Europe goes to the moon and Mars! - Human space flight....

Ian Flint · 2004-03-11 11:58:57

John,

I suppose you mean that if launching from the Moon you can carry a lot more fuel and get to Mars a lot faster.

Again, Zubrin addresses this in "The Case for Mars". With more fuel and thus greater speed you can save a few weeks of travel time but it will be very dangerous to aerobrake into Mars orbit travelling that fast.

John Creighton · 2004-03-11 12:39:20

The point is if you have more fuell you don't need to aerobreak, or you can slow down before you aerobreak.

Lars_J · 2004-03-11 13:00:30

Robert Zubrin (in The Case for Mars) compared how much power, or Delta V, it would take to go from Earth to the Moon vs. from Earth to Mars. Just to get to the moon, it takes more power, more delta V, more fuel, more mass, and more money.

I hope you are not seriously saying that the amount of Delta-V needed for a mission is the only deciding factor for the expense of a project/mission? We are after all taking about a journey/mission that would be two orders of magnitude (100's) times longer. Factor in consumables alone, and it is clear that Mars mission would mass significatly higher. And that's only the tip of the iceberg.

BTW, I agree that going to Mars from the Moon is lunacy. But I want to go back to the Moon and to Mars as well. Doing one can gain you experience for the other, but the Moon certainly will (should) not act as a launching point - at least until we have some serious manned prescence on the Moon.

Bill White · 2004-03-11 14:11:06

BTW, I agree that going to Mars from the Moon is lunacy. But I want to go back to the Moon and to Mars as well. Doing one can gain you experience for the other, but the Moon certainly will (should) not act as a launching point - at least until we have some serious manned prescence on the Moon.

I agree. The Moon can be for practice for Mars and has some advantages of its own. Still whatever tools are used for going back to the moon should be easily transferred to a Mars mission. Design return to the moon hardware with an eye on Mars.

BTW, lunar - - > lunacy - - > lunatic. Nice choice of words.

ruski_canuk · 2004-03-11 16:07:47

Ian - I think you are missing my point completley - perhaps I conveyed it poorly. I am in 100% aggreement that if our only goal in life was to put a human presence on mars going directly from Earth to Mars would make worlds more sense than stopping at the moon. Point is that mars is a more lofty goal than the moon (even though the surface itself is safer than the moon's) and I know that I learnt how to walk before I learnt how to run. It makes sense that we use the moon, because of its close proximity, to learn scads about out of earth living. Once a tried and tested moon base already exists with a specialized short range vehicle for transportation to the Moon Base - it would make worlds of sense to launch then from that base to Mars. Just think of the little ship that remained on the Spirit / Opportunity that took the rovers the rest of the way to mars after escaping the atmosphere. The thing was tiny! IF we were launching from the moon we could specialize the craft. That is really the key of my argument - the idea of a specialized craft which is not just a flying gas can. (which the rockets initially are)

By the way I am an Engineer - so easy on your presumptions.

Ian Flint · 2004-03-11 17:22:30

Well ruski,

My idea was that we would want to get people to Mars in our lifetime. Funny me! I guess if you want to spend most of this century on the moon, then yes, it would be easier to launch from there. I bet most of the hardware would still be imported from earth, though.

Since we're talking about the distant future, isn't it interesting that basic supplies will be easier to send to the Moon than from Mars?

Oh, since you're an engineer, maybe you could answer this question for me. Which has more of an effect on the mass of a rocket? Earth's atmosphere or gravity. I always thought it was gravity. Please enlighten me...and speak like an engineer for heaven's sake; I can handle it.

ruski_canuk · 2004-03-11 17:39:09

Ian, you unfortunatly belittle yourself with your arrogant comments.

"Since we're talking about the distant future, isn't it interesting that basic supplies will be easier to send to the Moon than from Mars?"

Forgive me, this sentence doesn't make any sense. please explain

"Oh, since you're an engineer, maybe you could answer this question for me. Which has more of an effect on the mass of a rocket? Earth's atmosphere or gravity."

Depends what you mean by 'effect'. Atmosphere impedes velocity since the relative air density is much thicker than that in space where as in a gravitational field with no atmosphere huge velocities are attainable.

I think you mean that because the Moon also has gravity it will still require alot of energy. Well compared to blasting off from earth, the answer is a fraction the energy (no atmosphere and much less gravity) though if you compare the energy to that required to throw up a basketball than yes it is significant.

Bottom line is I agree with you that it takes more energy to stop first at the moon. We need to be careful that a single ambitious goal doesnt blind our vision to the whole picture. Getting to Mars will not make your life complete. Lets enjoy the ride...

RobS · 2004-03-11 19:46:51

Here are some numbers that might help answer these questions. I got most of them from an old website:

Earth's surface to low Earth orbit: 9.7 km/sec. Orbital velocity is 7.8 km/sec, so the loss from gravity and air fraction getting to orbit is 1.9 km/sec

Low Earth orbit to earth escape: 3.2 km/sec

Low Earth orbit to lunar surface: 5.5 km/sec

Lunar surface to low lunar orbit: 1.6 km/sec

Low lunar orbit to lunar escape: 0.7 km/sec

Lunar surface to escape: 2.3 km/sec

Low Earth orbit to Mars, minimum energy (Hohmann trajectory): 3.8 km/sec

Low earth orbit to Mars, six-month (Mars Direct) trajectory: 4.3 km/sec

The lowest energy way to go from the lunar surface to Mars would be to fly to the Earth (2.3 km/sec) and when flying by the Earth at a low altitude, fire your engines again; 0.6 km/sec for a Hohmann trajectory and 1.1 km/sec for six-month trajectory, so:

Lunar surface to Mars, Hohmann: 2.9 km/sec

Lunar surface to Mars, six-month trajectory: 3.4 km/sec

If you fly directly from the lunar surface to Mars without passing the Earth, add 1 or 2 km/sec (I now know how to figure it out, but don't have the time right now).

Note that low earth orbit to the lunar surface and then to Mars, Hohmann, is 3.2 (earth escape) + 2.3 (lunar landing) + 2.3 (lunar escape) + 0.6 (Hohmann supplement) = 8.4 km/sec

-- RobS

ruski_canuk · 2004-03-11 20:57:12

Rob - do you have the address of that website handy?

RobS · 2004-03-11 23:24:44

It used to be [http://www/pma.caltech.edu/~chirata/deltav.html]http://www/pma.caltech.edu/~chirata/deltav.html

But last time I went there, it was gone.

Ian Flint · 2004-03-12 10:40:22

Oops,

I guess I need to proofread a little. Here it is again: Since we're talking about the distant future, isn't it interesting that it will be easier to supply the Moon from Mars than from the Earth? (I'm talking about less delta V, of course.)

By 'effect' I mean what drives the mass of a rocket more? Gravity or air resistance?

Thanks RobS,

Look at those numbers! 5.5 km/s to get to the lunar suface compared to 3.8 km/s to get to Mars.

John Creighton · 2004-03-12 11:37:24

As has been said repeatedly we all agree that if our only goal is to go to mars then there is no point at stopping on the moon. Still, let?s stop thinking about why the moon is a hindrance to mars and let?s look at how it can be helpful if for no other reason as a pure academic exercise. The mars direct trajectory takes 6 moths and uses 4.3 km/s of delta V. How much delta V is required for 5 months, 4 months 3 months 2 months and 1 month?

If we look at the numbers again it takes 9.7 km/s of delta V to go from earth to low earth orbit yet it only takes 1.6 km/s to go from lunar orbit to low earth orbit. Clearly if we were making rockets on the moon, there would be know question that we would have much more fuel left over launching from the moon to low earth orbit then from earth. If the rockets launched from the moon docked with the rocket carrying a crew from earth, how much more delta V would we have to go from LEO to mars. Further, what if the rockets were launched from the moon with a mass driver and reached LEO by either tethers or solar tugs, then how much more delta v do we have to go from LEO to MARS. How much can this cut down on the trip time?

Don?t insult me be saying surly you don?t think it is worth building all this infrastructure to go to mars? I didn?t say it was. But if as a result of the political environment we go to the moon first and we build some of this infrastructure, how does it help us get to mars. Remember this is an academic exercise and not a practical engineering decision.

Yang Liwei Rocket · 2004-03-12 11:42:25

Theres politics there also, yes building a base on the moon is going to add more complications to such a mission like Mars but I think the USA might be thinking about political strenght, show its power in desgins, its powerful economy, its areospace, the US might want to go back to the moon before some person from Europe or Russia will go on a manned mission for construction of a lunar camp, and other ideas.

dicktice · 2004-03-12 14:41:35

My take: The U.S. won't let China get away with going to Moon without going there too. It would be unthinkable for the Americans to look up there and know that Chinese were looking down at them with impunity! They just aren't made that way--to be second best.

ruski_canuk · 2004-03-12 17:11:01

John you hit the nail on the head. Perhaps that is a clearer way of saying what I have been trying to convey. The bottom line is for many reasons (political, military, ecomonical, etc) the moon base will be built. If we conclude that such a base will exist why not use it to its fullest with making the trip to Mars easier and training people to be ready for the great risk of living on / exploring Mars.

Lets make the wisest escape.

clark · 2004-03-12 17:16:02

Suddenly, I don't feel so alone on the moon anymore.

Greetings and salutations! Nothing wrong with having your eye on the step after the next, but somewhere, sometime, we have to take the first step.

We are going to go further. How can you not support that?

RobS · 2004-03-12 17:43:56

Well, the Chinese don't want to be second best, either, and why should they be?

Regarding the delta-v figures I posted yesterday, the Mars figures were just for low earth orbit to trans-Mars injection. Midcourse corrections add another 0.1 km/sec and landing (with a heat shield, then parachutes, then engines) adds 0.7 km/sec more (according to Mars Direct).

Someone asked what was the delta-v for faster flights. Mars Direct gives these departure velocities:

250 days 3.34 km/sec
180 days 5.08 km/sec
140 days 6.93 km/sec
130 days 7.93 km/sec

NOTE departure velocity is the same as "hyberbolic excess velocity," which is the velocity a spacecraft has after leaving a planet, NOT the delta-v. The delta-v plus the orbital velocity (8 km/sec) squared is equal to the escape velocity (11.26) squared plus the departure velocity squared. Thus

(8 + 3.8) squared = 11.26 squared plus 3.34 squared = 138 (I'm rounding; I can't get the numbers to add up exactly). So:

Transit Time Delta-v from LEO
250 days 3.34 km/sec
180 days 4.35 km/sec
140 days 5.22 km/sec
130 days 5.77 km/sec

-- RobS

Yang Liwei Rocket · 2004-07-04 05:10:43

I was reading more on the Smart-1 the ESA ion engine drives seems like a very good idea

http://europa.eu.int/comm/research/head … ...en.html

SMART-1’s ion engine will be used to accelerate the probe and raise its orbit until it reaches the vicinity of the Moon, some 350,000 to 400,000 km from Earth. Then, following gravity assists from a series of lunar swingbys in late September, late October and late November 2004, SMART-1 will be “captured” by the Moon’s gravity in December 2004 and will begin using its engine to slow down and reduce the altitude of its lunar orbit.

Testing breakthrough technologies and studying the Moon
SMART-1 is not a standard outer space probe. As ESA’s first Small Mission for Advanced Research in Technology, it is primarily designed to demonstrate innovative and key technologies for future deep space science missions. However, once it has arrived at its destination, it will also perform an unprecedented scientific study of the Moon. SMART-1 is a very small spacecraft (measuring just one cubic metre). Its solar arrays, spanning 14 metres, will deliver 1.9 kW of power, about 75% of which will be used for the probe's 'solar electric' propulsion system.
In its role as technological demonstrator, SMART-1’s primary goal is to test this new solar electric propulsion system. This is a form of continuous low-thrust engine that uses electricity derived from solar panels to produce a beam of charged particles that pushes the spacecraft forward. Such engines are commonly called ion engines, and engineers consider them essential for future, long-range space missions.

http://www.innovations-report.com/html/ … ...40.html

Ion engines have weak thrust, but they can provide almost endless power and continue on very long missions for huge times. I think we should use Ion engines in future Mars missions, very important. NASA should think about this method.

Martian Republic · 2004-07-04 08:14:34

Well ruski,
My idea was that we would want to get people to Mars in our lifetime. Funny me! I guess if you want to spend most of this century on the moon, then yes, it would be easier to launch from there. I bet most of the hardware would still be imported from earth, though.
Since we're talking about the distant future, isn't it interesting that basic supplies will be easier to send to the Moon than from Mars?
Oh, since you're an engineer, maybe you could answer this question for me. Which has more of an effect on the mass of a rocket? Earth's atmosphere or gravity. I always thought it was gravity. Please enlighten me...and speak like an engineer for heaven's sake; I can handle it.

If all we want to do is do a glorified Apollo Mission to Mars, then go direct. We all agree on that. But, if you want to build a City on Mars, you would whined up going to the Moon first, because you have to build the infrastructure and develop the technology to do it and the moon is the best place to breadboard that new technology.

So it really depends on what goal are and who making the decisions of whether we go back to the Moon or go to Mars.

But, I would settle any progressive space program over the one we have right now. Just as long as we get going. We can tweak the system later for other projects, but if there going to hold it down or limit what were going to do, then you have to lower your sites whether you like or don’t like it. That was basically happened to NASA in the 1971 when Nixon started whacking NASA budgets to pieces. They had to pick a few projects that there were going to try and save and let the rest go. They had five to six generation of shuttle, fission powered, fusion powered, Lunar Basses, Mars Mission and it all got the hatchet.

Such is life.

Larry,

Martian Republic · 2004-07-04 08:33:09

Theres politics there also, yes building a base on the moon is going to add more complications to such a mission like Mars but I think the USA might be thinking about political strenght, show its power in desgins, its powerful economy, its areospace, the US might want to go back to the moon before some person from Europe or Russia will go on a manned mission for construction of a lunar camp, and other ideas.

A Lunar Base may complicate a short term trip to Mars, but it would guarantee a long tern trip some time in the not too distant future. If all there going to do is give us a Lunar Base, I would go for the biggest Lunar Base they will let us have, because you will have to develop technology build the infrastructure to support it. Most of that infrastructure can be used to support a Mars Mission that bigger Mission with faster ships and we have to put a second space station up to support the Moon colony and that too could be used to support a Mars Mission.

Larry,

Martian Republic · 2004-07-04 08:53:58

I was reading more on the Smart-1 the ESA ion engine drives seems like a very good idea
http://europa.eu.int/comm/research/head … ...en.html
SMART-1’s ion engine will be used to accelerate the probe and raise its orbit until it reaches the vicinity of the Moon, some 350,000 to 400,000 km from Earth. Then, following gravity assists from a series of lunar swingbys in late September, late October and late November 2004, SMART-1 will be “captured” by the Moon’s gravity in December 2004 and will begin using its engine to slow down and reduce the altitude of its lunar orbit.

Testing breakthrough technologies and studying the Moon
SMART-1 is not a standard outer space probe. As ESA’s first Small Mission for Advanced Research in Technology, it is primarily designed to demonstrate innovative and key technologies for future deep space science missions. However, once it has arrived at its destination, it will also perform an unprecedented scientific study of the Moon. SMART-1 is a very small spacecraft (measuring just one cubic metre). Its solar arrays, spanning 14 metres, will deliver 1.9 kW of power, about 75% of which will be used for the probe's 'solar electric' propulsion system.
In its role as technological demonstrator, SMART-1’s primary goal is to test this new solar electric propulsion system. This is a form of continuous low-thrust engine that uses electricity derived from solar panels to produce a beam of charged particles that pushes the spacecraft forward. Such engines are commonly called ion engines, and engineers consider them essential for future, long-range space missions.
http://www.innovations-report.com/html/ … ...40.html

Ion engines have weak thrust, but they can provide almost endless power and continue on very long missions for huge times. I think we should use Ion engines in future Mars missions, very important. NASA should think about this method.

It would be fine to use Ion drive on an unmanned freighter going between the Earth and Mars supplies only, but you would not want to use it as a manned craft. Because of the Ion engines weak thrust, it would take several months to get through the Van Ellen Radiation Belt that surrounds the Earth. We really need to go either fission or fusion powered Space craft for humans.

Larry,

Grypd · 2004-07-04 13:54:08

We could learn a lot from the Moon and with its "closeness" to the Earth its the perfect place to start being energy rich and it allows us to develop industries to allow constant manned prescence.
If we are thinking of the big picture you must remember. Mars Direct will not allow colonisation of Mars. It is a means to explore not to allow full scale human transportation to Mars and beyond.
If we wish to do that the moon becomes really important. An example to access the Asteroid belt the moon becomes a better "base" than earth orbit.

Timeslicer · 2004-07-05 22:45:52

Personal preference - we've been to the moon in my lifetime. I'd settle for a flags/footprints/exploration/sample-return mission to Mars at this point. Mars Direct provides that. But I don't trust NASA to do it.

Based on past NASA performance, what will happen if we go with GWB's "vision" is this:

NASA will spend a decade planning the moonbase and restoring our manned launch capabilities to where it was in 1970 (but nowhere near as safe or sensible as it could be done). Then we'll spend a decade or more building the moonbase and futzing around doing "science experiments" and "exploration" that give the impression that the moonbase is useful for something. And then we'll wake up after 25-30 years and realize that it's gotten us no closer to having infrastructure or technologies useful for getting us to Mars cheaper or faster or safer.

NASA has wasted 30 years of my life on the shuttle and ISS, in the sense that those were 30 years in which I COULD have see a moonbase established or men on Mars. I certainly don't trust that they'll make it to Mars in what remains of my lifespan. Given that politics drives their budget, maybe not even the moonbase.

I say - reward competence and punish incompetence. Shut down the shuttle. Give our share of the ISS to anyone who wants it, provided only that they'll keep it from crashing to Earth. Pay NASA to keep doing research and developing and operating space probes like the Mars rovers, at about the same rate as today. Pay for commercial launch of whatever NASA has to put into space.

The rest of what was NASA's budget should accumulate every year in a prize fund with USEFUL goals - especially goals that will have commercial value once the R&D are paid for, if only to help companies win other prizes.

That'll get us to the moon and Mars and beyond much sooner than giving the job to NASA, and it'll end up establishing technologies and infrastructure to make access to space far less costly.

Shaun Barrett · 2004-07-06 06:45:42

Hi Timeslicer!
I don't know how old you are and I'm not entirely sure your 'exploration-by-prizes' solution is necessarily the best way to go. However, I know exactly where you're coming from as regards the glacial pace of human space exploration since about 1972.
I can feel your seething frustration and it mirrors my own exactly!
:angry:

Grypd · 2004-07-06 10:07:39

Well Esa is to get bigger, both greece and luxemburg are to join.
So Esa will get a slightly bigger budget, but as it really is a cheap space organisation will it mean any big plans coming to fulfillment. Esa always tries to do space missions and research as cheap as possible it does not have Nasa's money. The smart-1 mission is example of a succesful mission, Why successful, It has shown how to use an Ion engine effectively, It is using its instruments already, its a success.

So when Smart gets to the Moon it will even if it does not find any water will still have been a worthwhile mission. But it is the big missions, people to space, landings on the moon that mean more. This is the problem with Esa it cant afford to do them. It tries to do everything with a smaller budget, it manages by having less beauracracy compared to other organisations.

So if the people of Europe where to fund Esa as well as Nasa is, it would prove to quickly become a powerful force in space. Easily being able to fund the missions to the Moon and Mars that will lead to permanent prescence in space.

But until that happens, Esa will quietly plod along, doing small missions cheaply, waiting for a chance to grow up

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Re: Europe goes to the moon and Mars! - Human space flight....

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