Why develop the water on the moon could open space research



Lovers of lunar mines were particularly happy this week when researchers claimed that they had found definitive proof that there is water ice on the surface of the moon. There is even more water ice than we thought up there, and we know exactly where much of it is. That might make it even easier to exploit this water in the future.

Long before this discovery, researchers wanted to brag all the water lurking on the lunar surface. It is a resource that could be incredibly valuable for future long-term missions on the moon, because water is essential for life to function here on Earth. It can be recycled in a lunar habitat or used for drinking water or swimming. It can also be used to grow plants on the moon that are needed to feed future lunar inhabitants.

But perhaps the largest and most direct application for moon water is making rocket gas. The main components of water – hydrogen and oxygen – are two of the largest materials currently used to power rockets. And making the rocket propellant from the water on the moon could drastically reduce the cost of ambitious missions in space. At this moment, rockets that leave the earth must carry all the propellant that they need. But by using moon ice, rockets can refuel as soon as they are in space, allowing them to reach locations in the distance for less money.

"The idea would be to start a supply chain outside the earth for certain products – especially for water as propellant – so it could be much easier to move from one body to another," Julie Brisset, a research assistant at the Florida Space Institute The edge.

Getting everything in space is expensive. If you want your satellite to become disconnected from the earth's gravity, you need a lot of propellant to feed the ride to the runway. The bulk of the weight of a rocket at launch is only the propellant gas needed to get the thing into space. And the deeper you want to go into space, the more propellant you need. More energy is needed to move further and further away from the attraction of the planet. So missions to deeper space become even more expensive to pay for all the extra propellant gas needed to get there and the larger rocket to house that propellant.

But what if, instead of taking all the propellant you need from the earth, you refuel your petrol tank with propellant that is already in space? Then deep-space missions become more like cross-country road trips. "Imagine you had to drive to Denver and there were no petrol stations on the way and you had to take all your gas from New York," George Sowers, a professor at the Colorado School of Mines and former vice president at the United Launch Alliance, explains The edge. "You probably would not be able to do it in your car, you'd have to get all the fuel you needed." That's why the idea of ​​lunar mines is so appealing. Water from the moon can be extracted, torn apart in rocket fuel and transported to a propellant depot, either in the vicinity of the moon or in a low orbit around the earth. Then rockets do not have to be so big to house all their propellant. They can easily moor at a depot and refuel for longer journeys to space.

The transportation of propellant from the moon to other locations in space is not nearly as expensive as transporting the earth. The moon has a sixth of Earth's gravity, which means that less energy is needed to break off the surface. Sowers recently conducted an analysis of how much it would cost to transport the gas from the moon to different locations from space. And getting moon water to a low orbiting earth, for example, is still cheaper than sending it from the earth, even though our planet is getting closer. "If you want to use that propellant in a low orbit in the earth, it can still be 20 or 30 percent, using the propellant of the moon or the propellant of the earth," says Sowers.

Scientists have been fantasizing for decades now to turn moon water into rocket fuel, as shown by the fact that the moonstocks may be a prime number for mining. In 1994, a joint probe from NASA and the US Army Clementine found evidence that water exists in craters on the poles of the moon. These places never see the light of the sun and never reach temperatures above -250 degrees Fahrenheit. Multiple missions to the moon since have indicated that water can also be present at these locations. In 2009, NASA hit a spaceship called LCROSS in a crater at the south pole of the moon to see what kind of material the impact had occurred. NASA discovered that there was about 5 percent water in what was ejected.


A map of exposed moon ice made with data from the Chandrayaan-1 spacecraft.
Image: NASA

However, research published this week in the Proceedings of the National Academy of Sciences indicates that some parts of the Moon may overflow into water. Researchers from the University of Hawaii and Brown University analyzed data collected from the Indian spaceship Chandrayaan-1, which was launched on the moon in 2008. Using one of the instruments of the vehicle, they could locate parts of the ice on the moon through the reflectivity of the water. They also observed these locations in infrared light, allowing them to determine whether the water was in ice form and not in vapor or liquid. They not only confirmed that water ice is exposed on the lunar surface, but some parts of the ground consist of 20 to 30 percent of ice. Depending on how deep the surface of the ice is, it can be a lot of food for rocket gas.

"We really do not have to be that Which concentrated everywhere, "says Phil Metzger, planetary physicist at the University of Central Florida and co-founder of NASA & # 39; s Swamp Works at Kennedy Space Center." We need only a few locations to have a higher concentration to get enough water. to provide all space needs for the next 30 years. "

A propellant depot in a low earth orbit opens many opportunities for new types of missions in space. An idea is something that is called a tugboat – a rocket that stays in space and refuel time and time again to transport satellites to their final destinations. At the moment, satellites coming into high lanes above the earth are used in a first runway and then for six months to a year, where they slowly pull themselves up with thrusters on board. During that time, the satellite can not do its job, so it does not make money. But with a tug, satellites can be deployed in much lower lanes with smaller missiles, and then a reusable rocket that is already in space can drag the probe to the final track in just a few days. That saves money from satellite operators: they do not need a large rocket to get their load in space, and they have more time to make money with their probes.

So yes, Moon-water-as-fuel is attractive, but it will not be easy to start extracting water into space. First of all, there must be an extensive prospecting campaign. Thanks to the PNAS study, researchers have actually made a map that shows where the juiciest lumps of water ice can be found on the moon piles. The next step is to send landers and robbers to those areas to find out what the best location is to target and what the consistency of the ice is. Scientists still do not know whether the ice is in the form of slush that is mixed with the dirt or that it looks like solid stones fused with other surface material. "We know how to design the equipment to extract it, we just do not know which set of equipment to use," says Metzger.


NASA has been working on robot designs that can be used to create dirt from the moon and Mars.
Image: NASA

An idea is digging up the lunar floor with a digging robot that drags the materials to a processor. That processor then separates the ice from the ground by means of heating and breaks the water into the basic components with electricity. Part of the resulting fuel is then used to drain the rest of the water from the moon onto a transport vehicle and to send it to any propellant depot in the room.

Of course, this will all be expensive. "It comes down to a cost analysis," says Metzger. "Is it cheaper to launch rocket fuel from the earth, or is it cheaper to launch the equipment once in space and then to maintain and use that equipment to continually make rocket fuel in space?" Based on analysis conducted by Metzger, Brisset, and Sowers estimate that it will take a decade to invest in lunar mines to be profitable. But because moon mining is so risky, it is possible that not many venture capitalists want to indent immediately.

That is why the team suggests that NASA should be involved by partially financing the early mining development efforts. In this way, commercial investors will face problems sooner if a credible government body is involved and bears part of the costs.

NASA would not only make investors a pleasure, the space agency has also suggested that every year up to 100 tons of propellant gas is needed to provide vehicles that leave the lunar surface with a base, according to Sowers' analysis. If they were to send everything from the earth, it would cost about $ 3.5 billion a year. The savings in making moon fuel can make missions to the moon and Mars cheaper. "It would make Mars missions cheaper and it makes virtually everything we do affordable outside of the earth," says Sowers. For example, the use of moon propellant for refueling missiles would reduce the cost of going to the moon from Earth by a factor of three, according to Sowers. That is an important detail, given that NASA wants to do human missions to the moon again.

"I have been saying for years that water is the oil of space," says Sowers, adding, "If NASA intends to create a permanent human presence on the moon, NASA must first build a production facility for propellant gas. . "


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