Orbiting robots could help fix and fuel satellites in space

For more than 20 years, the Landsat 7 satellite circled Earth every 99 minutes or so, capturing images of almost all the planet's surface. The craft that observed the changing globe revealed melting glaciers in Greenland, the growth of shrimp farms in Mexico, and the extent of rainforest destruction in New Zealand. After Landsat 7 ran out of fuel, its useful life ended. Regular servicing has not been an option in space.

NASA has a possible fix for such satellites. In a few years, the agency plans to launch a robot into the sky and maneuver it to within range of Landsat 7. The robot will use a mechanical arm to catch hold of it.

It would be the first time a satellite would be refueled in space. There are a number of planned public and private ventures that are intended to use robots to repair and improve the billions of dollars worth of satellites.

Eventually, efforts like these could lead to better and cheaper satellites that can be used to provide better weather forecasts, give better views of the Universe, and lower the cost of internet and cell phone networks. They could even enable a new wave of in-orbit construction, with armies of robots building satellites, space stations, and even Mars-bound spaceships.

Giving satellites longer lives

There are 4,852 satellites in the sky, playing crucial roles in communications, remote sensing, and other tasks. Most of them were launched with the knowledge that if anything broke there was no way to fix it. Satellites need fuel to adjust their orbits. They may become so much space junk that they will add to the already large stream of debris encircling the globe.

Brian Weeden is the head of an industry group called the Consortium for Execution of Rendezvous and Servicing Operations. You can't change the oil. You can't fix anything. You have to use it for 10 years. How complicated is that car? That is what we have been doing with satellites.

Engineers build redundant systems and pack in as much fuel as they can fit to keep satellites working. A modern communications satellite can cost as much as $500 million.

Repairs on the Hubble Space Telescope and the construction of the International Space Station have been done in part by astronauts. The cost of sending humans into space has led to the development of robots to do the job.

Carl Glen Henshaw is the head of the robotics and machine learning section at the US Naval Research Laboratory.