Lunar X prize

Brian_B

Hi,
·I've been around this forum for long enough to know that there is some very smart people that post here . I know it would be almost impossible for a group of robot junkies to put a rover on the moon , but humor me . Would anybody be interested in at least talking about how this could be done ?


http://www.googlelunarxprize.org/

·

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Post Edited (Brian Beckius) : 11/14/2007 7:11:36 PM GMT

Tony Boersma

Nothing's impossible, especially when you're talking about something that has already been done. It'd be expensive but I think doable. The hardest part is that space is an extremely harsh environment (radiation, temperature extremes, space zombies, etc.) so conventional microcontrollers may fail immediately.

The biggest hurdle is money. I wouldn't be surprised to see Carnegie Mellon win this one again.

Are the contest organizers providing the launch vehicle? There's 40 million right there.

Tony

Whelzorn

I'd certainly throw ideas around, but like Tony said, money is a problem. I have a feeling that they don't provide a launch vehicle, given this line: "With the Google Lunar X PRIZE we hope to usher in an era of commercial exploration and development, in which small companies, groups of individuals and universities can build, launch and explore the Moon and beyond."
But if that's not the case, and they do indeed launch for you, I'd contribute as much as I felt I could. This is an important venture as far as I'm concerned, and I think it's worth the time/effort/money needed.

Tony Boersma

I'm definately for the idea. I'd lean towards a launch from Orbital Sciences Pegasus or Minotaur.
Maybe instead of talking about it here we can develop a place to talk about it off this forum, or at least once the interest has been gathered.
You can also sometimes piggyback on commercial launches, still expensive but not as bad. Also the weight is severly limited.

Since you piqued my interest I'm going to look at some preliminary numbers tonight for what it would take just to get there.

Also remember you have to land on the moon which means no parachutes.

Brian_B

It would sure be fun to try , I don't think the rover part would be that bad to build. If anybody had a delta·version "A"·rocket laying around , It would be able to escape earths gravity with 130 lbs payload (I checked ebay ,no luck).

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Post Edited (Brian Beckius) : 11/14/2007 5:18:29 AM GMT

Gadgetman

Delta 'A' rocket?

We should send a BOE with tracks...

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Brian_B

Gadgetman said...
Delta 'A' rocket?

We should send a BOE with tracks...

Delta 'A' was the the 1960's version of the delta rocket , If I was going to build a car I would start with the simplest·and most documented version·(say a model T). With modern machining and·metals you could build a car that was 100 times better than the original . The same goes for rockets ,·we already know what works and what does not. The great thing about·the USA is that all the documents are·easy to find , no use in trying to reinvent the wheel.

·I'm trying to think what would happen to the boe tracks first , melt off or shatter like·glass :-)

P.S. heres some study meterial
http://www.klabs.org/richcontent/Misc_Content/AGC_And_History/AGC_History.htm



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·"Imagination is more important than knowledge..." ·· Albert Einstein

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Post Edited (Brian Beckius) : 11/14/2007 1:38:25 PM GMT

Tony Boersma

Like I mentioned before, a Minotaur or Pegasus would be much more economical. The rocket technology is wrapped up, the contestents won't have to invent or build that.

They will have to get the rover to the moon and then land on it, that's the hard part.
The Pegasus can put 450 kg in a 200 km orbit (From the data sheet for the rocket, you can also find info on the size of a payload it can handle). Assume about 400 kg of that will be fuel, that leaves a 50 kg satellite/rover.
The Sojourner rover was 10.6 kg. The Spirit and Oppurtunity rovers were 185 kg each.

Delta rockets cost 50 to 100 million per launch, same with Ariannes. You won't find an old Delta lying around and building one doesn't make sense.




http://www.orbital.com/

Brian_B

Tony,
I was just using the delta as a example , I beleive it was the first rocket that could send a payload out of earths orbit

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·"Imagination is more important than knowledge..." ·· Albert Einstein

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Dave Hein

From what I can tell the Pegasus would cost about 15 million dollars, which is fairly inexpensive compared to other launch platforms. Once the rocket is in orbit it would need to accelarate to close to escape velocity. As it encounters the moon it would need to slow down to insert into a lunar orbit. The rocket could orbit a few times, and then execute a motor burn on the far side of the moon to cause it to land on the near side. As it approaches the surface additional motor burns would be required to bring the velocity to zero.

The amount of propellant needed can be computed from the mass ratio equation, which is

m0/m1 = exp(deltaV/Vexhaust), where
m0 is the initial mass
m1 is the final mass
deltaV is the change in velocity
Vexhaust it the exhaust speed of the rocket motor

If we use solid rocket motors with APCP propellant the exhaust speed is around 2500 m/s. This is the same propellant that is used in the Shuttle SRBs and in mid-power and high-power model rockets. The three main rocket burns would be as follows:

1. Increase from earth orbital velocity to escape velocity -- deltaV = 11.2- 8 = 3.2 km/s, m0/m1 = 3.6

2. Decrease from lunar escape velocity to lunar orbital velocity -- deltaV = 2.4 - 1.0 = 1.4 km/s, m0/m1 = 1.6

3. Decrease from lunar orbital velocity to zero - deltaV = 1.0 km/s, m0/m1 = 1.5

Combining all three burns give a mass ratio of 3.6 * 1.6 * 1.5 = 8.64

If the initial mass is 450 Kg, then the final payload mass would be 52 Kg. The total propellant mass would be about 400 Kg. This is probably about 10 times larger than the biggest amatuer rockets that have been flown.

If the payload could be reduced to 5 Kg (11 pounds) then the propellant mass could be reduced proportionately, which would get it down to the high end of amatuer rocket motors. The other major advantage is that the cost of the pegasus launch vehicle could be shared with other payloads. This may get the launch price below 2 million dollars.

Solid rocket motors are extremely simple and would be less prone to failure. However, once a solid rocket motor is lit it cannot be shut off. Also, the total energy generated by a solid rocket can vary by a few percent. Several rocket motors of various sizes would be needed to provide some degree of adjustment.

Tony Boersma

That's a pretty reasonable analysis but due to the precision involved you wouldn't want to use solid propellant. A hybrid system might work but more likely a mono or bipropellant system would be more practical.
I was also thinking that you could get close to the moon and use it's gravity to help you out. Also orbit the moon the same way it rotates which would save about 10 mph on the landing energy budget (not much but it all helps).

Brian_B

Tony & Dave,
This is all really good information; we should try to estimate how heavy the rover would be. Keep in mind it needs to have a HD transmitter , batteries , solar panels (if it’s going to live more than a short period) and video and still cameras.

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·"Imagination is more important than knowledge..." ·· Albert Einstein

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Tony Boersma

I say we put a Budweiser on it, they'd pay for it then since it'd be the first beer on the moon. Imagine the superbowl commercial where the future astronauts find a six-pack on the moon.
So that would add 12 oz.
T

Dave Hein

Tony Boersma said...
That's a pretty reasonable analysis but due to the precision involved you wouldn't want to use solid propellant. A hybrid system might work but more likely a mono or bipropellant system would be more practical.
I was also thinking that you could get close to the moon and use it's gravity to help you out. Also orbit the moon the same way it rotates which would save about 10 mph on the landing energy budget (not much but it all helps).

I made a lot of simplifying assumptions in my analysis. I assumed that we needed to leave earth's orbit at the escape velocity, and that the rocket would accelerate to the lunar escape orbit when it arrived at the moon. This is not an efficient way to do it. The efficient approach would be to go from low earth orbit to an eccentric orbit with an apogee at 240,000 miles. We would start the orbit 3 days before the moon would reach the apogee point, so that the moon would capture the rocket in it's own orbit.

I thought about using a liquid fuel rocket motor, but this is orders of magnitude more complex than a solid fuel rocket. A hybrid rocket motor is less complex, but it would still require storing a low temperature liquid oxidizer in high pressure cryogenic tanks. This is not necessary in the hybrid rockets used in model rocketry because the rocket is launched as soon as the oxidizer tank is filled.

Solid rocket motors can be made more precise by "trimming" them with smaller motors. Let's say that a motor was supposed to generate 10,000 Newton-Seconds of impulse, and it only produced 9,000 Ns. We could then fire a 1,000 Ns rocket motor to get it closer to 10,000 Ns. If the 1,000 Ns motor produced 1,100 Ns, we would fire a 100 Ns motor in the opposite direction to correct for it. By using a series of smaller motors we could get as close as needed to the desired impulse.

Whelzorn

Well I hate to be the guy who looked "Pegasus rocket" up on wikipedia, but that's exactly what I did. And they put the estimate at about $30 mil. So even if it were somewhere between $15 and 30 million, thats still an astronomical (haha...) amount for a group like us to collect.
But if it seems possible somehow, then the most important things for us to know before we can even think about designing the thing are size and weight constraints within the rocket.
I'd love to see this go somewhere, but I don't know...

Tony Boersma

I do believe that this is more of an academic excercise currently. The brainstorming is fun but I think we all know it probably won't go anywhere.
As for the solid fuel rockets, I agree with the simpler theory, but each individual rocket weighs proportionally more than a given larger rocket. We could eject the smaller motors like a pez dispenser though, that might be fun.

Brian_B

Okay,
Tony, Dave & Whelzon you guys are the rocket men, keep going on that and I’ll try to split this up into brain storm groups.


Group 2 - communications and guidance
Group 3 - descent and landing & deployment
Group 4 - inflight mechanical , rover mechanical
Group 5 - inflight electronics , rover electronics

If this ever comes to point that it looks like it could work , I'll have my buddy Max set us up a website with are own forums.

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·"Imagination is more important than knowledge..." ·· Albert Einstein

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Post Edited (Brian Beckius) : 11/15/2007 1:47:33 AM GMT

william chan

Don't try to look for the Apollo lander, the footage and pictures were faked in an earth bound studio.
Man has not walked on the moon yet.

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James Long

Tony Boersma said...
That's a pretty reasonable analysis but due to the precision involved you wouldn't want to use solid propellant. A hybrid system might work but more likely a mono or bipropellant system would be more practical.
I was also thinking that you could get close to the moon and use it's gravity to help you out. Also orbit the moon the same way it rotates which would save about 10 mph on the landing energy budget (not much but it all helps).

Tony,

I don't think either of those would work very well in the vacuum of space. The solid boosters are not designed to be lit in a vacuum, and a Hybrid (standard hybrid)·would be near to impossible to ignite.

It would be better to use some type of hypergolic propulsion (be it either hybrid or liquid). Then the ignition is not a problem. It could be throttled, shut down and restarted with little problems of ignition. Of course doing all that is much simpler said than done.

James L

Tony Boersma

I don't exactly agree with the solid rocket statement but don't have the facts to back me up.
However, the space shuttle main engine, centaur, RL10 are all restartable in space and are powered by liquid oxygen and hydrogen or kerosene. The hybrid would be an issue, but is feasable.
Like I said earlier these are preliminary brainstorming sessions. We're kind of starting with this part because you can't operate a moon rover without getting to the moon first.
Right now it's idea time.

Brian_B

william chan said...
Don't try to look for the Apollo lander, the footage and pictures were faked in an earth bound studio.
Man has not walked on the moon yet.

Ya I no, and what really suck's is that Elvis witnessed it·while he was filming "love me tender" . The·CIA hired his doctors and told them to get him hooked on drugs and slowly increase his dosage until it killed him .

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·"Imagination is more important than knowledge..." ·· Albert Einstein

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James Long

Tony Boersma said...
I don't exactly agree with the solid rocket statement but don't have the facts to back me up.
However, the space shuttle main engine, centaur, RL10 are all restartable in space and are powered by liquid oxygen and hydrogen or kerosene. The hybrid would be an issue, but is feasable.
Like I said earlier these are preliminary brainstorming sessions. We're kind of starting with this part because you can't operate a moon rover without getting to the moon first.
Right now it's idea time.

Tony,

I had an occurance once when flying high power rockets that was concluded to cause a prang (yep it came in super sonic). It was concluded afterward, the vaccum on the aft end of the rocket slowed the delay to a rate so slow that the ejection charge did not have a chance to deploy the streamer. The rocket was called the whiplash.(if you saw if fly, you would understand why). An ejection charge was used because we calculated no electronics made would survive the 38g's produced on liftoff.

The problem with igniting a solid rocket motor in space is the ability to transfer enough flame and heat (totally produced by an oxidized source) to the propellant. A black power type motor ("Estes Type') is much more likely to be lit. But has never been tested in space. A solid propellant like HTPB would require the whole interior to be filled with oxygen to provide the flame an oxidizer·source to start the grains. If you relied on the motor to produce the heat and flame transfer, the pressurization of the motor would take an extreme amount of time (resulting in a low ISP for the total burn). It would more than likely chuff, and never produce full power.

A hybrid requires a large amount of heat to start which is hard to contain within space. Also the liquid part of the motor would cause problems depending on what the liquid was. NOX would be very hard to use (requires heat for pressure). Oxygen on the other hand could be used easier (but would require some kind of pressure source.

I agree the Space Shuttle engines are relit in space for re-entry. But those engines have been tested to the extreme and cost millions. Also remember that most full size rocket engines are turbine pump fed, and are much more reliable than what we are used to dealing with.

We could probably get some thruster type motors from Aerocon (or some place similar) that have been proven to be reliable and relightable in space. But I wouldn't personally go with an untested method for a project like this. It would be too easy for the motor to fail and kill the whole project.

I think a scale version of the Aerospike (the true liquid version)·would be cool, but I haven't ever found enough information to even start drawing the design.

James L

Tony Boersma

Aerospikes are definately cool.
I see from your response that you weren't just spouting talking points.
What did Apollo use in space, nitrogen tetroxide and kerosene? I have/had (my brother stole it) book about the Saturn V called Angle of Attack. Find it, buy it, read it.
Anyway......
I like a hypergolic scheme. Dangerous for everyone, but reliable.

What about this, not rocket related.
When the rover gets to the moon the outer shell structure explodes in a geomtric fashion (like the toys that start out as a tiny ball and then blow up to a giant ball). The rover hits the surface and the outer structure (made from kevlar or graphite) is destroyed while slowing down the rover in a smaller pod. Once it all stops the rover "egg" opens up and it rights itself.

Then the mission begins................

william chan

One astronaut was asked, "What powers the air-cond in the lunar module for 72 hours non-stop on the hot lunar surface?".
He replied, "We had batteries......"

What kind of battery technology did we have in 1969 that could do what is impossible in 2007 on a mere earth surface?
All forumers here are technical geniuses. Go figure it out.

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Brian_B

William Chan,
I’ve spent thousands of hours over the years researching space travel (ask my wife). I can’t pull the numbers up as fast as some of these other guys can. Over the years I’ve established a reputation of getting all the facts first and then looking for away to make it happen. I know bankers, investors and people that can machine parts that are 10 times smaller than a human hair. When I start looking for money to make this happen, I need to look these guys in the face and be able to say “this will work”. So far I have not seen anything here yet that tells me that this won’t work. If you want to help out , go dig up some old records on the Apollo Lander and give me some concrete numbers that say it was not capable of doing the job it was designed to do.

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www.truckwiz.com

·"Imagination is more important than knowledge..." ·· Albert Einstein

http://www.diycalculator.com/subroutines.shtml· My favorite website ( Bet you can't guess why)

Dave Hein

The burn rate of APCP does depend on the ambient pressure, but I don't think it's zero in a vacuum.· I'm sure it's tougher to light APCP in a vacuum, but I would guess that it is feasible with·enough pyrogen on the igniter.· This could be easily tested on the ground in a vacuum chamber.

If it turns out that APCP doesn't light in a vacuum we could pressurize the motors and then seal them up.· It shouldn't be too hard to make a seal that will hold 14 PSI, and then burst when the motors are lit.

I was thinking that we could use a landing technique similar to the martian rovers.· Of course, mars has a weak atmosphere, which allowed the use of parachutes, but just before landing the chute was cut free and two solid rocket motors were fired to reduce the speed to close to zero.· A large balloon was inflated around the rover and it bounced a few times before coming to rest.

We wouldn't be able to use the parachute, but we could use the rocket motors and balloon method.· Given the low gravity on the moon, the rover may bounce for hours before coming to rest.

Tony Boersma

I thought of pressurizing the rocket, too. Basically each solid rocket is in an additional tube perssurized with air.
A space suit for rockets.

Wouldn't it be cool if it was air launched from the White Knight?

http://en.wikipedia.org/wiki/Spaceship_1

·

pharseid

· After the "airbag" landing on Mars a thought occurred to me. A team in Japan came up with a superelastic alloy which has unbelievable toughness. The elastic strain is comparable to rubber but the tensile strength is hundreds of times greater. With a large enough balloon of this material, might it be possible to effect a landing without using rockets to cut the landing speed?

-phar

william chan

Dear Brian,

I am not saying that the Google Lunar X-Prize project is impossible.
I am saying that sending Humans to the hot side of the Moon and staying there for 72 hours is impossible in 1969.

If you look at pictures of the lunar modules, you don't see any solar panels.
An air-conditioner that works in a vacuum on the outside is much less efficient than one that works on earth.
if such a radiative air-cond is more efficient, it would have been used widely on earth by now.

Imagine, a battery that can power a grossly inefficient aircond for 72 hours non-stop in
sunlight that is 5 times hotter than that on earth.
No reasonably sized battery can power a simple 1HP aircond on earth for 72 hours non-stop in year 2007.
The laws of thermodynamics does not allow it, even if the air-cond is made by aliens.

Humans must be the most stupid animals on earth to believe we have walked on the moon in 1969.

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Post Edited (william chan) : 11/15/2007 8:26:25 PM GMT

Tony Boersma

No, just some of us.
Yes it was the hot (lighted) side of the moon, but just like here on earth in the morning it is cooler than at noon. All of the lunar missions were planned to land in the morning. Remember the moon's day is about 14 days long.
More of the problem with the spacecraft was heating, not cooling. The spacecraft used a lot of passive measures to regulate temperature.
You are correct, there were no solar panels.
Apollo 17 was on the lunar surface for about 75 hrs compared to 21 hrs for Apollo 11. The spacecraft were not the same and the technology matured.

But back to the batteries:
Ascent Stage - Batteries: 2 x 296 Ah silver-zinc batteries
Power: 28 V DC, 115 V 400 Hz AC

Descent Stage - Batteries: 4 x 400 A·h silver-zinc batteries

I think it's crazy to think that a country can keep such a secret for so long.

And since you made this statement:
Humans must be the most stupid animals on earth to believe we have walked on the moon in 1969.
And you don't believe we did it, are you not human?

Dave Hein

william chan said...
An air-conditioner that works in a vacuum on the outside is much less efficient than one that works on earth.
if such a radiative air-cond is more efficient, it would have been used widely on earth by now.

The astronauts on the moon used a method of air-conditioning that's been around for millions of years.· It's similar to the evaporators that are used in dry climates to cool homes, like in Arizona.· Humans and other mammals use this method for cooling.· It's called sweating.· The vacuum on the moon allows going beyond evaporation, and ice can sublimate directly into vapor.· This is the method that was used on the moon.

The astronauts essentially wear what amounts to heavy winter clothing covered with an air-tight layer.· They were entirely protected from any heat entering from the outside.· They could have walked through a burning house with these suits!· The biggest problem was removing excess body heat.· This was done with a mesh of cooling tubes that transfered heat to the sublimator.