A lot of people (cough cough nutters cough cough) point to the terrible ratio of successful to unsuccessful Mars missions and claim that NASA (and evidently the European Space Agency, which they forget about) is covering up something.
I don’t think anything is covered up. But what’s not getting out is how hard it is to get to Mars. The problem is that Mars has planetary gravity, so touching down means lots of thrust to slow the probe, but it also has air, and just enough to make that difficult as well. NASA has actually done pretty well getting things down to the surface (when dumb engineering mistakes don’t interfere), despite the difficulty.
But as payloads increase, things get harder. And we’re now talking about landing people there. That’s not just hard; it turns out that we really aren’t sure how to do it at all.
So says Rob Manning, the Chief Engineer for the Mars Exploration Directorate, and you can read more about this fascinating topic at Universe Today, in an article written by Nancy Atkinson. It’s worth reading about current plans, future notions, and all the pains taken just to set down on the Red Planet. You may be surprised. And if you’re a conspiracy theorist, you may just learn something.
Well, probably not. But now we have someplace to link to when CTers rave about NASA and Mars.
July 18th, 2007 at 2:49 pm
Are you implying that the Beagle footage in the Transformers film wasn’t actually real?
July 18th, 2007 at 3:33 pm
If mass is a problem, why not send the supplies ahead on robotic missions? The human cargo could be put on Mars in a smaller lander.
Of course, everything would have to land fairly close together. And the cost would be higher. And all the other things I didn’t think of.
Hope I’ll still be around to see it.
July 18th, 2007 at 3:41 pm
We are here confronted with the difference between the real and the unreal. To land on Mars destroys unreality. You may expect casualties…..
Setting humans down upon the surface of Mars is monumentally harder than rising up from… (import meme of choice).
I may be a fledgling pessimist, but I will stake my reputation on this: Naturally occuring humans will never set foot on Mars in my naturally occuring lifetime.
July 18th, 2007 at 3:53 pm
On the subject of manned Mars landings, you don’t seem to have blogged about the prototype Space Activity Suit yet. They say that the limited mobility of current suit designs would be a liability in planetary gravity - in the Apollo footage, the astronauts needed to do a clever little manouvre to get up if they fell on their face, which just wouldn’t be possible in a higher gravity.
July 18th, 2007 at 4:04 pm
I don’t know that it’s landing on Mars that’s the problem. NASA and the Russian space agency have been landing on Earth for years. It’s landing on Mars and retaining an ability to leave again that’s the problem.
July 18th, 2007 at 4:05 pm
“Naturally occuring humans”….as opposed to what, Cylons? Replicants?
July 18th, 2007 at 4:09 pm
My friends and I have always ascribed the failures to the crack Martian Air Force.
The ground army is not so efficient, they haven’t even caught spirit and opportunity, yet…
July 18th, 2007 at 4:31 pm
I have an idea: Have a 2-part spaceship (kinda like the Apollo ships). Fly to Mars using the whole thing for comfortable living. Once you’re there, have the light-weight portion carry the humans so it will be easier to slow down, and have the heavy portion land separately at higher speeds (since it’s not as frail as humans). Better yet, send robotic crews ahead to setup shelters and supplies, and don’t even worry about the heavy portion of the crew ship once you’re there (although it would probably make more sense to use it for carrying more supplies).
And another idea for the actual impact: have legs attached to the spaceship with shock absorbers in them. When the ship hits the ground, the absorbers will act like the airbags on the rovers, but could be much stronger. Since there isn’t any real drag in space, you could open the legs months in advance to make sure they’re working. Of course, this would require the ship to be not moving horizontally, or it would just tip over.
Probably stupid ideas, but it’s fun to try.
July 18th, 2007 at 4:36 pm
I’m betting the first manned mission to mars won’t land. They’ll have a payload bay filled with remote-controlled vehicles to put on the planet and use, but they won’t actually touch down.
July 18th, 2007 at 6:00 pm
My favorite scenario for simplifying Mars missions was suggested by Geoffery Landis . He says it’d be easier to send folks with 40 years worth of supplies than to bring them back.
Think of it. We’d wouldn’t have to spend any engineering effort or waste fuel on return vehicles. A lander would be a lot simpler to build if it didn’t have to get back up into space again. I’m sure out of 300 million Americans and some 6 billion other folks on this planet we’d have no shortage of qualified volunteers. If the launch is in 8 or 10 years, I’d GET qualified.
July 18th, 2007 at 6:01 pm
Landis’ website:
http://www.sff.net/people/Geoffrey.Landis/index.htp
July 18th, 2007 at 6:05 pm
Landing on Mars shouldn’t be a problem.
We land Astrononauts back on Earth after sending them into space afterall.
The problem will be “getting them back”.
It’s a lot harder to get out of a gravity well, than it is to get into one.
And Mars’s gravity (.38 G) is considerably stronger than the moons.
Folcrom.
July 18th, 2007 at 6:49 pm
I don’t have the stats or citations, but I seem to recall a number of Mars missions that have failed before they have reached Mars. Well, I have Wikipedia, for what that’s worth - so Phobos 1 in 1988, Mars Observer in 1993, Mars 96 / Mars 8 in 1996, to name some. In most cases the causes of these failures are known (though it is likely these are just lies intended to hide the truth about the accuracy of the Martian planetary defense systems! But I digress.) Reading the mission profiles of these failed missions is absolutely heartbreaking.
July 18th, 2007 at 6:52 pm
Sending supplies ahead is a long standing idea for a manned Mars mission, as is sending the equipment necessary to manufacture the fuel required to take off from Mars are return home.
I’m not up on the latest regarding the practicality of those ideas, but creating supply dumps in orbit and on the surface of Mars prior to the manned mission is an eminently sensible idea, even if the costs are higher.
Would it also not be likely that the first manned mission to Mars doesn’t actually land on the surface, but is a proving mission to show that you can get there and back safely, like in the early Apollo missions? Landing on Phobos of Deimos would, of course, be a wonderful bonus.
July 18th, 2007 at 6:58 pm
It will doubtlessly be very difficult to mount a manned mission to Mars. And though i hate to admit it I too wouldn’t be surprised if it isn’t accomplished in my lifetime (and I’m only 35). I also wouldn’t be surprised if the first attempt failed tragically and spectacularly. That being said I think whatever the costs that the value of doing it is worth it.
July 18th, 2007 at 7:02 pm
“But what’s not getting out is how hard it is to get to Mars. ”
Yeah, that whole conversion between metric and Imperial is really difficult. There’s like… decimals, and fractions, and you gotta carry the one…
I should hope that anyone associated with the Mars Climate Orbiter, particularly those at Lockheed, would be too embarassed to include that project on their resume.
July 18th, 2007 at 7:22 pm
I’m sorry but human missions to Mars at this point just aren’t worth it. You’re looking at a three year trip at least with conventional rockets. You might be able to shave a bit off if you use nuclear propulsion but not that much and you have the added “fun” of getting a nuclear reactor into space. in the end your looking at a ship and payload that probably outweighs the ISS, and we haven’t even figured out how we’re going to finish building that.
I don’t think its that wrong for me to want to kick Bush in the head for diverting money from real science missions to these new manned mission programs.
July 18th, 2007 at 8:00 pm
Ed, well gutless American politicians can share some of the blame for the MCO fiasco. The USA is the only country in the world stuck with a medieval system of weights and measures, and will continue to do so until the government develops a spine and convinces the American public that converting to the metric system will not be the end of the world.
The UK was dragged kicking and screaming into the metric age when I was growing up 25-30 years ago, and now it is second nature to everyone under the age of 40. Sure we never gave up our pints of beer and milk, and miles on the road, but that’s just about it.
July 18th, 2007 at 8:35 pm
I’ve lived through the “conversion” in Canada. Some things are easier to adapt to than others. Eg, dumping Fahrenheit temp scales for Celsius has been embraced with no problems, though it took some time. Miles? Whatever. Still tend to juggle both km vs mls at times. The real problem has been in the building trades. It’s still too convenient to use inches and feet as opposed to cm and metres, mainly because there is nothing between cm and mtr and the foot is just so damn useful….for now. A 2×4, a 4×8 sheet of drywall or plywood, etc….
July 18th, 2007 at 9:45 pm
There are some of us who dont want to come back. Get me the F–ck out of here please.
July 18th, 2007 at 11:39 pm
I don’t see any reason to send humans to mars, the moon or anywhere else at this point. If it was up to me, NASA’s entire budget would be channeled into robotic exploration and space telescopes for the forseeable future. Keep developing better robots and eventually they will be able to do everything an astronaut can do, and many things better. And they don’t need life support systems or go crazy like Lisa Nowak (Hal was fictional, so he doesn’t count).
If Mars could be terraformed by robots first, then sending people later might make sense.
July 19th, 2007 at 12:00 am
Gaijin51, if NASA’s budget was even a fraction of what it should be (in terms of true advances in knowledge and experience) there would be ample room for both intensive robotic involvement in current missions as well as massive studies of how, eventually, humans as a species, might outlive our parent star.
At some point, manned space travel will no longer be optional.
July 19th, 2007 at 12:10 am
Look at the robots on Mars. they have been amazing. They last forever, they have trundled all over the place and provided great science. Yet, a few guys in an electric car could have done all that work in a week if not less. AS good as robots are, nothing beats a trained guy on the ground.
Anyway, going to Mars is cool. So.
July 19th, 2007 at 1:29 am
The problem (as far as I have understood the article from Universe Today) is that Mars has planetary gravity AND an atmosphere (which also has the added threat of dust storms and high winds in general). On the Moon there was low gravity and no atmosphere, so it was not difficult to land using thrusters. This option is out for Mars due to both atmosphere and higher gravity. On Earth we have high gravity and atmosphere, a very thick atmosphere so we can land by aerobraking and gliding. The atmosphere on Mars are just too thin for that to work (the same goes for parachutes for larger, and especially manned, missions). Airbags are nearing their weight limit as well.
So it is not a simple job to land on Mars. That said I hope they manage to do it in my lifetime.
July 19th, 2007 at 1:31 am
“The ground army is not so efficient, they haven’t even caught spirit and opportunity, yet…”
Yeah, it’s so darn hard catching those speedy little bots going 15 miles a month!
July 19th, 2007 at 1:37 am
“The atmosphere on Mars are just too thin for that to work”
So one of the problems here is that the atmosphere is thick enough to cause us trouble (e.g. extra drag when lifting off) but not thick enough to be useful (too thin for aerobraking)?
Bummer!
In the ’50s, they imagined us exploring Venus and Jupiter in person by the ’80s. And here were are, two decades later, stuck in LEO, and scratching our heads about reaching Mars.
Double bummer!
July 19th, 2007 at 1:37 am
Folcrom Says (and Paul said something similar): “Landing on Mars shouldn’t be a problem. We land Astrononauts back on Earth after sending them into space afterall.”
You didn’t read the article, did you?
July 19th, 2007 at 2:06 am
But Mark, the robots keep getting better. I bet that within 50 years they will be at least as good as “a trained guy” and in many ways better. Think of the difference in aircraft between 1903 (Wright flyer) and 1953 (jets). Robots will keep getting better by the year and by the decade.
I agree that it is “cool.” But there is no reason why it cannot wait for another century or two. The sun’s going to be OK for a few more billions of years. Why not use robots and genetically engineered lifeforms to terraform mars first? If it cannot be terraformed, then there isn’t really any practical reason to go there other than that it is “cool.” It was cool to go to the moon, too, and I’m glad we did, but it didn’t have much practical benefit.
July 19th, 2007 at 2:21 am
In addition to giving extra drag when lifting off, the atmosphere also makes it difficult to land due to high winds and the difficulty of using thrusters in an atmosphere (as seen in experiments with vtol aircrafts and landers). The exhaust creates a lot of turbulence that makes it much more difficult than if there were no atmosphere.
July 19th, 2007 at 5:30 am
Ed Minchau: Yeah, that whole conversion between metric and Imperial is really difficult. There’s like… decimals, and fractions, and you gotta carry the one…
I should hope that anyone associated with the Mars Climate Orbiter, particularly those at Lockheed, would be too embarassed to include that project on their resume.
It was more than failing to convert units properly that doomed Mars Climate Orbiter. There were problems getting the right people in at the times they were needed, operating the spacecraft outside of engineering specifications, and so on.
You can read a detailed report about it here. This was more than a simple mistake that a schoolchild should have caught; there was rotten management throughout the program. (Part of the challenge in getting to Mars is managing all the people who will make the effort happen properly.)
July 19th, 2007 at 5:42 am
The title of this entry reminds me of Kennedy’s speech, Phil:
“We choose to go to the moon and do the other things not because they are easy, but because they are hard.”
The same applies to Mars, of course.
Indeed, a Mars mission is hard, but it can be done as long as the will is there.
July 19th, 2007 at 6:33 am
Wow. Great article. And here I though Zubrin had all of this figured out. It makes perfect sense to me, though. You need some way to slow down when you get there (to zero, eventually) and you can’t use airbags, or parachutes, or thrusters, or heat shields - because the large mass of the payload and the fragile nature of human physiology.
I assume we would have to use some in-space thursters and then aerobraking with a large (probably folding) heat shield. At that point, getting the primates onto the planet is the tough part. My first thought would be to reduce the mass by breaking it up into manageable pieces, landing each of your primates individually so you could use existing methodology with the lower mass - some kind of personal lander-pod each astronaut would pilot to planetfall. Each pod could use a skycrane, parachute, thrusters, or whatever will work for the small mass. Trouble is, then you’re stuck where you land and need to rendezvous with your habitat. But once everybody is landed, you could remotely pilot the original ship down without having to worry about the humans, so you could use it to supply anybody who landed off-course in an emergency.
July 19th, 2007 at 8:51 am
It’s cool. And you know it.
July 19th, 2007 at 9:45 am
I gotta agree with those thoughts about metric. I’ve got a good deal of money invested in tools that aren’t metric, and I’m only a do-it-yourself user. I can’t imagine how much it might cost folks who make a living using non-metric tools: mechanics, carpenters, auto repair shops, etc. And to retool factories which make the tools and all the other stuff mechanized which factories use to make stuff - sheesh.
Ah, but Mars; it is our destiny to explore - everything. We’re going to Mars as a people one way or the other. But sadly, I agree with most who don’t think it’ll be in their lifetimes. I have maybe 20 years remaining on this planet (barring any untoward occurrences, of course) and I don’t think there’s any way a manned Mars mission will be accomplished in that time.
But - we WILL get there, of that I’d bet my final resting place upon.
July 19th, 2007 at 10:05 am
To the folks who think we should not waste money on human exploration and settlement in space:
The dinosaurs didn’t have a space program either.
(A paraphrase of something Larry Niven pointed out.)
July 19th, 2007 at 11:00 am
Several people have proposed sending supplies ahead early, or breaking the payload into two or more parts to get them into the range that existing technologies will work.
The MERs are 175 kg (~385 lbs) each. You can barely get one person with life support equipment in that package, and airbags aren’t a fun way to land (20 g bump). Anyway, suppose you want to land all your supplies that way. How much supplies? Like your new habitat, food, water, power stations, rovers, etc. The article says 30 metric tons is a low estimate, ~66,000 lbs (rounded down). That means 171 landers all hitting the same square kilometer, and then you have to assemble everything before you can use it. Lots of hiking and hauling and lifting and what not, and no rover to get you around because that’s in pieces, too. No tent to crawl into for a nap, that hasn’t been found and set up yet. Need a snack? How do you get it into your suit? No habitat/airlock to open the helmet.
You want to be able to land large items as single items.
Paul said:
> I don’t know that it’s landing on Mars that’s the problem. NASA and the Russian space agency have been landing on Earth for years. It’s landing on Mars and retaining an ability to leave again that’s the problem.
No, it’s landing on Mars and being able to walk away from the landing that is the problem. You could try lithobraking, but creating craters isn’t conducive to continuing your mission.
Folcrom said:
>Landing on Mars shouldn’t be a problem.
We land Astrononauts back on Earth after sending them into space afterall.
As slang said, did you read the article? There is extensive discussion about how airbags won’t work, retrothrusters won’t work, heat shields won’t work, lifting bodies won’t work, parachutes won’t work, and combinations of those systems won’t work. As was stated, there’s just enough atmosphere to make thrusters dangerous but not enough atmosphere for heat shields, parachutes, and lifting bodies to work.
You are correct about one thing - assuming the landing problem is solved, that does not address the additional challenges of the relaunch problem, which is also significantly more difficult than Apollo.
July 19th, 2007 at 11:03 am
Has anyone read the Mars trilogy by Kim Stanley Robinson? The first book is an excellent way of describing the issues in being in a hostile environment.
The Apollo mission reports are good as well to understand the many many problem sof operating on the moon. This stuff is difficult.
July 19th, 2007 at 12:14 pm
BA wrote: “A lot of people point to the terrible ratio of successful to unsuccessful Mars missions …”
Is it really terrible at all? A lot of statistics in the press that I’ve seen include the failures of the Soviet Union Mars missions. From http://seds.org/~spider/mars/mars-l.html, I count 12 successes out of 17 US missions (70%!), while there was 1 success and maybe 6 partial successes out of 20 missions for the Soviet Union and Russia going back to 1960.
So, depending on your view, you can choose either a 65% failure rate or a 70% success rate for Mars missions.
July 19th, 2007 at 12:36 pm
I am curious about several statements they made in the article. For one, they say that an airbag landing subjects the occupants to 10-20 g’s of force. What if you slow the thing down with something before you hit, and just use the airbags to cover the last bit of deceleration? Second, since when could humans not survive 10-20 g’s? People regularly survive 50-60 g’s in car accidents (though they regularly die from it too, I think that’s mostly the multi-hundred g impacts with steering wheels and such). Aircraft ejection seats create 12-20 g’s, and that’s sustained for significantly longer than just hitting the ground. The ejection seat simulators are adjustable up to 9 g’s (just for training). Typical car accidents produce longitudinal, but rearwards g’s, and ejection seats are mostly vertical, downwards g’s. Accidents are more optimal, but neither is completely optimal. If you place the crew members face-up (like in the shuttle), on springy seats with good cushioning, I don’t see any reason why they wouldn’t easily survive 20 g’s of non-sustained acceleration.
Next, why is Mach 2 the magical number for parachutes? Top fuel drag cars use parachutes in Earth atmosphere at around Mach 0.45. 4 times the speed squared is 16 times more force, but divide by 100 because of the low-density atmosphere. So Mach 2 should produce about 16% of the force that drag racing chutes are designed to handle. 100 / 16% is 6.25, and the square root is 2.5, so you should be able to go Mach 5 and deploy drag chutes without a problem. Using multi-stage chutes, you could start with lots of little chutes to bleed off large amounts of speed, then release those and deploy a couple of huge chutes for lower speeds.
Finally, a horribly inefficient, but seemingly plausible method for fuel delivery: since we need fuel to take off, then fuel to land using rockets, send a couple extra ships carrying extra fuel. On Mars orbit, dock the ships together to re-fuel the primary before landing. This would lower the weight of the landing craft by only requiring capacity for as much fuel as needed to take off or land (whichever is higher), not the amount needed to take off and land plus the amount of extra to accomodate this during takeoff. By lowering the vehicle weight, you’d make slowing down easier.
July 19th, 2007 at 2:07 pm
“Would it also not be likely that the first manned mission to Mars doesn’t actually land on the surface, but is a proving mission to show that you can get there and back safely, like in the early Apollo missions?”
Not neccessarily; the orbital mechanics don’t really like that approach. Zubrin’s book goes through the details, but I don’t have it with me so I’m going by memory. If you go for a “get there and back again” mission, you need to spend around 9 months each way, and swing by Venus for a speed boost. You then have a few days in orbit, before leaving for the return trip. If you’re going for a long-term mission, you take the direct 6-month route (no Venus fly-by), but you need to spend a year at Mars before your return window opens up. Different mission, different radiation requirements, different supply requirements–I don’t know that the fast mission would be a very good test bed for the slow one.
July 19th, 2007 at 2:50 pm
As I said in a comment I left about the Phobos article a few days ago, putting even an asperational date on a crewed Mars mission is foolhardy. The one weak link in the entire enterprise is……US! WE are the “components” that need the most protecting and have the highest maintenance requirements. We need food and water and air for the entire duration of the mission. We have to be shielded from all that pesky radiation. Our muscles turn to chicken fillets in microgravity, and at the same time our bones turn into that stuff they put inside Malteezers. (If Malteezers aren’t available over there in the USA you folks probably won’t understand that last comment, besides missing out on the greatest sweet treat ever invented by Man). We also need to be set down on the surface as gently as eggs, otherwise….scrambled eggs. And as that article in Universe Today brutally pointed out, avoiding the scrambled eggs scenario is kinda hard. And then, of course, we will insist on being able to get back to Earth in time to see the concluding episode of Lost.
Seriously, though. Landing on the Moon is rightly considered as the greatest of Mans technological achievements, and America should be forever proud of what it achieved back then. But don’t compare Apollo to a man on Mars mission. Okay, we can go on about the “if you’re in orbit you’re half-way to everywhere” philosophy, and it’s totally correct. As a purely technological exercise, getting to Mars is doable-hell it’s been done. Vikings 1 and 2, the rovers, they all show us that. But if one of those machines fail, or is broken by some outside factor, we just shrug our shoulders, find out what happened, and try again. We don’t have that luxury with a crewed machine. If one of them breaks, PEOPLE DIE. And what if one of the human “components” breaks? Do we really know enough about what happens to the human body-and indeed the human mind-when it spends three years or more off-planet?
I am not a naysayer, I am not the sort of person who, if I were alive in the middle ages, would stand at the docks and tell Colombus or Magellan or whoever that they’d fall off the edge of the world if they sail too far. I believe that the only future the human race has is to move out into space. “Man must explore.” But we have to be realistic. Going to Mars and then getting back alive is going to be a tall order, and if we rush into it, and maybe make a disasterous mistake that causes us to lose a mission, we may end up never going at all. Before we go, we’re going to need to build up a base of knowledge and experience that we’ve only begun to gather. For instance, how many of you folks out there who aren’t “in the trade” so to speak knew about the problems with landing a crew on Mars that were outlined in that Universe Today article? I sure didn’t, and to be honest I don’t think it was even considered in Zubrin’s Mars Direct work.
So like I said in my comment on the Phobos article. Le’s go to Mars, by all means. There are many problems that will have to be overcome before we do, but I believe that there are enough clever people out there to lick ‘em all. So let’s make sure that when we do go, we know exactly what we’re doing, and we’ll be doing it in a sustainable way, so that landing on Mars of itself won’t become the goal, but setting up a permanent human presence there is. After all glorious as Apollo was, that was it’s one big mistake. The American taxpayer who footed the bill saw that the Russians were beaten and so lost interest. The goal was achieved, whereas the real goal should have been to set up at least a semi-perminant presence on the Moon. I hope we don’t make that same mistake on Mars, and the only way to avoid that is to have the techology and the knowledge in place so that when we do finally go there we will survive the undertaking, and we will be going to stay.
July 19th, 2007 at 3:16 pm
“We don’t have that luxury with a crewed machine. If one of them breaks, PEOPLE DIE.”
And that is something that we are going to have to accept if we are to become a true spacefaring species. If we’re doing enough missions, then people are going to die on a regular basis, in a multitude of horrible ways. And it is going to become so commonplace that it barely merits a mention in the affected person’s hometown newspaper, next to the traffic accident reports.
July 19th, 2007 at 4:12 pm
I see your point, Ed, and I agree that death and exploration do go hand-in-hand. But with respect you’re missing my point. My point is, if we fail on a high-profile mission, such as the first Mars mission or even the second, that is hardly going to be “so commonplace that it barely merits a mention in the affected person’s hometown newspaper.” While a crewed Mars program is still in it’s infancy and maybe having to fight for funds, a disaster involving loss of life could have serious political implications.
Look at it this way. I’m sure you’ve seen on the news that awful airplane tragedy in Brazil yesterday. Now that won’t stop air travel (though admittedly it may close down that airport if that runway is at fault), and except for the unfortunate people who lost loved ones in the crash it will be largely forgotten about outside Brazil in a short while. But if that flight had been the maiden flight of a new design of aircraft, or was high-profile for some other reason, then reaction would be completely different. It wouldn’t fade from the publc conciousness so quickly. It would be the same with a failed Mars mission. When spaceflight becomes as commonplace as airflight (hmmm…I wonder…) then accidents can be “absorbed” in the same way the air travel industry “absorbes” tragedies like the one in Brazil. But if we make the mistake of going to Mars too soon and run into problems…Unlike the thousands of trips made by air every day to every part of the world, that Mars expedition would be the only show in town.
Again, I want to point out that I am not saying that we should just pull the covers over our heads and not go to Mars because we are afraid. I’m just saying that until a Mars program is so far along the road that it would be impossible to stop it, we are going to have to be very careful. And the best way to be careful in space–or in any undertaking–is to minimize the risk factor by knowing as much as possible about the dangers and difficulties we are going to face out there. “Small moves, Sparks. Small moves.”
July 19th, 2007 at 7:42 pm
Slang, Irishman
I read the article. I ignored the landing issues, as I consider all the problems of landing as “solvable”. It will eventually be attempted and achieved. Don’t make assumptions about what people have or have not read.
What concerns me more, is not the landing, but getting the Astronauts back.
Assuming the landing issues can be solved, we still have a retrieval problem.
It would be no good sending Astronauts to Mars, if having successfully landed them on the planet, we can’t get them back.
Both landing and retrieval have to be solved. Personally, I believe retrieval will be the harder of the two.
It might be better to set up bases on the Martian moons in orbit, until such problems as landing and retrieval can be solved. Something mentioned in an earlier blog as being “cool”. To me, the idea of using Martian moons as a base, would be not only cool, but also essential.
Build up infrastructure in Mars orbit first. Use Mars orbit to send down lots more robotic missions. At some point in the future, when all problems with landing and retrieval are solved, then and only then consider human landings on Mars.
Folcrom.
July 19th, 2007 at 8:54 pm
Wouldn’t robot explorers be much more flexible and useful and capable if the speed-of-light delay was a fraction of a second instead of 20 minutes?
July 19th, 2007 at 9:04 pm
For the “refueling from another ship” idea - the problem is that in negligible gravity, it is impossible to pump liquids using current technology. The only way we know how to transfer liquids between fuel tanks is by having the tanks spin to create artificial gravity to make the liquids pumpable. Nobody has demonstrated artificial gravity in space yet. Transferring liquid fuel between ships is currently impossible. Also, fuels dissipate even in enclosed containers in space, so you have to bring a huge amount of fuel with you to have enough left by the time you get there, and even more if you are going to sit around and let it dissipate while you explore. Solid or gel-based fuels would be better, but they present a whole additional suite of enormous technical challenges.
If we are going to do this (and I think we should) we need to find innovative uses of reliable, existing technology wherever possible.
July 19th, 2007 at 9:54 pm
Tiny Pieces!
July 19th, 2007 at 11:18 pm
Ships lifting off from Mars are going to need a lot of fuel.
That fuel has to get down to the surface,
before it can be used to launch a ship back into space.
Whether the Astronaut’s landing craft carries the fuel or
even if there is a fuel drop in advance,
the fuel still has to get there.
Most fuels in current use tend to be volatile.
Getting the fuel to the surface of Mars,
so it can be used to re-launch the Astronauts back into space,
is going to be really, really tricky.
Kind of like landing a rather large unstable bomb on the planets surface.
Can we make rocket fuel from the resources available on Mars?
Big unknown.
Getting the Astronauts back is going to be very hard,
even if we can get them to the surface to start with.
Anyone got a stargate?
Folcrom.
July 19th, 2007 at 11:30 pm
Corey,
It’s not strictly true that *no* technology exists for zero-g fuel transfers. After all, any restartable rocket in space effectively uses some system of pumping liquids in zero-g. That system is typically compressed inert gas, such as helium or nitrogen, to push the propellants through their conduits. This of course is only used for a brief time, just long enough to start the engine, at which the acceleration feeds the propellants.
Nevertheless, it is a system in principle. On STS-41G there was an experiment with orbital refueling in which nitrogen pressed a rocket fuel from one reservoir to another, and it was [considered to be] successful.
Another approach to consider is swapping propellant tanks. Jettison the empty one and replace it with the waiting replacement. This too will have its engineering challenges, but I think it is a plausible enough system to warrant study.
July 19th, 2007 at 11:34 pm
Buzz Parsec Says:
“Wouldn’t robot explorers be much more flexible and useful and capable if the speed-of-light delay was a fraction of a second instead of 20 minutes?”
Yes. This is an argument of the form “if p, then q”. But p is not true, so q also is not true.
July 20th, 2007 at 9:54 am
First off, nukes are the only viable energy source for long range space travel. All one then needs for fuel is some reaction mass, ie, like H2O, which we will know either exists(on Mars) or not long before we go.
Second: Why Mars now? We still don’t have space colonies, which as far as being livable are much easier to create than terraforming MArs and a LOT easier to get to,,,
I expect The Flaming Bush was just trying to leave the next president a political headache to deal with. In other words, no matter what that Pres. does,(continue the program or redirect those funds) he’s going to receive flak. It’s a no-win political situation. Good for Republicans, bad for Democrats. Just what any incompetant politico would want to leave his successor, to deflect attention from the Bush Fiasco,,,
Space Colonies now, dang it!
GAry 7
July 20th, 2007 at 9:57 am
Zippy, excellent question if we must include the Russian missions in our statistics.
MichaelS said:
> I am curious about several statements they made in the article. For one, they say that an airbag landing subjects the occupants to 10-20 g’s of force. What if you slow the thing down with something before you hit, and just use the airbags to cover the last bit of deceleration?
That’s what they already do. The MERs used a heat shield to dump orbital velocity, a parachute to slow in atmosphere, retrorockets to slow the payload, and then dropped in airbags to the ground. The people who have been doing it (i.e. Rob Manning) say that the solution does not scale up.
> Second, since when could humans not survive 10-20 g’s? … If you place the crew members face-up (like in the shuttle), on springy seats with good cushioning, I don’t see any reason why they wouldn’t easily survive 20 g’s of non-sustained acceleration.
I’d like to see some numbers on the effects of a 10 - 20 g shock load on the human body. But you seem to think the springy seats and good cushioning would help. Well, if they help, they help by reducing the shock load. But I think that is already being included in the estimate to get the shock down to 10-20 g’s.
> Next, why is Mach 2 the magical number for parachutes? Top fuel drag cars use parachutes in Earth atmosphere at around Mach 0.45. 4 times the speed squared is 16 times more force, but divide by 100 because of the low-density atmosphere. So Mach 2 should produce about 16% of the force that drag racing chutes are designed to handle. 100 / 16% is 6.25, and the square root is 2.5, so you should be able to go Mach 5 and deploy drag chutes without a problem.
Mach 1 is not an absolute velocity, but rather is relative to the air density. Mach 1 on the ground is a different velocity than Mach 1 at 30,000 ft. Also, supersonic speeds produce shock that is not a part of subsonic velocities. I think the difference in the dynamics makes extrapolating from half Mach to twice Mach a bit improper.
> Using multi-stage chutes, you could start with lots of little chutes to bleed off large amounts of speed, then release those and deploy a couple of huge chutes for lower speeds.
Except there isn’t enough atmosphere. No, not density, but altitude. You have competing needs between surface area to create drag, time to inflate the parachute, and velocity both before and after deployment. The low density of the atmosphere means the surface area must be significantly greater to get reasonable drag, but the more surface area means more inflation time, and even afterwards the velocity is higher than on Earth. The combination of parachute size vs. terminal velocity means either a chute the size of the Rose Bowl (or the equivalent in lots of chutes) to get Earth-like velocities, or a reasonable sized chute and a velocity too high to withstand the impact. Combining smaller chutes doesn’t necessarily help, as you have to deploy and keep them from tangling.
> Finally, a horribly inefficient, but seemingly plausible method for fuel delivery: since we need fuel to take off, then fuel to land using rockets, send a couple extra ships carrying extra fuel. On Mars orbit, dock the ships together to re-fuel the primary before landing. This would lower the weight of the landing craft by only requiring capacity for as much fuel as needed to take off or land (whichever is higher), not the amount needed to take off and land plus the amount of extra to accomodate this during takeoff. By lowering the vehicle weight, you’d make slowing down easier.
This is already being considered, as well as manufacturing fuel on the ground.
July 20th, 2007 at 10:13 am
Folcrom said:
> I read the article. I ignored the landing issues, as I consider all the problems of landing as “solvableâ€. It will eventually be attempted and achieved. Don’t make assumptions about what people have or have not read.
Okay, but the whole point of the article is the landing issue. The article was about why landing is not as simple as people think, and outlining the challenges of why that is so. Yet you came in and blanket dismissed the landing challenges in order to talk about return. It sounded like you weren’t paying attention, because the article was not about all the challenges or even the most severe challenge, just the unexpected challenges on the one aspect, landing.
> Assuming the landing issues can be solved, we still have a retrieval problem.
True, solving the landing problem does not address the relaunch problem. But if you can blindly dismiss the landing problem as “solvable”, then why isn’t the relaunch problem equally as easily dismissed as “solvable”? Both are technical engineering challenges that will require much effort.
> It would be no good sending Astronauts to Mars, if having successfully landed them on the planet, we can’t get them back.
While it would be a difficult political sell, several people have commented (here and elsewhere) that a one-way trip would not be a deterrent. As long as we’re talking sending supplies and equipment to keep them alive indefinitely (barring natural life span, illness, injury, etc), they’d be the first colonists.
Mark Martin said:
> Buzz Parsec: “Wouldn’t robot explorers be much more flexible and useful and capable if the speed-of-light delay was a fraction of a second instead of 20 minutes?â€
Yes. This is an argument of the form “if p, then qâ€. But p is not true, so q also is not true.
I think Buzz is saying put a human crew in orbit around Mars, and then use robotic explorers with a minimal delay.
July 20th, 2007 at 5:44 pm
Irishman says:
“I think Buzz is saying put a human crew in orbit around Mars, and then use robotic explorers with a minimal delay.”
You may be right. That makes perfect sense now that you point it out.
May 25th, 2008 at 12:15 pm
I don’t know why we think we need to go to Mars, because we wont find nothing when we get there. We have too many problems here in our oun country to think about going to Mars.
May 25th, 2008 at 12:17 pm
Yes thats it now you see what I’m talking about!