on the far side, and radio telescopes are less sensitive to thermal issues anyway.
2- There’s good work being done by Dr Hiroyuki Kawamoto at the University of Waseda (Tokyo) on electrostatic manipulation of lunar dust for cleaning optics, solar panels, and other sensitive locations. It turns out there are materials with similar index of refraction to glass that are conductive enough that you can make traces for electrostatically cleaning optics. I’ve seen video demonstrations and they’re pretty impressive.
3- And depending on where the telescopes are, there may be other alternatives to huge batteries for dealing with the lunar night. But I’ll get into that more later.
That said, I agree the cold traps and other features on the moon are interesting for science as well. But you’ll also notice that I put science down at #3 on my list. The Moon is scientifically interesting, but that’s not likely to be the driver for lunar development, IMO.
~Jon
I think there’s a lower limit to costs, but lunar tourism is possible. SpaceX is saying $20m per person to LEO, but they could easily get that down to $2m per if they send more at a time (a stretch Dragon on FH?) So I could see a two week moon tour costing about $5m per. At that price would there be a market?
My bias is mars because all the resources we need are already there (and would both require costly imports involving the rocket equation any place else, plus require ‘a mission’ with ‘top down command’ to get anything done.) The hardest part of a mars colony will be getting there. Living there will literally only requires gas light era technology (sure you could assume less robust modern technology but in all seriousness, the major science and tech. breakthroughs required to live on mars all happened in the 1800’s. They simply require modern application.) Einstein’s relativity missed being a product of the 1800’s by 5 years!
It often takes a long time for technology to catch up with the scientific principles that make it possible. What people are usually impressed by is nothing more than scale (or scaled up versions) when the really impressive thing is the less impressive first application that makes everything that follows possible.
If the mass of a spacecraft can be reduced to 2 tonne per person then a 50 tonne spacecraft could carry 25 people to a spacestation.
Some masses are semi-independent of the number of passengers. For instance a single docking port can be used by 1 person or 25.
Consumables will increase with the number of people but say the mass of the pumps in the life support system may increase in a sub-linear fashion.
Kennedy’s speech (May 25, 1961) to Apollo 11 (July 20, 1969) was about 8 years. The USA can probably organise a return trip within the two terms of a president. Definitely within 12 years.
–I think there’s a lower limit to costs, but lunar tourism is possible. SpaceX is saying $20m per person to LEO, but they could easily get that down to $2m per if they send more at a time (a stretch Dragon on FH?) So I could see a two week moon tour costing about $5m per. At that price would there be a market?–
Would someone rather go to the Moon as compared to ISS?
It seems one would have more tourists going to ISS if it costs 5 million rather 50 million.
Of course when it cost 5 million to go to the Moon, the cost of going to ISS [or something like it] would be less than 5 million per seat. But whether one prefer going to the Moon vs ISS would seem to depend upon the accommodations. Always in a small tin can for both destination, could make going to the Moon less desirable.
It seems that when one can go to the Moon at 5 million per seat, there will not much in terms of accommodations, but at such a low price, it seems one have build up of places to stay and things to do while on the Moon. With the Moon, once you build something, it could last for centuries, and one can build large structures. Or building material on the Moon would be cheaper than building material in LEO. One also may find caves which provide very large volumes of living area.
But before such things could happen, going to the Moon may involve adventures or travel around on the Moon. So flying in a hopper and walking around in spacesuit.
Or if seat price is 5 million, lunar rocket fuel is probably fairly cheap- so $1000 per lb or less. It seems that at any time in next century, if you are a tourist one could get someplace no one has ever gone before- if talking about some crater say less than 100 feet in diameter or top of some mountain peak, rather than no one ever been within 100 km of some spot- so an endless amount of small region never visited- and more people come and lowering the rocket fuel price the wider the radius one could travel to.
So, I mean a region might be mapped to resolution of 1 meter or better, but no person or robot has ever walked around some 1 square km area.
So just going someplace no one has gone to might have some appeal to some people, and rather merely go, one might have varying levels actual exploration. One look for a some “pretty rocks” or have something to take a picture of. Or actual professional geologist measurements type exploration. Or looking for chunk of real estate for a future lunar house- “find your spot, and we will build it for you” type thing.
Of course every lunar tourist is going bring back to earth, a small chunk of the Moon- you are not going to go to the Moon without bringing back a Moon rock [no one would fail to do that- it probably will become ritual of going to the Moon- people will do it thousands of years into the future when it doesn’t even make much sense].
Regarding formation flying and interferometric stability:
If you are talking about optical wavelengths, then yes, this seems to me impossible in space – having a solid surface to mount your telescope is something which helps A LOT.
But “radio” is much much less demanding, you can get away by recording individually and then combining the signals afterwards – you’ll “only” need to measure the distances between your spacecraft (which you could do using optical means like lasers plus atomic clocks).
(Though, I’m not an expert in these fields…)
With regards to the main topic, here (in addition to your excellent list) are IMHO advantages of “using” the Moon (in addition to going to other places), maybe a little rehashing of these points:
1. Technology proofing ground
Regardless whether the first people going to Mars will stay in Mars-orbit (or on Phobos or Deimos), or will land on Mars, there are things like habitats and ISRO-machinery that needs to be tested. And even Mars-transfer-habitats could be tested much better in in the Earth-Moon system (e.g. Lagrange or LDRO).
2. Human-biology science
OK, we *need* to find out how the human body behaves in conditions other than 0g and 1g – what better place than the Moon, where you can bring back people quickly in case things go sideways.
3. Solar-system science and Earth-Moon
While I am not qualified to judge such remarks, I heard that the samples returned by Apollo might be biased, and the existence (or rather the actual form) of the LHB is in some doubt. I forgot who or where I heard this, but the Moon is still the best place investigate this. Plus there is still the question of how exactly the Earth-Moon formation played out (how big where Proto-Earth the impactor, and so son). So I think, we are far from being done with the Moon scientifically.
4. The Moon could help
Ignoring the Moon on the way to Mars seems to me like if the first sailors going from Europe to America and back ignored Cape Verde and the Canaries – “Been there, done that – boring.”
Getting to Mars is hard, and we would do good using all the help we can get. I think the Moon can help. What you write about resources comes to my mind – not only propellant and volatiles, but also shielding for your transfer-habitat.
I have a feeling, that if we can not afford to build on the Moon a support infrastructure for space-travel, then we probably can not afford to sustain human travel from Earth to Mars. As long as we have to launch everything from Earth, humanity will be severely limited in what it can achieve with regards to Solar System exploration (and colonization). That is just my gut feeling. Maybe Elon will lower the cost of launching stuff into orbit by 3 to 4 orders of magnitude, and this will all become a mute point – but maybe Elon’s progress will be later than I like…
The cost of going to the Moon is initially going to be at least 10x that of LEO unless lunar sourced propellant is cheap.
Less than 1 ton of spacecraft/person to LEO is achievable.
Always in a small tin can for both destination, could make going to the Moon less desirable.
Which is why they will not use tuna can habitats for anything but emergency backup. That’s the advantage of all that lovely mass beneath your feet. You mentioned lunar caves/lava tubes. There really is no reason not to have massive areas to move around in. Which leads to other activities and games.
“Moon city, the retirement home that’s better than sun city!”
Digging and sealing an enclosure can be done using rovers while sitting in an office. Afterward, interior work can be done in a shirtsleeve environment. There could be no end of different tourist attractions. Pity the poor schmo that sits in an orbital tin can.
Down the road, orbital structures will catch up, but it’s not going to happen as fast as we could on the moon. Getting manpower to orbit is easier, but that’s just a fraction of what’s required to build a tourist destination.
Mars isn’t for tourists, it’s the next real world where independent development is possible unlike any place else.
Re: Science.
Given the short trip times and low light-lag (hence trivial control), the lack of lunar robotic missions strongly suggests that there’s no institutional scientific interest in the moon. Some individual scientists might be interested, of course, but it’s clearly not like Mars, Titan, Jovian moons, even Pluto.
NASA hasn’t flown a lander or rover since Apollo, and only a handful of orbiters/flybys. The ESA has flown a single orbiter in their entire history, in spite of being primarily a more science-driven space program than NASA. Only China and soon India have any interest in landers/rovers, and that seems to be more about Me-Too nation-bragging than actual scientific interest.
“Lunar science” seems to merely be a bullet-point tacked onto the justifications for human return to the moon, not something they actually believe.
It’s possible that biological materials have been boosted off Earth by large impacts (K/T impactor?) and some subsequently preserved in lunar cold traps. Radiation damage will have built up over time, but perhaps useful DNA sequences could be obtained.
For the record, I’m not saying there isn’t a reason to do science on the moon. (I’m with Hop, the potential for the lunar ice to contain a chronologically layered record of millions or even billions of years of lunar impacts is extraordinary.) But looking at the history of lunar missions, it is clearly not an actual priority of any space agency, in spite of it continually being used as a justification for manned lunar missions.
(This is especially obvious for the moon, when you consider how “dumb” a rover can be, thanks to the sub-3-second radio round trip, allowing direct remote-control driving.)
Paul,
Almost every major space country has recently, or us planning lunar scientific missions (including the US, China, India, Japan, ESA, and possibly others). The US has sent LRO, LCROSS, GRAIL, and LADEE recently, has Lunar Resource Prospector in the works, and has Lunar South Pole Aitken Basin Sample Return and at least one other lunar mission I’m forgetting on the planetary science década survey’s short list for New Frontiers missions.
I could go on, but I’m typing this on my smartphone…
Jon
For resources, I think that the low-hanging fruit is lunar polar ice for propellant and the first, best use of that is to refuel landers thereby greatly reducing the cost of access to the Moon. I believe that it is hard to make the case that the cost of developing lunar ice for propellant is the cheaper way of getting propellant for missions beyond the Moon rather than just launching it to LEO and then using SEP from there to an EML staging point.
For HSF, I think the first major ‘markets’ for companies to serve will be for an International Lunar Research Facility and international astronauts doing suborbital hops all over the Moon. One crew could go to as many locations as the entire Apollo program with just one lander refueling. That would fit within the national budgets of a lot of countries.
I think that tourism / adventure will be a modest market. Much bigger would be retirement which I think doesn’t get enough attention. Many more people would be willing to spend $500,000 +/- to move off Earth but that is a pretty expensive vacation. Retirees are the ones with the wealth to spend and their limited remaining life means that the health factors are less of an issue. As with the Sun Cities, CA & AZ, later normal settlement would build up around the retirement core. Being within real-time Skype distance of family is probably going to be a significant factor for retirees so the Moon has the advantage here over Mars.
Re: 1/6g, we could provide several hours a day with a full g in a centrifuge. The issue will come down to how many hours a day is necessary for childhood and gestational health. If it’s close to 24 hrs/day then we space advocates will all have to become O’Neilians.