LEO Boom Raises Orbital Debris Concerns

Already an issue after China's 2007 test of an anti-satellite missile system and the 2009 collision between Iridium and Russian Space Forces satellites, debris awareness is escalating, given the flood of small satellites and nanosatellites going up, said Brian Weeden, technical adviser for Secure World Foundation. While the LEO boom "represents a huge amount of innovation and additional benefits, the question is how do we enable that while mitigating some of the challenges," he told us.

Debris is becoming a sticking point as SpaceX looks to put up test satellites in advance of its planned LEO constellation for a low-latency, worldwide, high-capacity Internet service. Intelsat has criticized the test satellite plans, saying SpaceX hasn't provided enough information to assure there are no collision risks (see 1507230020). Its constellation "has an especially low risk of collision," due to its orbit at a 625-kilometer altitude, where there are no other satellite systems, and the relatively low orbital lifespan of about nine years, SpaceX said in an orbital debris filing at the FCC. In a statement Thursday, Intelsat said it has "long been a vocal proponent of satellite operators sharing information with one another to avoid or mitigate any potential interference issues that could disrupt connectivity," saying it's "understandably concerned about any system that could potentially cause interference with the valuable services that we provide to our customers every day. It is helpful that SpaceX has provided additional technical information. We are continuing to review their submission to determine if it is adequate for us to complete a thorough analysis of the potential impact."

More than 650 LEO satellites are in orbit, slightly more than half of all the operational orbiting satellites, according to the Union of Concerned Scientists' Satellite Database, and that number is expected to grow quickly with OneWeb alone planning a LEO constellation that would nearly double that (see 1506250023). Alongside those satellites are 22,000 "pieces of junk" larger than 10 centimeters that are tracked regularly, as well as an estimated 300,000 to 500,000 smaller pieces of debris not tracked regularly, Weeden said. "There are a lot of objects up there," and six to seven times a year Globalstar has to do maneuvers to keep one of its satellites at a safe distance from some other object, Aries Broadnax, Globalstar satellite operations director, told us.

Not everyone sees cause for concern, at least from LEO nanosatellite traffic. "People are talking about satellites as if a satellite is a satellite is a satellite," said Peter Platzer, CEO of Spire, which plans to have 125 LEO satellites up by 2017. "Some are a mosquito and some are an elephant." Instead of the numbers of satellites, far more important metrics are surface area and mass of satellites and their time in orbit, Platzer said. "Collision risk is a function of surface area and time in orbit, and collision damage is a function of mass," he told us. "This is what matters for space debris." While space debris in general is a concern, the biggest worries are large satellites and rockets, which account for 99 percent of the orbital debris in terms of surface area or mass, he said. Spire's satellites each will be about the size of a wine bottle and weigh a few pounds, with orbital life of seven to eight years, Platzer said.

The FCC last updated its rules on orbital debris in 2004, when it said any satellite operator seeking agency space station authorization or anyone wanting an agency ruling for access to a non-U.S.-licensed space station is required to submit an orbital debris mitigation plan in connection with satellite design and operation. Before that, the agency had debris mitigation rules only for certain classes of satellites, such as mobile satellite service operating in the 2 GHz band and for Ku- and Ka-band nongeostationary orbit fixed satellite service. The National Oceanic and Atmospheric Administration also requires a debris mitigation plan for its licensing of remote sensing satellites.

Orbital debris rules may be changing, however. The Spurring Private Aerospace Competitiveness and Entrepreneurship (Space) Act of 2015, passed by the House in May, would direct NASA to arrange with an independent, nonprofit, private systems engineering and technical assistance organization to study frameworks for the management of space traffic and orbital activities.

LEO satellites typically are decommissioned by re-entering the atmosphere and burning up, usually after at most 15 years, while geostationary satellites end up in a higher orbit, out of the way of satellite operations. After roughly nine years, SpaceX's MicroSat satellites are expected to re-enter the atmosphere and burn up, due to their small mass -- about 128 pounds -- and largely aluminum construction, it said. PlanetIQ, using additional fuel on board, plans to de-orbit its satellites within a year of their retirement. "We are mindful of the growing threat of orbital debris and strive to be good stewards of space," spokesman Dan Stillman said.