Incident Raises Questions, Even if Debris Hazard isn’t Great
The breakup of an aging U.S. Air Force weather satellite Feb. 3 has drawn fresh attention to the always smoldering orbital debris issue, including the U.S. government’s orbital data sharing practices.
According to the Air Force, the Defense Meteorological Satellite Program Flight 13 satellite (DMSP-F13), which launched in 1995 and had long been relegated to backup duty, broke up after its power system experienced “a sudden spike in temperature” followed by an “unrecoverable loss of attitude control.” Some experts speculated that the event, which left more than 60 pieces of observable debris in an orbital belt heavily used by environmental, weather and imaging satellites, was caused by a catastrophic battery failure.
The Air Force publicly confirmed the incident Feb. 27 — more than three weeks after the fact — after being prompted by questions from the news media. The press inquiry, in turn, was prompted by Twitter posts by one well-known expert — T.S. Kelso of the Center for Space Standards & Innovation — that were based on information he had gleaned from the Air Force’s publicly available online database of Earth-orbiting objects.
The delayed disclosure drew criticism from some quarters that the U.S. Defense Department — operator of the Space Surveillance Network, the world’s best — should have alerted other satellite operators, in particular U.S. allies, that a debris-creating event had occurred. Indeed, officials with European government space agencies said they were never formally notified by the Pentagon of the DMSP-F13 event, despite the fact that they operate satellites in similar orbits.
But these officials also said they hadn’t expected any such notification, and that there are no protocols in place for that to happen. They also noted, with appreciation, that the Pentagon’s Joint Space Operations Center, which directs and supports space operations of all types, routinely warns them of impending close approaches to their satellites — even when classified U.S. assets are involved.
It should be further pointed out that the Defense Department doesn’t limit this courtesy to close allies. China, for example, also receives such alerts, the reason being that any sort of orbital collision, regardless of whose satellite is involved, increases the debris hazard for all.
Whether or not the Pentagon needs to be more proactive in alerting the broader space community of significant debris events — and the DMSP-F13 breakup would seem to qualify — is a fair question. Generally speaking it’s not in the U.S. military space culture to say any more than is necessary, and the minimalist approach seems to have worked fairly well to date — notwithstanding occasional complaints from commercial satellite operators.
But the world in space is changing. The number of operators, both government and commercial, is growing rapidly, and some of these relative newcomers are deploying small satellites in numbers that were unheard of just a few years ago. Meanwhile, a new breed of companies have cropped up in the last year with plans for mega-constellations — in one case consisting of more than 4,000 satellites — for Internet delivery to the masses. While it might be tempting to dismiss these proposals as pie in the sky, at least two have attracted serious money from investors and should be regarded accordingly.
The trends should lead the Defense Department to at least reconsider its selective, albeit inclusive, data sharing policy. Just the sheer number of operators, and of satellites being deployed or planned, will undoubtedly complicate the current practice of providing targeted alerts of close approaches. It could be that more data made more routinely and widely available will ultimately lead to a safer orbital environment.
The DMSP-F13 breakup also is a good reason for the Air Force to rethink its criteria for decommissioning aging satellites. As they say, hindsight is always 20-20, but if in fact a catastrophic battery failure caused the event, it might have been avoided had the satellite’s energy sources been disabled or depleted — a process known as passivation — a bit sooner.
DMSP-F13 was consigned to backup duty in 2006, and the Air Force said its loss will have a minimal impact on its overall weather monitoring capability. Passivation is not 100 percent effective, of course; the inactive DMSP-F11 satellite broke up on orbit despite undergoing the procedures, for example. But if it can reduce the chances of a debris-causing event, even if only by a small measure, that might make more sense than attempting to squeeze additional but marginal utility from a satellite that is almost 10 years past its prime.