This article originally appeared in the Sept. 10, 2018 issue of SpaceNews magazine.
When Indonesian satellite operator PT Telkom lost contact with an 18-year-old satellite in 2017, the company initially blamed the problem on an antenna pointing issue.
The next day, ground-based telescopes showed that the satellite, Telkom-1, was shedding debris, indicating something more dire than a pointing problem. The initial misdiagnosis of the satellite’s catastrophic failure was at least partly due to the lack of direct and immediate observations of the geostationary satellite.
The U.S. Intelligence Advanced Research Projects Activity (IARPA) wants to change that.
In April, the U.S. intelligence community’s version of the Pentagon’s Defense Advanced Research Projects Agency split $45 million between four companies — Boeing ($12.4 million), Lockheed Martin ($11.9 million), Honeywell ($8.7 million) and Applied Technology Associates ($12 million) — to image objects in geostationary orbit with 50-centimeter resolution or better, and to complete data collection preferably within one hour. Eleven companies competed for the funding.
The catch is companies can’t beam radio frequencies at GEO like the Air Force’s $900 million S-band Space Fence that Lockheed Martin is building. Only optical systems are allowed. “What we are trying to do is develop ground-based passive approaches to imaging GEO,” said Merrick DeWitt, IARPA’s program manager for Amon-Hen, a two-year-old effort named after a hill in J.R.R. Tolkien’s The Lord of the Rings trilogy. “We are not illuminating the objects with lasers in any way, or even RF for that matter.”
Optical systems have their limitations. The biggest is that they only work at night, and even then are susceptible to interference from cloudy skies. But ground-based optical systems are cheaper than most alternatives, DeWitt said.
“The hardware will cost less than $25 million, which is actually a fairly ambitious goal,” he said.
Optical systems have the potential to produce much sharper images as well, he said. “There’s a limit to the resolution that you can potentially get with RF techniques that you can overcome with the shorter wavelengths of optical light,” DeWitt said.
The rash of on-orbit satellite failures last year — Telkom-1, SES’s AMC-9, three of Orbcomm’s OG2 satellites and EchoStar’s brief loss of control over EchoStar-3 — forced the satellite industry to pay more attention to space situational awareness, the real-time monitoring of the near-space environment. And as large constellations of remote sensing and telecom satellites start launching, regulators and operators are debating what requirements should be mandated to preserve the space environment.
Martin Coleman, head of the Satellite Interference Reduction Group, said that even though his organization is focused on radio-frequency issues, space debris has become an area of concern.
“We are involved in it because we need to understand it,” he said. The Space Data Association, which collects and shares information about satellite locations, handles more space situational awareness work, he said, but space debris is becoming increasingly important to his group’s members.
“We can’t keep launching [satellites] if you’ve still got debris,” he said.
IARPA has set 2021 as the deadline for the four companies designing imaging systems for the GEO arc to prove their work. As a research and development agency, IARPA will then seek to transition the solutions to partners that can put them into operational use. DeWitt said the U.S. Air Force Research Laboratory is interested in being one such transition partner.
Amon-Hen has the potential to image regions outside of GEO, but faces limitations in lower orbits, he said. That’s because objects in GEO appear stationary from Earth’s surface, and therefore don’t need tracking systems to ensure a clear image. Satellites and debris closer to Earth will move across the sky and be more difficult to resolve. DeWitt estimated Amon-Hen could potentially resolve objects if they are halfway to the GEO arc.
