NASA-NOAA Suomi NPP Satellite Team Ward Off Recent Space Debris Threat

While space debris was the uncontrolled adversary in the award-winning space thriller film "Gravity," space debris, also known as "space junk," is an ongoing real-life concern for teams managing satellites orbiting Earth, including NOAA-NASA's Suomi National Polar-orbiting Partnership, or Suomi NPP, satellite. It is not unusual for satellites that have the capability of maneuvering to be repositioned to avoid debris or to maintain the proper orbit.

On an otherwise quiet Sunday on September 28, the Suomi NPP mission team was monitoring a possible close approach of a debris object. By early evening, the risk was assessed to be high enough to start planning a spacecraft maneuver to put the satellite into a safer zone, out of the path of the object classified in a size range of 4 inches up to 3.3 feet.

It was determined that the object (travelling at almost 17,000 mph) was approaching at a nearly "head on" angle, and could potentially only miss the Suomi NPP satellite by approximately 300 feet on Tuesday, September 30, if no action was taken. With that knowledge, the decision was made at 1:30 p.m. on Monday, September 29, for NOAA's Satellite Operations Facility, or NSOF, in Suitland, Maryland, to reposition Suomi NPP. Operational control as well as planning and execution of all Suomi NPP maneuvers take place at NSOF.

"Because Suomi NPP moves at a similar speed as the debris object, if there had been an impact, it would have occurred at a combined speed of nearly 35,000 mph. This would have been catastrophic not only to the satellite, but would result in thousands of pieces of new debris," said Harry Solomon, Mission Manager for Suomi NPP at NASA's Goddard Space Flight Center.

Space around Earth is littered with numerous man-made objects that could potentially collide with operating spacecraft and each other (creating more debris). There are more than 20,000 objects being monitored by the U.S. Department of Defense for satellite managers around the world.

Only about 1,000 of those 20,000 objects are operating spacecraft. The rest of the monitored space debris ranges in size from the size of a softball, to massive rocket bodies, all orbiting uncontrolled at relative speeds averaging about 22,300 mph in low-Earth orbit, where the majority of the objects reside.

Yet it is the unknown, often smaller, untracked objects that pose the biggest threat. "If a spacecraft is lost due to being hit by debris, the odds are the satellite will be hit by something the trackers can't see," said Nicholas Johnson, NASA chief scientist (retired) for orbital debris at Johnson Space Center in Houston.

That is exactly the scenario Solomon and his counterpart, Martin England, mission operations engineering lead at NSOF hope will never happen.

Risk Team Monitors Unmanned Missions Threats for NOAA and NASA

While NASA's Johnson Space Center manages monitored debris threats for spacecraft related to U.S. manned missions such as the International Space Station, the responsibility for unmanned missions managed by NASA falls to the Conjunction Assessment Risk Analysis, or CARA, team operating out of NASA Goddard.