MISSION CLEARSPACE

Remember Gravity? The film in which NASA's Explorer Space Shuttle is hit by high-speed Space Debris. Well, Space Debris isn't just fiction. It's a huge problem faced by every space-faring nation. 

Space debris is a term used to define the unwanted man-made kaput objects present in the space. This includes the inoperative artificial objects like satellites, spacecrafts and their fragments after annihilation. 

Since colossal amount of debris is present in the outer space, their counting act as a conundrum for mankind. They are considered as minacious and act as an impediment for other satellites and spacecrafts.

34,000 pieces of space junk larger than 10 cm are now in orbit around the Earth, along with 900,000 pieces larger than 1 cm. They arise from hundreds of space missions launched since Sputnik-1 which paved the way for the beginning of the Space Age in 1957. 

Traveling at a speed equivalent to 30,870 km/h, even the tiniest piece of debris can threaten, for example, the ISS (International Space Station) and other satellites, and create more debris when it collides. 

Today we will explore what are the different techniques being developed and used by government-owned space agencies and private companies around the world.

RemoveDEBRIS

Developed by the researchers at the University of Surrey, it was launched on 2nd April 2018 from Cape Canaveral on a Falcon 9 spacecraft. One of the CubeSats (mini satellites), called DebrisSat 1, deployed a balloon meant to simulate a piece of space debris. 

The other CubeSat, called DebrisSat 2, was released and the RemoveDEBRIS satellite undergone a series of maneuvers to obtain data and images using both lidar and optical cameras. A harpoon connected by a tether was fired at a plate attached to an arm extending from the RemoveDEBRIS platform itself

After that, they deployed a large sail that dragged the satellite against the residual atmosphere bringing the satellite down lower and lower and burning it in the atmosphere.

D3

D-Orbit an Italian company had tested a new way to take out the trash: a kind of plug-and-play motor that sends any satellite it is attached to towards a heat death in the atmosphere. They launched a test satellite D-Sat under a 3U -CubeSat mission with the " (D-Orbit Decommissioning Device) "called D3, on 23 June 2017, and finished up this fall—their first attempt at keeping satellites from adding to the space junk problem. 

D-Sat swirled about Earth for around three months, performing a few experiments. At the end of its brief life, D-Orbiters got ready to put D3 into action. Before the D3 thrust, the procedure called for them to spin the satellite around, fast, at 700 times per minute, to make it stable. 

The D-orbit motor was fired, but instead of orbiting, a misalignment of the motor with the satellite center of gravity caused a tumble during the motor's burn. It's few millimeters of offness meant that some of D3’s thrust set the satellite spinning, instead of simply pushing it. Right now, D-Orbit is only working to put D3 on as-yet-unlaunched satellites.

Laser Broom

The U.S.  Air Force first began exploring the laser broom idea in the 1990s. Scientists use the laser to vapourize a tiny bit of the piece of space junk,and the resulting puff of vapour would create enough drag to slow down the target so it would fall into the atmosphere, where the entire thing would burn up. Ground-based lasers avoid launching costs and propellent limitations.

Whipple Shield

This technique is used by ISS to tackle the space debris problem. The Whipple shield uses the debris velocity to stop it. At 4 km/s and higher, the energies involved are so immense that the projectile itself breaks apart and vaporizes on impact. 

It takes advantage of this by creating a shield that is composed of several thin sheets of armor separated by space. So when a meteoroid or debris does strike it, it first breaks up into thousands of smaller superheated fragments thereby spreading the energy of the impact over a larger area for the following shield layer.

e.Deorbit

e.Deorbit is ESA's (European Space Agency) Active Debris Removal mission which will target ESA's own satellite in a heavily trafficked low earth orbit (LEO) to capture it then bring it down to burn up in the atmosphere. Its launch is scheduled for 2025. 

Right now there are three kinds of challenges to overcome. The first is to identify the target as it tumbles out of control then find a safe way to close in then synchronize orbital paths. The second challenge is to capture it securely. Two alternative mechanisms are currently under study- one would use a robotic arm the other would employ a net. 

The final challenge will be to convey this massive item of debris down in a safe and controlled manner.

ClearSpace-1

The ClearSpace-1 mission will be carried out by a commercial consortium led by Swiss startup ClearSpace. Planned for launch in 2025, the mission will target a spent upper stage from an ESA Vega rocket orbiting at 720 kilometers above the Earth. There, ClearSpace-1 will rendezvous with a target, which will be traveling at close to 8 kilometers per second.

 After making its approach, the spacecraft will employ ‘tentacles’ to reach beyond and around the object.

 During the first mission, once ClearSpace-1 secures its target, the satellite will use its own propulsion to re-enter Earth’s atmosphere, burning up in the process and destroying the piece it embraced. In future missions, ClearSpace hopes to build spacecraft that can remove multiple pieces of debris before the satellite burns up with all the debris onboard.

In the end, we would like to say that it's high time that we find a solution for removing space junk otherwise the consequences will be catastrophic and will certainly hinder any plans of future spacecraft and humans venturing beyond earth.

Thanks for reading. IEEE SB NITP would like to once again remind its readers to obey the guidelines as issued by the Government and WHO. Stay home and stay safe. Please drop your views in the comment section.