# Team Space IL and the X PRIZE

Check out this Google Lunar X PRIZE entry that uses SparkFun gear.

We have posted in the past about how we like the idea of launching various things up into the air - like this balloon, this rocket, and of course, the entire Copenhagen Suborbitals project. So naturally, this project intrigued us.

Team Space IL is a nonprofit team competing in the Google Lunar X PRIZE. They are the only group from Israel and their rocket is chock-full of SparkFun parts like an IMU, a host of sensors, and other goodies. Check out the above video for some footage from their latest test run.

If you haven't heard about it, the Google Lunar X PRIZE is a competition where teams are attempting to be the first privately funded entities to safely land a robot on the surface of the Moon and have that robot travel 500 meters over the lunar surface and send images and data back to the Earth. What's the incentive? Well, a cool \$30MM in prizes. Not too shabby! An awesome contest with some amazing entrants!

• The X-Prize sounds really cool. Though i’m not sure if this is the team to win the prize. At least, for sure it’ll be useful. I don’t understand how what they’re doing with the “green dots”, i recon they’re just surf descriptors, but what they are doing with them now is unclear. I hope they have a big bag of money backing them, otherwise, no rocket, no show.

• I think in this case MM stands for “M in plural”, M=Million, so MM=Millions, as 30 is many millions then 30MM…
Another case:
if M = 1,000,000 then MM = M2 = 1,000,0002 = 1,000,000,000,000 which is nor bad at all whichever is the meaning.
Another case:
if MM = 2,000 in roman notation, it would be 30x2,000=60,000 but I don’t see why bothering mixing notations.

• Instead of standard rocket fuel, I would focus in hydrogen, which has it’s own oxygen, and you can generate it at home, with water and electricity.

• ? Hydrogen does not have its own oxygen. Hydrogen and oxygen are two separate elements.

• You can’t get a usable mixture from electrolyzing water. Every hydrogen burning rocket engine ever built runs very rich — at least 5 to 1.
On top of that, electrolysis is dreadfully expensive. It’s easy to extract oxygen from the atmosphere (though I don’t know if that’s the standard commercial technique). Commercially, hydrogen is usually generated from hydrocarbons such as methane.
You might be interested in proposals for in-situ propellent manufacture on Mars. I can’t recall the reference, but Googling “Robert Zubrin” should get you there if nothing else works.

• \$30 Megamillions!! (sounds like a lottery)
Capital M in SI is 1,000,000. So, \$30 trillion dollars. For aerospace, maybe that’s a more appropriate figure.
Is MM really acceptable?

• Well, if that is the accounting standard, then by all means. Go wiki.answers.com. I still don’t understand where the extra M came from though.

• Either way, “MM” seems weird. :-p

• Since we’re asking random questions about space here… I’ve got one!
What is the minimum mass of rocket fuel required to lift itself into orbit? That is, if the spacecraft weighed nothing, how much fuel would it take? I’m wondering this for both solid rocket fuel, and liquid fuel. How would I go about calculating that?
Oh and then I’m wondering how much that fuel costs. Because then basically that is the minimum cost of reaching orbit using current chemical propellants and I’ve always wondered what that is. And lets say by ‘orbit’ I mean LEO.

• Trivial solution: 0
If you have zero mass, it doesn’t take any energy to move it, and thus you have enough energy.
Also, this can be trivially realized by that any amount of fuel used for a rocket can lift itself, plus some fraction of the rockets weight. (Otherwise it would never work). So any amount of suitable fuel can always lift itself orbit and then some.

• Ah, very good point, duh.
I guess I was simplifying it too much. What I am really wondering is how much fuel is required for a very small payload, ignoring the mass of the rocket. If I had a 1 lb payload, the mass of fuel quickly goes up from zero, to much more than zero.

• There are a lot of factors: mass to orbit, altitude, inclination, launch site latitude all come to mind.
You wouldn’t be far wrong assuming somewhat less than 10% payload to LEO. In the case of the Saturn V, you had somewhere around 3,000 tons of fuel and oxidizer to send 150 tons to LEO or about 50 tons to the moon. All but about 30 tons of fuel were used to get to a very low parking orbit around the Earth.
As Robert Heinlein put it, once you get to Earth orbit, you’re half way to anywhere.
Edit: corrected Saturn V throw weight

• If the rocket weighs nothing, you need to factor in the mass of the fuel.

• I know! That’s what I’m asking. What is the mass of fuel required to lift itself into space, theoretically?

• Alright, then what fuel? If you are burning paper as fuel, you will need a lot of it, if you are using liquid oxygen, you won’t need as much, and if you are using plutonium, you only need a few grams to generate enough power. So what fuel do you want?

• Ah, the old NERVA engine, eh? Even with a nuclear core for heating, you still need reaction mass.

• Well, look at my original post. I asked about solid rocket fuel. I don’t know what it’s called but I assume there is a somewhat standard solid rocket fuel being used. What do they use in the shuttle SRB’s? I also said liquid fuel, which I meant to be whatever they use normally, in, say, the Shuttle main engine, or whatever is reasonable.
Honestly, short of being pedantic, did you actually think I meant paper or plutonium? I just meant standard stuff. But I don’t know enough about it to go by name, so I had kind of hoped you guys would work with me on that.

• Looks like a job for Tsiolkovsky’s rocket equation!
delta-V = Isp * g * ln(initial mass / final mass)
It converts fuel burned to final velocity (delta-V) given the efficiency of the engine you’re using (Isp). Since you’re eliminating all other mass, the initial mass will be all fuel, and the final mass will be 0. You can find Isp numbers for various rocket engine/fuel pairings by Googling. g is the gravitational constant of 9.8m/s2. You need about 10km/s of delta-V to reach LEO. Now plug in various initial fuel masses, and see if you can get to 10km/s. (I love rocket science!)
Edit: I tried it and I don’t think it works for a situation with zero final mass, as the (initial mass / final mass) part of the equation is supposed to represent a fractional value of fuel to everything else. I’ll keep thinking on it.

• Actually, [ajn] pointed out below that in trying to simplify the problem, I oversimplified it. If the payload is zero and fuel is based on final desired weight once fuel runs out, then you can start with zero fuel and have zero mass and get anywhere you want with no energy.
So I should have asked how much fuel it takes to lift a trivially small payload to orbit. Say, 1 lb.
But it seems the final altitude needs to be factored in as well as the desired speed. I don’t see altitude in that equation?

• You need to add the mass of your load to the initial and final masses, which is TLAlexander’s weight in this case.

• .

• There are several mixes of solid rocket fuel in general use. The shuttle SRBs used a blend of ammonium perchlorate and aluminum oxide with a few other compounds as binders, catalysts and stabilizers.
As was mentioned elsewhere, kerosene and liquid hydrogen are common fuels, with liquid oxygen as an oxidizer.
Some engines use hypergolic fuels, which ignite spontaneously on contact. The most common pair I can think of is hydrazine fuel (there are various blends) and nitrogen tetroxide oxidizer. These are nasty chemicals, and the reaction products are toxic.

• The problem almost seems as if the solution will never converge! (but it does).
I don’t know what rocket fuel mixture is used in the SRB’s NASA uses (like in the shuttle or delta rockets) but that’s one possibility. The other two common rocket fuels are Kerosene/LOX (Saturn-V stage one) and Hydrogen/LOX (Saturn-V stages II and III). I don’t think any rockets NASA has ever used had a Hydrogen/LOX first stage.

• If “Z” is followed by “AA” and “AB,” then a Saturn V first stage is an “AF”

• The problem would be converting the 7.5 million lbs thrust to metric then multiplying by the burn duration (which I’d have to google for). But “AF” sounds like it’s in the right ballpark.
Wonder what the largest letter engine the Mythbusters have ever used was?

• I wonder what is the minimum amount of rocket power required to get a payload onto the moon. Tricky because you have to factor in the rocket power to achieve powered decent onto the lunar surface, and any mid-course corrections required. By going directly to Lunar decent without first achieving lunar orbit you would save some required rocket power, but there might be an advantage in leaving something in lunar orbit to relay your data back to earth.
Even with the smallest payload, I’d guess you’d still need something as large as the spaceX Falcon-9 to get to the moon, so it ain’t going to be cheap. I think just making earth orbit would be a big event for an amateur rocket team.
Here’s a question. If an “F” engine is 80 newton seconds, and each letter engine increase doubles the total impulse, what size engine would the Saturn-V first stage have been? You can go to double or triple letters if you need to go past ‘Z’.
So any rocket scientist’s out there?

• They looked at using relay satellites for the Apollo missions, but never felt the need. Keeping a satellite in lunar orbit is tricky — the gravitational field is very uneven. Relay satellites might not be worth the trouble.

• Delta-V” is the performance parameter that’s used to answer these questions. It’s the change in velocity that’s required to get from one point to another in space. For example getting from the earth’s surface to low earth orbit costs about 10km/s. It takes another 1.3km/s to get from there to lunar orbit, and another 2km/s to soft land. Your rocket needs to have the thrust capability and remaining fuel to provide these velocity changes at each phase of the mission.
There are ways to minimize the total delta-V required, and these teams are using every trick there is. As you say, direct descent saves you the trouble of going into lunar orbit, but your approach velocity will be higher, so you’ll need to burn more fuel to slow down for a soft landing. The biggest factor is making the payload mass as small as possible, which flows all the way back up the chain to the launch vehicle required (hint - if you’re flying a very small rover, you won’t need a Falcon 9).
The X-prize website has links to all the team’s sites, often with very detailed propulsion budgets. They’re doing amazing work!

• Space-X has a smaller rocket, the Falcon-1. But does it have enough delta-v to even get itself to the moon? In any event you have to design your own decent stage for your rover.

• leaving something in lunar orbit to relay your data back to earth.
You may have a problem with this setup when the “something” is on the moon’s dark side, now your rover or whatever may be closer to earth… the manned space missions only had that to recover the astronauts on the moon… notice that current unmanned terrestrial explorations (namely Spirit and Opportunity) do NOT have anything orbiting around the body, they just transmit themselves.

• This is not true at all. The rovers have always relayed their data to/from an orbiting satellite (Mars Odyssey, Mars Reconnaissance Orbiter) which then relay the data back to the Deep Space Network on Earth. The high gain antennas on these satellites are larger than the rovers themselves.

• Pathfinder, Spirit, Opportunity, and Phoenix were all capable communicating directly with the Deep Space Network. With the exception of Pathfinder, they could use orbiters as relay stations, but didn’t depend on them.

• There are plenty of spacecraft orbiting other bodies: Messenger at Mercury, LRO at the Moon, a small armada at Mars, Cassini at Saturn, and even Dawn orbiting Vesta. (Venus Express might be in orbit — I can’t remember.) Rovers are the exceptions, and they face incredibly harsh conditions. Spirit (RIP!) and Opportunity defied every rational expectation.
Edit:
There is no “dark” side of the moon, in the sense of permanently dark. There’s a near side and a far side, and they both experience night/day cycles.
(Or, from Pink Floyd: “There is no dark side of the moon, actually. As a matter of fact, it’s all dark.”)

• \$30MM
Million or… million million?

• The International System of Units sez:
M = mega = million, where
k = kilo = thousand
but what’s a “yotta”? :)

• Just million - MM or M is acceptable :).

• Ah… it’s from Roman Numerals… learned something new from a Sparkfun post - again!

• M means 1000 in roman numerals, not 1000000.

• Logic would say, if it comes from Roman numerals, that MM means 2xM = 2000, but apparently it can be used as MxM = 1,000,000.

• millimeters?

• SparkFun products were also used for early development of the Astrobotic Technology team’s GLXP systems. www.astrobotictech.com
SparkFun is certainly playing a notable part in improving the world by advancing mankind ;)

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