SALT LAKE CITY — SpaceX is encouraging satellite operators to use a new space safety platform the company has developed to reduce the risk of collisions in congested low Earth orbits.
The company used a side meeting at the Small Satellite Conference here Aug. 24 to discuss its new space-safety.com platform. The system is available free of charge to satellite operators.
The system leverages Stargaze, a space situational awareness, or SSA, system the company announced in January. Stargaze uses images from star trackers on Starlink spacecraft to detect and track objects in orbit, calculate orbits and use that information to detect potential conjunctions, or close approaches, with other spacecraft.
Stargaze currently tracks about 16,500 objects in low Earth orbit, said Mike Hoot, a software engineer at SpaceX, during the presentation. That is about 48% of the public catalog maintained by the U.S. Space Force on its Space-Track.org system. Stargaze, he said, can detect objects as small as a meter across, meaning it cannot track many cubesat-class satellites or small debris.
For the objects Stargaze can detect, he said the system can see them up to 10 times an hour because of the large number of sensors. “This is useful for tracking really big stuff and, especially, maneuverable satellites,” he noted, with updated orbits for objects calculated within five minutes of a new Stargaze observation.
“Stargaze is not a standalone replacement for radar systems today” used for tracking objects in low Earth orbit, he said. “There are things radar systems can see that Stargaze cannot. But we think of it as a very useful complementary system.”
The SpaceX space-safety.com platform calculates potential conjunctions using Stargaze and other data, including ephemerides submitted by satellite operators that provide their own determinations of the orbits of their satellites, along with planned maneuvers.
A key aspect of SpaceX’s service is its ability to do rapid conjunction screening. Hoot said that while the Space-Track service checks for conjunctions three times a day, space-safety.com screens more than 500,000 ephemeris files daily, including those submitted by satellite operators and those calculated by Stargaze.
He said that notices of potential conjunctions, called conjunction data messages, or CDMs, are generated within a minute of an ephemeris submission.
The platform is currently available only to satellite operators who are willing to share ephemerides. Hoot said more than 30 satellite operators provided data on more than 700 of their objects in the last week.
The system is also free to participating operators. “We do satellite internet. We’re not trying to make money off SSA,” he said.
SpaceX’s motivations, though, are not entirely altruistic. The company is by far the largest satellite operator in the world, with more than 11,000 Starlink satellites in orbit. “Starlink is highly invested in trying to make low Earth orbit safe,” he said.
Much of the presentation offered lessons learned for safe operations in low Earth orbit. That included sharing accurate ephemerides and planned maneuver data, and the need to compensate for volatility from space weather by publishing ephemerides more frequently during solar storms that can increase atmospheric drag on satellites.
Another is dealing with what the company calls the “launch COLA gap,” a reference to collision-avoidance screenings done before launch that cover the first several hours after the launch of satellites. Because it can take days for SSA systems to start tracking newly launched satellites, that creates a gap where those new satellites are, in effect, invisible to other operators.
Hoot said that SpaceX’s recommendations include publishing ephemerides as soon as possible after launch as well as avoiding launching directly into densely populated orbits, especially for new operators. “If you’re learning to drive, you wouldn’t want to take your first driving lesson on the freeway.”