New Mars Forums

The various articles I've seen on Space.com and SpaceDaily.com have given two dates for the Chinese to go to the moon: 2010 and 2030. I suspect 2030 is more likely, as they'd have to spend an incredible amount of money to get there in 8 years. It may push NASA to return sooner, but I suspect they'll go back before 2030 anyway. Once the space station is finished in another 3 or 4 years, they will be in the position to set another goal, and the moon is the logical one. If they do that, we'd have people back on the moon by 2010 to 2015. (Of course, the new administrator does not seem to favored manned flight, so it may be that the Japanese or French will compete with the Chinese!).

I'm not sure the moon is quite as much of a panacea, though, as some think. Beaming power from the lunar surface is complicated by the day night cycle; you need at least two stations to keep the power going constantly, plus mirrors to supplement natural sunlight close to sunrise and sunset and during eclipses. You could do the same with one solar station in a very high earth orbit, inclined to the equator so that it always avoids the earth's shadow. Helium-3 is not yet known to be useful to humanity; after 50 years of trying, we are still a long way from controled fusion for power. And I hope we will develop a philosophy about the moon that regards it as more than a strip mine; even though nothing is alive there, the landscape has an inherent beauty of its own that needs some levels of respect and protection. Possibly the surface can be restored, if we ever develop the need to strip mine large areas of the moon.

                -- RobS

This information is from my planetary geology graduate student days, 1975-77, but probably is still more or less correct.

Both Vikings landed in areas where bedrock wasn't far below the surface; you can see outcrops of it. The bedrock was covered by loose rocks, gravel, sand, and dust, with scattered dust drifts. The regolith had caliche on top in spots; caliche is formed when water carries calcium carbonate, calcium sulphate, and salts to the surface and leaves them. They lightly cement the surface materials. The Viking arms had no difficulty digging through the caliche and found plenty of spots where they could dig ten centimeters (4 inches) or so.

The bedrock is extensively cracked because of cratering; the outer few hundred meters to few kilometers of Mars is considered a "megaregolith" of cracked bedrock, depending on age (the older areas are more cratered and have been "gardened" to a deeper level).

Basalt is a very tough material to tunnel through because it is so hard. Natural lava tubes can be seen in orbital photos because some parts of the roofs collapse and provide natural caves (though I once walked in a lava tube on the south side of Mt St Helens and can tell you it'd be a helluva lot of work to make one habitable because they're filled with heaps of sharp rock!). Tunnels in basalt would be full of cracks, but it would be easy to spray polyurethane on the walls to make them airtight.

               -- RobS

Here's a website with more information about lunar ice: http://www.mines.edu/research/srr/gustafsn.pdf. If you back off to "srr" you'll be at a website giving abstracts for a conference on the utilization of space resources. Lots of interesting papers. Gustafson's is a nice Powerpoint; simple and easy to follow.

For those wanting to fly around the solar system, there's a very nice chart giving the delta-vee between the Earth, moon, Mars, and Mars's moons at http://www.pma.caltech.edu/~chirata/deltav.html.

It shows, among other things, that it is easier to fly from low earth orbit to Mars orbit (using aerobraking at Mars) than to land on the moon or even to settle into a low lunar orbit. It is even easier to aerobrake into Mars orbit than put a satellite into geosynchronous orbit! From Phobos, the delta-vee to Earth is 1.9 km/sec; the delta vee from the surface of the moon to earth is 2.3 km/sec.

I did a little calculating with my calculator. If one has a source of lunar liquid oxygen/hydrogen fuel, there are many reasons to use it, among other things, to stock a "gas station" for space vehicles in a geosynchronous transfer orbit. This is an elliptical orbit with its low point 250 miles above the earth and its high point 22,300 miles above the earth. If you launch vehicles into this orbit and refuel them at the "gas station," you save about 20% or more in fuel going to Mars, because the fuel for the last 1.3 km/sec of delta-vee does not have to be hauled up from low earth orbit. If you refuel in a geosynchronous orbit, then again in low lunar orbit for a flight to the lunar surface, you cut the total fuel needed to fly cargo to the surface of the moon in half! The savings for putting a satellite in geosynchronous orbit are closer to the Mars situation; you save 25% or so in fuel used. This is a technique for improving the efficiency of chemical rockets significantly.

                     -- RobS

If a United States of Europe really does form--and in a sense its part way there now--it may be the superpower, with the United States and China close behind. We'll see. . .

But I'd like to get back to the "NASA, you have a problem" thread. I am not in the position to defend NASA--I have never worked for them, though I was a graduate student on the Viking mission many moons ago--but I do think they get a bum rap sometimes. They have available far more money for space exploration than anyone else, but they also have immense pressures from Congress and the media. Any mistakes are very costly of prestige and and threaten continued funding. As a result, they have to be super-cautious about safety issues. Furthermore, the new environment they work in involves international diplomacy and constant compromises to please dozens of foreign colleagues. The International Space Station is in an orbit that is not very useful for launching a craft to Mars because a more equatorial orbit would be unreachable from Baikonur and the other Russian launch pads.

And going to either Mars or the moon without NASA will be very difficult. The weak link in any Mars mission plan is the first few hundred kilometers: getting the craft into low earth orbit. Commercial satellite launches do not require the ability to put more than about 25 tons in low earth orbit. The Ariane 5 is about at that size, the Titan III also, the new Delta 5 (?), and the Chinese Long March rocket will be scaled to the 20-25 ton range as well. The Space Shuttle puts about 25 tons in low earth orbit as well. Twenty-five tons is enough to throw about ten tons to geosynchronous orbit, and also toward the moon (without braking at the other end) and to Mars. Right now commercial launching is driving the economics of space transportation. Everyone wants to reduce the cost of launching to low earth orbit below a few thousand bucks per kilogram (the shuttle's costs are about $8,000 per kilogram, most of the other launchers in the $9,000 to $5,000 per kilogram range). Even at $5,000 per kilogram, a Mars mission costs about $1.4 billion to get to low earth orbit (assuming an IMLEO or initial mass low earth orbit of 280 tons, which Mars Direct does). This is generally regarded as prohibitively expensive.

If launch costs come down to about $500 per kilogram to low earth orbit, however, then a Mars Direct launch--even 25 tons at a time--comes down to $140 million, a huge cost savings. It'll be ten or twenty years, however, before the launch costs drop that much (if then). If the French or the Japanese could do it, they would; if private launchers could do it, they would. The technology to do it has not yet been put in place (it may exist, but no one has put the pieces together).

If launch costs come down to $500 per kilogram by, say, 2020, I think a Mars mission becomes almost inevitable, with or without a Mars society. Every year the technology for making such a trip becomes easier to obtain; the modifications necessary to what is already known become smaller. And the launch weight will keep dropping. Werner von Braun's original proposal in the 1950s called for an IMLEO of something like 35,000 tons. Mars Direct's 280 tons might possibly halve by 2020 through better development of solar thermal rocket engines, inflatable habs, lighter nuclear reactors and rovers, more use of robotics to assemble refueling facilities on the Martian surface and moons, etc. And entrepreneurs are already looking at the ice present at the lunar poles with great interest. One could go get it for a few billion dollars now with space shuttle technology, and it will lower the cost of fueling a Mars vehicle considerably. So I think there's good reason to hope humans will walk on the moon by 2015 or so, and on Mars in the 2020s. But we'll see (if we're still alive then).

                       RobS

Space.com and Spacedaily.com have had quite a few articles about the Chinese space program. Their goals seem to be (1) manned space flight; (2) a space station; (3) a mission to the moon. I think their main motivation is simple: China is a superpower; superpowers put people in space; therefore China puts people in space. The USSR never put people on the moon. If China does, in some sense it can claim to be the new rival to the USA. Economically, in a few decades the Chinese will have the world's second largest economy (right now it is after the US, Japan, and Germany, I think). China will be the other superpower by the mid twenty-first century and they want to look the part.

                      -- RobS

For those who enjoy technical reading, the November 2001 issue of *Icarus* is now on the web--well, the abstracts, anyway--and the theme of the issue is water on Mars. The URL is http://www.idealibrary.com/links/toc/icar/154/1/0.

                       -- Robert Stockman

To follow up on two minithreads in this discussion:

1. I read somewhere about a year ago that we don't have to worry too much about the earth heating up so much that it becomes sterilized because the process occurs so slowly, we can use an asteroid and a zillion series of gravity assists to move the Earth (and Mars) into orbits more distant from the sun. As you may know, space craft get gravity assists all the time from planets, causing them to speed up or slow down, and the planet to do the opposite (much less noticably, because of the planet's enormous mass). A large asteroid--perhaps 50 miles across--could be put into an orbit that passes between the Earth, Jupiter, and Saturn periodically, stealing speed from the later two and giving it to earth through carefully crafted gravity assists. Quite clever. We'd need to move the Earth a lot, but we have a billion years to do it.

2. Regarding Martian and Earth life. Considering that thousands of tons of Mars have been blasted into space and landed on Earth, and hundreds of tons of Earth have been blasted into space and landed on Mars, over the last few billion years, for all we know, life may have originated on Mars and got transported here by a meteor impact. It is possible we are Martians and that when we visit Mars, we will find ancient, primitive cousins in some steam vent. It is also possible that life originated in Venus first, was sent to both the other two worlds by asteroidal impacts, and then was wiped out on Venus. We may never know, but finding life on Mars with substantial biochemical similarity would be indication something was transported somewhere, and Mars will have older rocks than the Earth, so it may tell us whether life originated there or not.

But we have to send people there to do this research; it'd take robots a hundred years.

                 -- RobS

Here's an article about exactly this idea from today's New York Times.

                    RobS

One Lifetime Is Not Enough for a Trip to Distant Stars
New York Times, March 5, 2002, Science Section

By NATALIE ANGIER

Nobody knows why our early ancestors decided to get off their knuckles and stand upright. Maybe they just wanted a better view of the stars.
And when sky gazers finally realized that the heavenly lights were not the footprints of the gods, but rather millions of blazing stars like our Sun writ far, they began to wonder, How do we get there? How can we leave this world and travel, not merely the 238,000 miles to the Moon, or 35 million miles to Mars, but through the vast dark silk of interstellar space, across trillions and trillions of miles, to encounter other stars, other solar systems, even other civilizations?
According to a group of scientists for whom the term "wildly optimistic dreamers" is virtually a job description, it will indeed be very difficult to travel to other stars, and nobody in either the public or private sector is about to try it any time soon. But as the researchers see it, the challenge is not insurmountable, it requires no defiance of the laws of physics, so why not have fun and start thinking about it now?
They talked about propulsion at a reasonable fraction of the speed of light, a velocity that is orders of magnitude greater than any space ship can fly today, but that would be necessary if the light-years of space between the Sun and even the nearest star are ever to be crossed.
They talked about the possibility of multigenerational space travel, and what it might be like for people who board a space ship knowing that they, their children, grandchildren and descendants through 6, 8 or 10 generations would live and die knowing nothing but life in an enclosed and entirely artificial environment, hurtling year upon year through the near-featureless expanse of interstellar space.
They talked about how big the founding crew would have to be to prevent long-term risks of inbreeding and so-called genetic drift. They talked about how the crew's chain of command would be structured, what language people would most likely speak, and what sort of marital and family policies might be put in place.
And they talked about food, all of which would have to be grown, cultivated and synthesized on board.
"One thing is almost certain," said Dr. Jean B. Hunter, an associate professor of biological and environmental engineering at Cornell. "You'll have to leave the steak, cheesecake and artichokes with hollandaise sauce behind."
Many of the subjects raised during the session were so fanciful that at times it felt like a discussion of how to clone a unicorn, and indeed half the presenters moonlight as science fiction writers.
Nevertheless, the researchers argued, human beings have shown themselves to be implacable itinerants, capable of colonizing the most hostile environments.
Dr. John H. Moore, a research professor of anthropology at the University of Florida, compared a theoretical crew of spacefaring pioneers to groups of Polynesians setting out tens of thousands of years ago in search of new islands to populate.
"Young people with food and tools would set out in large flotillas of canoes," he said. "Nobody knew if they would ever come back, the trade winds went in only one direction, and many of them perished in the ocean."
Yet over time, the Polynesians managed to colonize New Zealand, Easter Island and Hawaii.
Still, no human migration in history would compare in difficulty with reaching another star. The nearest, Alpha Centauri, is about 4.4 light- years from the Sun, and a light-year is equal to almost six trillion miles. The next nearest star, Sirius, is 8.7 light-years from home. To give a graphic sense of what these distances mean, Dr. Geoffrey A. Landis of the NASA John Glenn Research Center in Cleveland, pointed out that the fastest objects humans have ever dispatched into space are the Voyager interplanetary probes, which travel at about 9.3 miles per second.
"If a caveman had launched one of those during the last ice age, 11,000 years ago," Dr. Landis said, "it would now be only a fifth of the way toward the nearest star."
Dr. Robert L. Forward, owner and chief scientist of Forward Unlimited, a consulting company that describes itself as "specializing in exotic physics and advanced space propulsion," argued that rockets and their fuel would be so heavy that they would prevent a starship from reaching the necessary velocity to go anywhere in a sane amount of time. He envisions a rocketless spacecraft that would be manufactured in space and equipped with an ultrathin, ultralarge sail, its span as big as Texas but using no more material than a small bridge. A beam of laser light or high-energy particles from a source on Earth, in space or perhaps on the Sun- drenched planet of Mercury would be aimed at the sail, propelling it and its attached module to as much as 30 percent the speed of light - or about 55,000 miles per second.
At that pace, said Dr. Forward, a crew would reach Alpha Centauri in under 50 years.
"You could get a bunch of 16-year- olds, train them and then send them out at the age of 20," he said. "They'd have a long, boring trip, reach Alpha Centauri when they're in their 60's or 70's, do some exploring, and send everything they learned back home."
Admittedly, the astronauts would not make it home themselves. "It's a lifetime job," Dr. Forward said. "But it could be done in a single generation."
For longer journeys, designed with multigenerational crews in mind, an onboard engine and fuel source would be required, perhaps something powered by nuclear bombs, or the combining of matter and antimatter in a reaction that converts both substances into pure energy.
However the ship is propulsed, the researchers agree that it must be comfortable for long-distance travel. That means creating artificial gravity by gently rotating the craft; a spin no greater than one or two revolutions per minute would suffice.
It might also mean calling upon architects with Disney-esque sensibilities.
"The inside of one of these long- duration space habitats might feel like the inside of a shopping mall," Dr. Landis said. "Malls are carefully designed to use space efficiently, yet to give you the feeling that they're more spacious than they are."
And malls, of course, are a great place to bring the family. In Dr. Moore's view, the good old-fashioned family is the key to success in space.
"Over the past several decades, space scientists and writers of science fiction have speculated at length about the optimum size and composition" of an interstellar crew, he said. They have imagined platoons of Chuck Yeager-type stalwarts grimly enduring all hardships, or teams of bionic and vaguely asexual crew members overseeing freezers of embryos that can be defrosted and gestated as needed.
"Some of the scenarios proposed so far are downright alarming from a social science perspective," Dr. Moore said, "since they require bizarre social structures and an intensity of social relationships which are quite beyond the experience of any known human communities."
In deciding how to organize a star mission, Dr. Moore looks to the most "familiar, ubiquitous, well-ordered and well-understood" of social forms, the human family. "Virtually every human society in history has been structured along kinship lines," he said, "from small-scale foraging societies to empires comprising millions of people."
Lines of authority and seniority in a family are reasonably clear, and when they're not, well, there's always the time-out chamber.
In Dr. Moore's rendition, all recruits for an interstellar odyssey would be guaranteed the opportunity, though not the requirement, to marry and have children. Mate choice would be part of the bargain as well, with the population cannily structured so that each cohort of individuals, on reaching sexual maturity, would have about 10 potential partners of a similar age to select from.
Dr. Moore and his colleagues have developed a computer simulation called Ethnopop, in which they asked how large the crew must be in order to maintain genetic variability over time while still allowing crew members a choice of sex partners. They determined that a founding crew could be as small as 80 to 100 people and stay viable for more than a thousand years, assuming that two rules were followed: women waited until they were in their mid-30's or so before having children, and they had only a couple each. Counterintuitive though it may seem, said Dr. Moore, delayed childbearing and small families are known to help maintain genetic variability in a closed population.
Genetic diversity may be essential, but Dr. Sarah G. Thomason, a professor of linguistics at the University of Michigan, argued that the same could not be said for language. "You want everyone to be able to talk to each other as soon as they're on board," she said.
As Dr. Thomason sees it, the likeliest lingua franca for a starship will be - gracias a Dios - English. After all, she said, English is the language of the international air traffic control system, the scientific community and the educated class generally. English is the official language of 51 of the 195 nations of the world, and it is the second language of many others.
Yet, while crew members will be expected to speak English, their accents are likely to be quite diverse, and the English that their children and grandchildren end up speaking will have a rhythm and texture of its own - Space English. And though Dr. Thomason believes that the basic structure of Space English is not likely to change much from that of the mother tongue, teenagers will, of course, invent words of their own and drop words of scant use. "I can imagine the loss of words like snow, rivers, winter, mosquitoes, if they're lucky," she said.
Another arena that will test the limits of human ingenuity is space cuisine. Without livestock on board or supply ships to restock the pantry, crew members will have to be entirely self-sufficient. Dr. Hunter of Cornell envisions crops grown in hydroponic gardens, in which plants are suspended in troughs like rain gutters, and water and fertilizer are trickled slowly over their roots. Among the possible food groups are wheat, rice, sweet potatoes, beans, soy, corn, herbs and spices.
In addition, space-minded agronomists are exploring the marvels of microbes. Plants take weeks to grow, but yeastlike micro-organisms replicating in vats can be used to churn out significant quantities of carbohydrates, sugars, proteins and fats in a matter of hours. Of benefit to a community in which recycling is not just a personal virtue but a public necessity, micro-organisms can live on the carboniferous waste products of plants and people.
"There's a protein product called quorn, which is made from filamentous mold," Dr. Hunter said. "Not to make a joke of it, but it does taste like chicken."
Some clich?s, it seems, are truly universal.

Thank you for your interesting questions. Yes, a temporary dome over a construction site would be a fair amount of work to erect. Yes, 50 millibars of pressure amounts to half a tonne per square meter, so a big dome would need a big skirt and a lot of tonnes of Martian rock and soil piled on top of the skirt to keep the dome in place. Furthermore, a pressure skirt under the construction site might be hard to install, so air will leak downward into the soil and escape the bubble. So probably pressurized forms into which concrete or duricrete is poured would be better. As someone noted, a big pressure change could burst the concrete, so one would be better off keeping the pressure in the forms as close to Mars normal as possible, and depressurizing only slowly.

                           -- RobS

If you hunt around on various web sites you can find bits of additional information. Aldrin's talking about building the cyclers out of space shuttle external tanks. With two or three tanks a cycler could transport up to fifty people to Mars. The idea is to use small, light-weight "taxi" craft to go from low earth orbit to the cycler and then from the cycler to Mars at the other end. The cycler would have the housing, radiation shielding, and other heavy weight items, which would have to be boosted into space only once.

Different cycler configurations have been proposed. The basic idea seems to be based on a two year orbit around the sun, basically the free return trajectory that Mars Direct proposes (which goes to Mars in 6 months, then swings further out and returns to Earth orbit 2 years later). One cycler would pass Earth, then Mars six months later; another would pass Mars, then Earth six months later.

The problem is that one can't go to Mars every 24 months, but every 26 months. So the cycler has to return to Earth orbit every 26 months. But it returns to Earth orbit at the spot where it left, and in 26 months the Earth is now two months farther along in its orbit. This means when the cycler gets to Mars, Mars's gravity has to bend the trajectory so that the cycler returns to Earth orbit at the spot where Earth will be the next time someone wants to fly to Mars. This is called rotating the line of apsides (the line that connects perihelion and aphelion; one always encounters Earth at perihelion). Mars does not have a strong enough gravitational well to do this all the time (it can do it when the planet is at aphelion, I think, but not perihelion, or maybe vice versa). That means the cycler has to have a rocket engine on board to complete the rotation of the line of apsides. Most likely this would be an ion engine, since the cycler would have a lot of power and the cruise back to Earth, being 18-20 months, is a long cruise when the craft is unmanned.

For the cycler going in the other direction there is less of a problem. After passing the earth, the cycler returns to Mars when Mars is at the spot in its orbit for a flight to Earth, about 20 months later. That involves rotating the line of apsides, but Earth has strong enough gravity to do it.

Other possibilities: three cyclers following a more complicated path, so different ones are available for the outbound and inbound legs; and semicyclers, which stop and go into very high elliptical orbits around one planet or the other (or stop at a Lagrange point) until needed to fly in the other direction.

Designing a cycler system is made much more complicated by the fact that Mars has such an elliptical orbit. It's closest encounter to Earth every 26 months varies from 34 million to 60 million miles. That means sometimes the Cycler goes between them in something like 112 days out of the 2-year orbit and other times more like 220 days, and that means Mars is in a different position relative to Earth. If Mars had a circular orbit, the problem would be much simpler (maybe we should move it).

You can find this out by searching through Google or another engine on "interplanetary cyclers" or "semicyclers."

Very interesting ideas. I have the Scientific American here in paper copy and will look for the article, and will look at the website. I wonder whether one could build a solar cell that would make hydrogen from the UV and electricity from the IR part of the spectrum? Then you'd have both! I am not sure a catalyst could be seeded straight into the regolith, because the water is usually not sitting there as ice; it's chemically bound into the minerals, and has to be forced out of them. But maybe there are other catalysts that could do that, especially if the regolith were subjected not to ordinary sunlight, but focused intense sunlight. One could put a one hundred meter mirror in orbit around Phobos maybe two kilometers above the surface and use it to bake the regolith. Of course, the surface itself's probably the driest, because cosmic rays, micrometeoroids, solar x-rays and u.v., and other things will dry out the outer layer.

                    -- RobS

You may be right about the pressure calculation. If you are, think of my calculation as a way of figuring a maximum force we must deal with in planning a dome.

I should add that my information about available sunlight needs some correcting. While the Earth receives slightly more than twice as much sunlight per square meter as Mars, our hazy atmosphere absorbs some and our clouds reflect a lot. As a result, crops are generally relying on a total incoming sunlight not much greater than available on the surface of Mars. I have seen a figure in a space colonies book I have lying around somewhere and can post it in a few days. As a result, the use of some mirrors to reflect even more sunlight into a dome could allow some multiple levels of plant life. Maybe one could get 50% more surface area that the flat surface might suggest. That could be very helpful.

Somewhere I mentioned that biosphere 2 (you must go see it if you haven't; quite interesting) allocated 280 square meters per person for agriculture. Thus a 100 meter dome, if it has a 10 meter wide skirt for burying and thus 80 meters in diameter of open space, would have about 5,000 square meters of area and that would be able to feed about 18 people. One thing we might learn from settling Mars is what the earth's carrying capacity is.

                       -- RobS