New Mars Forums

Official discussion forum of The Mars Society and

You are not logged in.


Announcement: This forum is accepting new registrations by emailing newmarsmember * become a registered member. Read the Recruiting expertise for NewMars Forum topic in Meta New Mars for other information for this process.

#1 Re: Human missions » ION Drive a fast transit to Mars » 2018-01-21 16:18:10

Fantastic! Now we just need a 50,000 kilowatt power source that doesn't weigh a ridiculous amount to power the thing. That's the problem with ion propulsion, and if I understand things right, if you double the exhaust velocity, you have to quadruple the power demand. With a few hundred kilowatts of solar power, this thing would probably take over a year to get astronauts to Mars, but when they arrive they won't have used up much fuel!

If SpaceX really can get stuff into orbit for less than $100 per kilogram, or whatever the BFR promises, there's no reason to develop ion drive. The New Horizons probe that went to Pluto passed the orbit of Mars in about a month, and it was using chemical propulsion. Chemical do that if you can launch enough of the stuff into LEO cheaply.

#2 Re: Interplanetary transportation » Zuma secret satellite; is it in orbit or a failure? » 2018-01-10 20:35:37

It does sound like there was a separation failure, but no public information is available and now there's going to be a classified Congressional Hearing.

#3 Re: Interplanetary transportation » Rockets compared » 2018-01-05 20:18:37

Probably, but I'm inclined to say "who cares?" because it'll be too expensive to use more than once or twice. The first version of SLS will put 70 tonnes in orbit and will cost something like 1 to 2 billion per launch (I don't think anyone knows). The Falcon Heavy will put 63 tonnes into orbit for 90 million and will be largely reusable, will fly in the next month, and we may see 2 or 3 more launches of it this year (unless it blows up). If Musk wanted to, Falcon Heavy could exceed the SLS. By the time SLS flies, BFR development will be well underway.

#4 Re: Interplanetary transportation » Falcon Heavy Assembly Underway » 2018-01-03 22:42:14

I was just looking at the Falcon Heavy wiki and was surprised to see that the payload to LEO is now listed as 63.8 tonnes and to Mars, 16.8 tonnes! The LEO figure is now 10% less than the SLS, which renders it even less useful and significant. If Space X wanted to, I am sure they could push it over 70 tonnes; just add a larger second stage. But of course they're turning to the BFR instead.

#5 Re: Interplanetary transportation » 2018; What lies ahead in the coming year. Your wishes and predictions. » 2017-12-28 23:23:41

There was also some talk of switching the Falcons to raptor methalox engines. I doubt that will happen now because the plan is to phase out the Falcon entirely. But it's an option that could be revived if the BFR's design changes again. I doubt the BFR will shrink further, though.

#6 Re: Interplanetary transportation » To Mars in 3 Days? » 2017-12-18 13:01:43

I doubt we have the capacity to generate that much laser light, and if we could, any mistake would fry the vehicle.

#7 Re: Human missions » Trump's Weak Space Policy Directive-1 A Big Nothingburger » 2017-12-15 20:35:54

The reference to commercial partners is important, too. The only way NASA will get to the moon and Mars in any reasonable timeline and price is through partnerships with Space X and Jeff Bezos. Musk's BFR/BFS could be landing people on the moon by 2024 and for a tenth the amount of money NASA would have to spend.

#8 Re: Human missions » Timeline milestones for a BFR Cargo landing on Mars in 2022. » 2017-12-06 11:42:52

They were test fired individually in Texas because there is no stand where all three can be fired together. The plan is to set them up on the launch pad and test fire them together later this month.

#9 Re: Human missions » Timeline milestones for a BFR Cargo landing on Mars in 2022. » 2017-12-05 11:31:09

The coupling mechanism that connects a Falcon 9 rocket to its cryogenic fuel line on the launching pad presumably already has solved the leakage problem. In his Adelaide talk, Musk said that there would be a gentle acceleration during the fuel transfer, so I guess they want to mimic the way cryogens are transferred on Earth, under gravity. You probably only need a few centimeters per second to settle fuel; in an hour that would produce an acceleration of about 10 meters per second. That's what an ullage burn does, right before the engines of a second or third stage are lit up. So that seems the easiest way to use the existing terrestrial fueling lines in orbit.

Even so, it'll require experimentation to make it work.

#10 Re: Human missions » Timeline milestones for a BFR Cargo landing on Mars in 2022. » 2017-12-03 13:20:33

It occurs to me that the Space x facility south of Waco may be too small to test a BFR. If one blows up, it could take out houses (including GW Johnson's!). I wonder whether Space X will raptor-ize the Falcon. It'd cost them a lot of money and they plan to phase out the Falcon anyway.

#11 Re: Interplanetary transportation » Falcon Heavy first flight officially in January; payload announced » 2017-12-03 12:11:15

I suppose someday in Muskville, the capital of Mars, there will be a museum with that car in it!

#12 Re: Human missions » Timeline milestones for a BFR Cargo landing on Mars in 2022. » 2017-12-03 12:05:01

I think there's more new technology here than you think, Louis. No one has ever built carbon fiber structures as large as the BFR before, let alone carbon fiber structures designed to handle cryogenics. For all we know, this may prove impractical, or at least for a multiple use vehicle (perhaps material fatigue or cracking occurs more quickly in that cryogenic and stress environment). The tanks will be self-pressurizing, and that's a new technology as well. Scaling up their experience with the Falcon to the BFR may not be as simple as we think. Then there's the biggie: orbital refueling. No one has done that before. They are still figuring that out. The 2016 presentation showed the fuel tanker docking side-to-side with the BFS; the 2017 presentation shows them docking bottom to bottom (where the engines are). That technology could take quite a while to refine. The BFS can't fly to Mars or the Moon without orbital refueling.

#13 Re: Human missions » Timeline milestones for a BFR Cargo landing on Mars in 2022. » 2017-12-03 08:54:37

Regarding cargo offloading, there's a slide in Musk's presentations that shows a crane attached to the cargo door, way up high on the BFS, lowering a box to the surface. I suspect a similar device could be used to bring people up and down as well (perhaps on a platform).

Regarding all the milestones on the timeline, Musk has a reputation of being too optimistic. We're still waiting for the Falcon Heavy; we've been waiting since 2013. If he can't get the timeline to work, what are the chances we can? Our estimates will be very rough.

#14 Re: Human missions » Omaha Shield: radiation protection systems for Unlimited Mars Career » 2017-12-02 21:08:53

I haven't heard anything about asbestos, Robert. The best way to get that question answered would be to ask an expert, perhaps at the Mars Society annual meeting. Steve Squires sometimes attends, for example. But even if the Martian fines don't have asbestos in them, they are so fine that they are regarded as potentially carcinogenic.

My impression is that the two rovers have provided a lot of ground truth for the orbital remote sensing data. As a result we can identify smectite and all sorts of other clay minerals from orbit; calcium carbonate; iron silicate minerals; in short, many of the most common Martian surface materials. But that actually reinforces GW Johnson's point about water, because many of the clays are hydrated and therefore have hydrogen in them. One can heat them up and drive off the water, but it's easier to obtain liquid water from ice, obviously.

#15 Re: Human missions » Omaha Shield: radiation protection systems for Unlimited Mars Career » 2017-12-02 12:46:33

Thanks, GW, that's the sort of bracing reminder of reality we need from time to time!

#16 Re: Human missions » Omaha Shield: radiation protection systems for Unlimited Mars Career » 2017-12-02 07:49:04

I've seen different understandings about their spectral signatures. They may be a mix of carbonaceous chondrite and Martian debris. But they are low in density and have a lot of void space. Maybe the collisions that shaped both moons caused some volatile release, and some of it froze as ice in the void space. I hope there's a lot of ice there, but it is not clear. Both moons share the inclination of Mars's axis, so there are no cryogenic cold traps at the poles.

#17 Re: Human missions » Omaha Shield: radiation protection systems for Unlimited Mars Career » 2017-12-01 23:43:28

Thank you. I suspect the articles about Deimos being ice-rich are incorrect, unfortunately. The moon's low density is more easily explained by a lot of interior void space, which suggests that both moons are rubble piles. Rubble piles are assembled through collision and collision would probably heat the material, causing loss of volatiles. I hope I am wrong about that. The spectral signatures of both moons do not fit any common asteroid type, probably because the moons are covered by material blasted off Mars, and the impact of that material would also deplete the moons of volatiles.

#18 Re: Human missions » Omaha Shield: radiation protection systems for Unlimited Mars Career » 2017-11-27 21:46:32

Could you explain "proposed tether-rail launcher at Deimos"? It sounds like it wouldn't be on the surface of the moon, but above it, presumably so it can be pointed in the right direction for launching things toward Earth. That sounds like a great way to reduce transit costs.

#19 Re: Human missions » Air locks » 2017-11-18 11:23:51

Dear Louis: Any Mars base will probably be built with pressurized tunnels connecting everything except things that have to be kept at a distance, like launch pads. Control areas will probably be in the main part of the base, not scattered about in separate, isolated pressurized structures. This is a safety issue; every pressured structure needs at least one, if not two, escape routes. I would be sure to connect pressurized units together in a complex network with lots of directions one can go in an emergency.

I would not try to "wash off" vehicles and space suits because if they have been outside any length of time they will be way below the freezing temperature and would quickly get encased in ice. I would use high pressure bursts of air. There may be ways to electrostatically charge the air slightly so dust particles are attracted off of surfaces. There may be ways to combine soft brushes with air bursts as well.

#20 Re: Interplanetary transportation » "SLS and Deep Space Gateway are certifiably toast" thanks to Space X » 2017-11-16 17:02:48

I suspect NASA eventually will have no choice to support Musk's plans. One way to save face would be to add NASA's current interest in the moon to Musk's Mars plans. In the past, the cost of doing both would be prohibitive. Now it is possible to do both economically. I wonder whether that's one reason Musk included a slide showing the BFS on the lunar surface. It's a way for him to "compromise" his plans to NASA priorities (if they ever become priorities) and acquire NASA money or equipment useful to the Mars project, which could use some of the same habitat, life support, surface transport, and scientific instrument technology as a moon project.

#21 Re: Human missions » Culture - the new frontier... » 2017-11-14 21:01:32

I wouldn't refer to a "Mars newspaper" or a "Mars radio." It would be a Mars media website with articles, podcasts, videocasts, etc.; whatever people do at that time. In my Mars novel I call it "Mars This Sol" ("this sol" = today) and it has a staff that grows as Mars's population grows.

Among the art I identified are Mars "mosaics" consisting of images laid on unused bits of land near the outpost made out of local geological materials of different colors (white salt, black basalt, gray and brown shales, silvery meteorites, etc; yellow, red, and orange sedimentary rocks are likely; copper carbonates are green). The other natural "art" would be wind-carved rocks which can take on some pretty unusual shapes. Think of them as the Martian equivalent of driftwood art. It is a habit of geologists, as they do their work, to recover such materials and unusually shaped rocks and bring them back to the outpost. The first artists are part time and they do their art around other responsibilities, but soon some permanent positions develop.

I'd add to your list music; it is very common for astronauts to be multitalented people who are often quite capable with musical instruments. As soon as Mars has a few hundred people you can be sure there will be the occasional concert, recital, skit, theatrical performance, choir, talent night, coffee house, etc. Rather than people bringing their own instruments and then taking them home, I would hope the outpost would acquire a selection. It is possible, if the atmospheric pressure of the outpost was much less than on Earth (say, 1/2 earth pressure and 40% oxygen, or 1/3 earth pressure and 60% oxygen) that music will have a different quality of sound, especially if the inert gas contains a lot of argon (which is heavier than oxygen and nitrogen, so sounds may be deeper).

I do hope there will be Martian comedians, too; they will need them!

Digital visual art would be a powerful medium and highly exportable.

When Mars gets up into the few thousand range, there might often be ethnic festivals as well focusing on ethnic foods, costumes, music, and dance.

Martian ballet; now that will be thrilling! It could acquire audiences of millions on Earth. The same with gymnastics and acrobatics.

#22 Re: Human missions » 5 Reasons Going to Mars Is Terrible Idea... » 2017-11-12 15:46:45

The key is water. If you can find a spot with plenty of water, you can run a lot of your life support mostly open cycle. And perchlorates only form in extremely dry conditions; if you add water to Martian regolith, the perchlorates break down, and one byproduct is oxygen! That's what happened with the Viking biology experiments. It should be possible to take regolith, soak it, break down the perchlorates, pour off the water (which will be full of salts), desalt the water and reuse it, or just add new water from your well. If you have huge amounts of water, you may be able to produce all the oxygen you need by wetting perchlorates.

My guess is that when humans first arrive on Mars, life support systems will cost millions of dollars per person, even with cutting corners like these. Thirty or forty years later, with a lot of experience, technological improvements, and robotic production of the systems on Mars, the price will come down to something a family can afford. That will happen sooner if the population on Mars grows faster and later if it stalls at the level of an Antarctic station.

#23 Re: Interplanetary transportation » Why Space X is the best... » 2017-11-10 16:54:50

By the way, for those who want to see the details of the 2016 Mars plan (the first one with the really big BFR) the whole thing is published here: … .29009.emu . It gives all the prices and even gives an estimate of $140,000 pr tonne of cargo to Mars. That's $140 per kilo to Mars, which means he's talking about launches of cargo to low Earth orbit that is much lower; maybe $30 per kilo!

#24 Re: Interplanetary transportation » A revival of interest in Nuclear Thermal Propulsion? » 2017-11-10 06:45:00

All that is possible. But if Space X brings about a huge cost revolution in launching stuff to low Earth orbit, it could get people to Mars in 3 months or less with chemical propulsion at a reasonable price. Space X doesn't need nuclear, IF they bring about the cost revolution they are aiming for. Nuclear could still be used with it, but it would take a long time to make up for the large up-front development cost.

#25 Re: Interplanetary transportation » Why Space X is the best... » 2017-11-02 07:57:11

It's says a lot that they put together a video of their landing failures, too. They can poke fun at themselves. It is also reminiscent of the reel of exploding rockets that a friend of Musk put together to dissuade him from going into the rocket building business.

By the way, there was a very interesting article in Ars Technica yesterday about alt-right attacks on Space X and how they appear to be attacks really on other entities and Congressmen, because Space X and Senator McCain were not involved in the legislation that is being blamed on them.

Board footer

Powered by FluxBB