Space debris fuel
In a sci-fi thriller
(2013) an American astronaut finds himself in outer space after the destruction of a ship as Russia detonates a spy satellite with a rocket and creates a rapidly expanding cloud of space debris. Ironically, but recently this scenario was repeated in reality, when Russia
shot down an old Soviet satellite
, as part of an anti-satellite missile test. The likelihood that space debris could penetrate a spacesuit during a spacewalk is typically 1 in 2700, but Russian tests increased that risk by 7%.
Space debris is a danger to active satellites and spacecraft. Presumably, Earth’s orbit will become impassable when the risk of collision is too high. Today, when most of the space debris is cataloged, so far there is no particular problem with this. All world space powers scan space for the presence of debris, of which there is a lot in low orbits: inoperative satellites, booster blocks and debris. It is very difficult to solve the space debris problem quickly due to financial and political problems. Old satellites, which have served their purpose, must either be introduced into the Earth’s atmosphere for disposal at the “spaceship graveyard” in the Pacific Ocean, or put into a “burial orbit” if the device is far from the Earth.
Scientists asked the question: why not develop a spacecraft that will dispose of space debris directly in space? And a prototype of such an apparatus exists. The idea of creating an apparatus for the disposal of space debris is based on the processing of space debris into fuel.
Not littering will not work
Space debris is non-functional man-made objects in low-Earth orbit that no longer perform a useful function. These include non-functional spacecraft and launch vehicle stages, as well as debris, paint stains, solidified liquids ejected from the spacecraft, and unburned particles from solid propellant rocket motors.
about 20,000 artificial objects in orbit above the Earth, including 2,218 active satellites. As of January 2019, there were 128,000,000 debris in orbit less than 1 cm in size, about 900,000 debris 1-10 cm in size, and about 34,000 debris over 10 cm in size. which can group with man-made debris and increase the risk of collision. This poses a danger to spaceships: even the smallest objects cause damage, especially to solar panels, telescope optics and star trackers, which cannot be easily protected by a ballistic shield.
Over the years, Earth’s orbit becomes more and more cluttered. According to European Space Agency (ESA)Humanity has launched 12,170 satellites since the beginning of the space age in 1957, and 7,630 of them remain in orbit today, but only about 4,700 are still operational. This means that nearly 3,000 non-functional spacecraft are orbiting the Earth at tremendous speed, along with other large and dangerous debris. For example, the orbital speed at an altitude of 400 kilometers (the altitude at which the ISS operates) is 27,500 km / h. At these speeds, even tiny debris can wreak havoc on a spacecraft. ESA estimates that there are at least 36,500 debris in orbit over 10 centimeters wide, 1 million objects ranging from 1 to 10 cm across, and over 300 million objects ranging from 1 mm to 1 cm.
“Cascade effect” (
), which in the long term may arise from the collision of objects and particles of space debris, we can assume that it is already making itself felt, although the cataclysm of the scale of “Gravity” is still far away. Evidence of this may be the collision of two satellites with each other. The most famous such incident occurred in February 2009, when an inoperative Russian satellite
crashed into a communications ship
, forming over 2000 debris.
Under the existing conditions of debris in low Earth orbits, when measures to reduce the technogenic debris of space remain only theoretical, the cascade effect can lead to a catastrophic increase in the amount of space debris in low orbit, and, as a consequence, to the practical impossibility of further space exploration.
spring-cleaning
As the problem escalates, organizations around the world are trying to find solutions – from magnets to space claws and harpoons. Space debris can be counteracted in different ways: crushing large space debris, de-orbiting debris or de-orbiting debris,
or its processing into fuel. It is not possible to use just one countermeasure for all types of garbage. For example, small space debris cannot be caught with a net, and large space debris is useless to stop with gas.
Basically, there are two directions for combating space debris:
- crushing of space debris directly in orbit;
- deceleration and removal of large space debris from low orbits for subsequent combustion in the atmosphere; or removal of space debris from geostationary orbit to disposal orbit.
How the garbage collector works
Moreover, both methods have disadvantages associated with the formation of debris of a finer fraction, the fall of unburned debris to the Earth, and the clogging of higher orbits.
The easiest way to clear outer space is to suspend space activity for a decade, while the Earth’s gravity does its job, but then humanity will stop developing. If nothing is done, then at the current rate of growth of space activity, soon we will simply not be able to launch spacecraft due to debris in orbit and will also stop developing.
American company Cislunar Industries develops a space “foundry” to melt debris into uniform metal rods. And the propulsion system from Neumann Space can use these metal rods as fuel – their system ionizes the metal, which then creates thrust to orbit. It’s like making a gas station in space. SCM converts debris into fuel, which allows the spacecraft to gradually rise to higher orbits, up to the disposal orbit (over 40 thousand km), clearing space.
Most space propulsion systems use gas as fuel. Even in liquid form, fuel takes up a lot of space and is not very suitable for space travel. And if there is a problem, as happened with mission of the Challenger shipthe results can be disastrous. It is better if the propulsion system runs on solid fuel, which is much safer than an explosive liquid or gas.
Ion engine
Neumann space announces the development of a low-thrust ion thruster that uses electricity with powerful pulses similar to arc welding. Ion engines Are spacecraft engines powered by electricity. Prototypes have been around since the 50s, and some have even been tested in space. Neumann’s device is slightly different from earlier prototypes, but has similar components. When the system is triggered, an electrical spark is generated between the anode and cathode.
Electricity is applied to metals such as titanium or magnesium, or any solid, conductive fuel rod, to produce plasma and burn off charged gas through the back of the engine, creating thrust.
Simplified diagram of the Neumann engine
Paddy Neumann himself
The author of the project, Dr. Paddy Neumann, as a student, participated in a plasma diagnostics project, which was to diagnose how hot it is, how dense it is, how fast it moves, etc. Analyzing his results, he was able to determine the average effective plasma velocity, which was 23 km / s. He, that from this you can make a rocket.
One performance metric that engineers love to talk about in this space is called specific impulse… Specific impulse is essentially the amount of push that can be obtained from a given weight of fuel. Thus, a higher specific impulse means that the fuel is used more efficiently. This is just one element to consider when designing a space engine. In addition, since it is very expensive to put something into orbit, it is very convenient to have a fuel that allows it to do it with less mass or volume. Specific impulse is measured in seconds. When Dr. Neumann began testing his engine, existing ion thrusters delivered 3500 seconds of specific impulse. NASA Experimental System HiPEP might work a little better, 10,000 seconds. After testing several different fuels, Dr. Neumann published my results: magnesium as fuel and had a specific impulse of 11,000 seconds. So, three times better than what is used today.
While Neumann’s engine cannot compete with chemical-fueled internal combustion engines to propel a ship into space, it can be installed on smaller ships or satellites to keep them in orbit. The moon and sun will always pull the satellites a little behind them, so you need a small motor to keep them in the correct orbit.
Last year, Neumann Space received $ 2 million in seed funding from government grants. They say that they plan to test the Neumann engine in space in the near future.
Now a kind of ecosystem is emerging in near-earth space. In this ecosystem, as in any other, there are “creatures” that “live”, “feed”, perform their functions and, “dying”, provide food to other creatures. And the creatures that “feed on carrion” can and should be the collectors of space debris in the broadest sense of the word.
