Researchers led by NASA’s former chief technologist are hoping to launch satellite carrying water as the source of its fuel. The Cornell University team, guided by Mason Peck, wants 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.
The Present Rocket Fuel
Until we develop a warp drive or some other futuristic propulsion system, space travel is likely to rely largely on the kind of propellant-based rockets we use today. These work by firing gas out of the rear of the vehicle in a way that, thanks to the laws of Physics, pushes it forward. Such propulsion systems for satellites need to be lightweight and carry a lot of energy in a small space (high energy density) in order to continuously pack a powerful punch over the many years, or even decades, that the craft are in orbit.
Safety Issues
Safety too is of prime concern. Packing energy into a small volume and mass in the form of a fuel means even the slightest issue can have disastrous consequences, as we saw with the recent SpaceX rocket explosion. Putting satellites in orbit with any form of unstable fuel on board could spell disaster for expensive hardware or even worse, human life.
The Future of Water as Rocket Fuel
Water is a way around this safety 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.
Why Water as Source of Rocket Fuel
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. How Electrolysis Works in Space: The proposed process – known as electrolysis – involves running a current through a water sample usually containing some soluble electrolyte. This breaks down the water into oxygen and hydrogen, which are released separately at the two electrodes. On Earth, gravity would then be used to separate the gasses so they can be harvested and used. In the free-flowing zero gravity of space, however, the satellite has to use centrifugal forces from rotation to separate the gases from the solution.
Electrolysis has been use in space before to provide oxygen supplies for manned space missions without the need for high-pressure oxygen storage tanks, for example on the International Space Station. But instead of sending water into space in heavy loads on rockets, we could also one day extract it from the moon or asteroids. If the novel approach of using both the hydrogen and oxygen for satellite fuel proves successful, we could have a ready source of it waiting for us in space. This means it could shape how we power at least some of the spacecraft of the future.
Water Mining in Space
It’s a struggle to launch resources from Earth into space. You have to claw your way out of a deep gravity well. There are major advantages to using space harvested resources in space. Exploration has always made more sense if you live off the land rather than trying to bring everything with you. Space-based resources form an essential part of any significant expansion into space.
Water ice is relatively common on asteroids throughout the solar system. “Water is one of the most ubiquitous resources in the solar system,” Bonin, chief engineer of DSI said. “It can be split into oxygen and hydrogen, used as radiation shielding and now used to fuel rockets. Water is what will fuel our expansion into space. ”
Using water and other resources found in space is more economically efficient than lifting them up from Earth, which is far more energy intensive.
“You spend a lot of time, energy and money escaping Earth’s gravity, why would you want to go back?” Bonin joked. “We’ll be setting up the gas stations where people can refuel at when they move to cislunar space and beyond.”
Asteroid Mining for Resources
Companies like Deep Space Industries (DSI) are racing to enter the nascent field of asteroid mining, and the capability to refuel on asteroid water without returning to Earth could prove to be a game-changer for the industry. Water would be relatively easy to harvest from asteroids, so DSI plans to launch a small probe called Prospector-1 into space with an attached water rocket sometime next year.
“Our rockets basically take water, bring it up to a very high temperature, and then expel it to produce thrust. It’s a flying steam kettle,” Grant Bonin, chief engineer of DSI, told The Daily Caller News Foundation. “This is fundamentally a much simpler and more robust system than other proposals to use water as rocket fuel, which require the hydrogen and oxygen generated to be refrigerated to be stored.”
DSI’s probe will rendezvous with a near-Earth asteroid in 2020 to assess its value for mineral mining. It will use a new water propulsion system that ejects super-heated water vapor to generate thrust. DSI intends to mine water from asteroids to provide future spacecraft with the ability to refuel in space.
DSI intends to sell air, building material, water and propellant to other companies in space at a cheaper price than launching them from Earth. DSI plans to follow up its survey with the first commercial space mining mission, which will likely mine water from the asteroids to fuel the return trip.
DSI and a recent wave of other private companies such as SpaceX, Blue Origin, and Bigelow Aerospace have been encouraged by a rapidly changing legal environment.
The Law of the Land
The U.S. Senate unanimously passed a bill in November, later signed by President Barack Obama that legalized asteroid mining and granted property rights in space to private companies. Under the new law, companies own the resources they extract from asteroids, such as platinum and water. Experts at think tanks routinely noted the lack of legal recognition of property rights in space as one of the major road blocks to the development of space-based industries.
Previously, the international Outer Space Treaty declared that no nation could own property in space. The wording of the treaty is vague enough that companies want to ensure that they will own the resources they mine from asteroids before investing. The bill Congress passed would make those property rights official, at least under U.S. law.
Another private space company called Planetary Resources has already launched a simple test vehicle into low Earth orbit and also intends to mine asteroids.
From Satellites to Cars of the Future
As is often the case, developments in space technology are pushing concepts that have the potential to help overcome significant energy problems here on Earth. Electricity is really difficult to store and, as we increase our renewable energy supplies, we need to buffer the supply and demand. Wind and solar farms are really inefficient forms of renewable energy, not because of problems with the generating technology but because we often cannot do anything useful with the energy that they produce. The electricity grid struggles at times of high production and low energy need… and need for storage technology becomes very critical impacting overall efficiency.
The answer, as in outer space propulsion, could involve using surplus electricity to split water into hydrogen and oxygen. This produces a storable and transportable commodity in the form of hydrogen fuel. When the energy is needed, it can be released by recombining it with oxygen from the atmosphere. This can either be done in a fuel cell to produce electricity again, or by burning it in a combustion engine or a hydrogen gas burner.
Welsh start-up firm Riversimple—along with major car manufacturers Toyota and Volkswagen—is already producing hydrogen fuel-cell cars. So if the hydrogen is produced from solar energy in the same manner as Cornell’s satellite, this space technology could become part of your everyday life sooner than you think.