Thousands of satellites are orbiting Earth right now and projects such as Starlink are launching even more satellite constellations to the already crowded orbit. With important functions such as GPS navigation, weather monitoring and communications, refueling might just be the difference between a functional satellite and a piece of yet another free-floating space junk

'When a satellite runs out of fuel, and you don't have a way to refuel it, that satellite stops working,' says John Wen of Rensselaer Polytechnic Institute, according to Phys.org. 'When that happens, a new satellite is launched to replace the existing satellite.'

Wenheads up a group of researchers at Rensselaerwho are working withNASA to solve the space debris problem: a robot that could capture a satellite, pull it into dock and refuel it.

'Our part of the research is to specifically look at transporting a massive satellite, which is way beyond the capacity of this robot arm on Earth under gravity,' Wen says.

Maxar Technologies, a Colorado-based space technology company, is developing the thin, two-meter-long robotic arm. It has gears and joints, which give it flexibility, and is able to handle large satellites. The arms movements are controlled by complex algorithms to ensure that it accurately transports and docks satellites for refueling.

Whats it like to capture a satellite in space? Not unlike dragging a large bus along the ice in an ice rink, Wen says. It is easier to move a heavy object on ice and in microgravity but the movements must nonetheless be precise.

'There will be no human in space to intervene,' Wen says. 'It's all relying on the ground operator. So, we have to do extensive simulation both in software, as well as in hardware, to make sure this operation is safe.'

The team is currently running simulations at Rensselaers Center for Automation Technologies and Systems Lab. For physical simulations of zero gravity, researchers use what is essentially an air hockey table where a small satellite can float near the surface and a smaller robotic arm makes the necessary movements. The team is also running computational simulations.

The robotic arm is just one of the projects NASA has in the works: its Satellite Servicing Projects Division is developing various technologies to enable the servicing of satellites, as well as satellite disposal. One such project is Restore-L, slated to launch in 2022, a robotic spacecraft that can grasp, repair and refuel satellites to extend their lives.

In October, Northrop Grummanlaunched its Mission Extension Vehicle (MEV-1) with the purpose of refueling Intelsat 901, a commercial satellite that has been in orbit since 2001, and performing some orbit maintenance. MEV-1 is supposed to extend the operational life of Intelsat 901 by five years and then go on to potentially fix other satellites. It still remains to be seen whether the mission will be successful.

The work researchers and NASAare doing on satellites will lay the groundwork for deep-space missions as well. 'It's getting increasingly difficult to fly heavy payloads into orbit, so when we talk about a lunar mission, Mars mission, et cetera, increasingly the assembly will have to be done in space,' Wen told Phys.org. 'The robotic technology we're working on now will be the foundation of such work in the future.'

Photo credit: Rensselaer Polytechnic Institute

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Robots Will Refuel Satellites in Space, Extend Operations - Asgardia Space News