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Researchers led by NASA's former chief technologist are hoping to launch a satellite carrying water as the source of its fuel. The team from Cornell University, guided by Mason Peck, want their device to become the first shoebox-sized "CubeSat" to orbit the moon, while demonstrating the potential of water as a source of spacecraft fuel. It's a safe, stable substance that's relatively common even in space, but could also find greater use here on Earth as we search for alternatives to fossil fuels.
Water is a way around this issue because it is essentially an energy carrier rather than a fuel. The Cornell team isn't planning to use water itself as a propellant but to rather use electricity from solar panels to split the water into hydrogen and oxygen and use them as the fuel. The two gasses, when recombined and ignited will burn or explode, giving out the energy that they took in during the splitting process. This combustion of gasses can be used to drive the satellite forward, gaining speed or altering its position in orbit of whichever desired planet or moon is the target.
Solar panels, with high reliability and no moving parts, are ideally suited to operate in zero gravity and in the extreme environments of space, producing current from sunlight and allowing the satellite to actively engage on its mission. Traditionally this energy is stored in batteries. But the Cornell scientists want to use it to create their fuel source by splitting the on-board water.
Source: http://phys.org/news/2016-09-space-rocket-fuel-power-revolution.html
(Score: 2) by jmorris on Friday September 30 2016, @12:33AM
If they are just testing the tech, ok. If you can find a source of water up there to use as the input this makes some sense, otherwise it is pointless.
Do the math peeps. Option 1, carry hydrogen and oxygen precracked in tanks and light it up. Option 2, carry the same mass as water plus solar collectors and the equipment to crack it and then light it up.
Better still would be to use electricity to fire random mass out at super energy levels greater than just lighting it up if we can't get the crazy microwave drive working.
(Score: 2) by butthurt on Friday September 30 2016, @01:49AM
In 1807, the first wheeled vehicle with an internal combustion engine ran on hydrogen. There have been other attempts since.
https://web.archive.org/web/20080119155832/http://www.hydrogencarsnow.com/hydrogencars1807-1986.htm [archive.org]
(Score: 2) by butthurt on Friday September 30 2016, @03:08AM
Oops, I intended this to be a response to stormwyrm's comment. [soylentnews.org]
(Score: 2) by butthurt on Friday September 30 2016, @02:05AM
It's more equipment than I expected: the article says that a centrifuge separates the gasses from the water.
> Better still would be to use electricity to fire random mass out at super energy levels greater than just lighting it up [...]
Yes, ion drives are a thing.
(Score: 2) by jmorris on Friday September 30 2016, @02:28AM
Yup. Current ones use Xenon, but while a noble gas might simplify some of the design there should not be any unsolvable obstacle to firing any old mass you happen to have out the rear at very speed.
(Score: 1) by Tara Li on Friday September 30 2016, @02:51PM
Indeed. The Dawn Probe lifted off with about 425 kg of Xenon for its mission. It made two asteroid rendezvous and one orbit escape on it, plus a Mars gravity slingshot, plus other assorted orbital adjustments and maneuvering.
I'm thinking ... Musk's Interplanetary Transporter, attached to a station that makes figure-8s between Earth & Mars, using ion thrusters to build the carrier ship up to a damned good pace. Momentum bank tether stations... Seriously.
And that monster big ship Musk is talking about sending 100 people & 100 tons of cargo to Mars with? How would it do for a Lunar mission? Big, big ship - but for a 3 day trip instead of a three month one? MMmmmmm..... After the first is built, how much to build the second, or third?
(Score: 1) by khallow on Friday September 30 2016, @02:26AM
Option 1, carry hydrogen and oxygen precracked in tanks and light it up. Option 2, carry the same mass as water plus solar collectors and the equipment to crack it and then light it up.
Two things. First, consider the density of hydrogen versus the density of hydrogen in water. The densest form of pure hydrogen is liquid hydrogen which has roughly 70 kg of hydrogen per cubic meter. In comparison, water has about 110 kg of hydrogen per cubic meter. Liquid oxygen is better (1,100 kg of oxygen per cubic meter versus about 900 kg per cubic meter), but it remains that water is a denser way to store the hydrogen and oxygen you need for combustion than storing them separately. When you also add in that you don't need cryogenic storage for water, then it's a huge win in terms of the tank mass and plumbing needed to lift it to space.
(Score: 0) by Anonymous Coward on Friday September 30 2016, @07:36AM
A good point, but then you have to get the power to split the water.
(Score: 2) by Geotti on Friday September 30 2016, @04:26PM
Just carry a portable nuclear reactor with you?
(Score: 0) by Anonymous Coward on Friday September 30 2016, @02:11PM
Careful there -- tanks have considerable mass themselve. One water tank and two tiny propellant tanks, vs. two big cryo tanks, that's quite possibly a mass savings, if the tiny tanks are small enough. Electrolysis equipment adds mass, so at least initially it's almost certainly a net loss, but it's conceivable that we could refine the electrolysis gear such that it's a win for some missions.
I expect this to make the most sense on long missions with multiple Oberth maneuvers*, such as a Voyager sequel (but with extra fuel and time replacing the favorable alignment of planets). You use boosters with separate propellants to get to Earth escape; then the spacecraft proper can use sunlight to slowly convert water to propellant while coasting to the next flyby. Burn it all, repeat. Because you need a relatively small portion of the propellant at any one time, your separated propellant tanks are small; because you have months or years to fill them each time, you don't need a huge solar array. (In fact, given a PV array sized for peak power demands when active, you may already have enough spare capacity built in to produce adequate propellant while the vehicle is mostly dormant.)
*or other occasional burns, but if at least some of them aren't exploiting the Oberth effect, you're probably better off using an ion propulsion setup than a chemical rocket with any sort of fuel supply. Especially for the two most obvious such missions, exploring the asteroid belt, or a gas giant's satellites.
(Score: 0) by Anonymous Coward on Saturday October 01 2016, @09:49PM
You admonish us to do the math, but fail to do it yourself. Or if you actually have, can we see your working please?
I'm sure the folk behind this project have done theirs, and no doubt it is at least favorable enough to warrant a practical test.
(Score: 2) by jmorris on Saturday October 01 2016, @11:46PM
Should have been obvious that math wasn't really required here, simple logic would suffice. The fuel mass in both scenarios is exactly equal, one needs to keep the components cold which is actually easy in space, the other must warm water to the liquid state. The water option needs a bigger solar collector plus equipment to crack the water and a small storage for cracked fuel, making it the obviously more massive option. If the goal is to eventually harvest fuel out in space, it might be useful though. Assuming we don't build fixed cracking / fueling stations at places with ice available.