Jeffrey LewisANGELS

Keepin’ it work safe for the boyz and
grrls with the .gov and .mil IPs

Jeremy Singer at Space News reports (Yahoo! has the full text) that the Air Force Research Laboratory is “planning a small experimental satellite that would orbit in close proximity to a host spacecraft and keep tabs on their surrounding space environment” in geostationary orbit:

The Angels satellite will be launched into a geostationary orbit for an experiment that is expected to last about a year, according to the request for information. The Air Force hopes to extend the mission for another two years, according to the request for information.

Geostationary orbit is a belt of space some 36,000 kilometers above the equator that hosts most communications satellites. The Air Force chose that orbit because its distance from Earth’s surface makes it less visible and more difficult to monitor than lower orbits, [Tom] Caudill [the space surveillance technical area lead at the laboratory] said.

The Angels spacecraft would launch along with a yet-to-be-determined host satellite that it would shadow in orbit, Caudill said. The launch likely will be arranged by the Defense Department’s Space Test Program, he said.

Jeremy noticed the program when the Air Force Research Laboratory released this solicitatiton for the Autonomous Nanosatellite Guardian for Evaluating Local Space or ANGELS.

I am not sure how ANGELS relates to a similar DARPA program, Spectator, that Lt Col Jim Shoemaker (USAF), Program Manager, Tactical Technology Office, DARPA Space Activities, mentioned at DARPATECH 2005:

… might also want to validate the concept of a host vehicle inspector, a nanosat carried by a host satellite, able to be released to inspect its host to assist in anomaly resolution, such as an incompletely deployed solar array. These are some of the ideas we’re exploring on a new program called Spectator. We’re not exactly sure what Spectator should be, and we welcome your input in defining the program.

Then again, from that description, I am not sure DARPA knows either. They seem to be duplicative, if not coextensive.

The United States does need to improve its space situational awareness, especially in geostationary orbit (GEO). The catalogue for low earth orbit only contains objects larger than 10 cm in diameter—larger than a baseball. Objects just a fraction of that size can cause the loss of a satellite. A piece of debris 1 cm in diameter contains more potential energy than is practical to shield against in orbit. The catalogue is even less complete for geostationary orbit, where only objects larger than 1 meter are tracked and catalogued.

The idea of using small satellites to monitor and, perhaps, protect satellites has been kicking around for a while—Matt Bille, from ANSER, co-authored a pair of papers calling for a “microsatellite space guard” in 1999 and 2000:

While ANGELS will operate in geostrationary orbits, Bille et al expect the first space guard satellites in low earth orbit (LEO) building on the XSS, DART and Orbital Express programs.

Given DART’s little accident while conducting an rendezvous (RSO for the hipsters), I think some rules of the road for such proximity operations would be in order—before the Chinese start doing it, too, and everybody in this town freaks out.