Carson Bullock* and Robert T. Johanson
Edited by Thomas G. Roberts and Friederike M. C. Benning
Article | Aug. 30, 2021
- Advances in tracking have clarified the risk orbital debris proliferation poses to satellites, but no system for risk assessment of individual space objects has yet been universally accepted. Consensus has been reached about a few broad classes of space objects that are high-priority targets for removal.
- Progress has been made in slowing the creation of new debris, but it is likely insufficient to ensure safe scientific and commercial activity in space without also removing existing debris. Several methods of active debris removal have been demonstrated and more are on the horizon, but how they will be funded, how to incentivize their use, and the legal regime around their deployment remains uncertain.
- Changes to federal policy can incentivize responsible behavior through a variety of mechanisms, each with benefits and drawbacks.
Space debris threatens to destroy valuable space infrastructure, but damages from debris are not an inevitability. The scientific community has ideas for how to prevent the creation of new debris and limit the impact of pre-existing debris, but it will take government action to see that vision through. This essay unpacks how we know what we know, in service of ultimately discussing how policy-makers can use predictions of the long-term risks posed by satellites and debris on the orbital environment to more effectively prescribe behavior for operators. Financial incentives for sustainability, including taxation and cap-and-trade systems, have the potential to greatly benefit the safety and reliability of space missions, but they carry a variety of political and economic challenges, particularly at the international level. Now is a critical time to determine a policy strategy for debris management, because negotiations in the near-term may set valuable precedents for controlling the next century of debris proliferation.
Kosmos-2251 is ready for liftoff. It is June 16, 1993, and 2251 is strapped atop a Kosmos-3M rocket, sitting on the pad at the Plesetsk Cosmodrome in Russia. The Strela-class communication satellite and its rocket have decades of heritage, so it is no surprise that the launch goes off without a hitch. Placed into a nearly circular orbit 500 miles above the Earth’s surface, 2251 can expect years of operation followed by decades more in retirement. Kosmos-3M’s first stage immediately falls back to Earth, and the second stage, a 1.4-ton solitary rocket body that travels nearly to 2251’s final orbit, is left drifting . Only a couple years later, the satellite shuts down early. From then on, 2251 whips around the Earth day in and day out, ignorant to the steady launch of new satellites. Until in 2009, when 2251 smashed into another satellite. Had 2251 been working, operators on the ground may have seen the impending disaster and ordered a quick maneuver. As it happened, Iridium 33 did not see 2251 either, and the two satellites were obliterated. At 22 000 mph, the collision flung thousands of pieces of debris throughout Low Earth Orbit (LEO). These pieces silently circle the Earth and will for decades to come, until some other satellite like Iridium 33 crosses their path or until someone becomes willing to pay a hefty price and use cutting-edge technology to try to remove them. The International Space Station maneuvered away from a piece of Iridium 33 debris in 2012 and was struck by a piece of debris of unknown origin in June 2021 [2, 3].
The Kosmos-Iridium collision was a wake-up call for the space industry. If Iridium’s loss of an operating spacecraft was not enough, that single event increased the cataloged objects in LEO by roughly 12%, as shown in Fig. 1 . Today, the number of catalogued pieces of debris is more than double the number of spacecraft in orbit . This figure includes rocket bodies and large fragments of destroyed spacecraft, but excludes objects like tools dropped by astronauts and paint chips, because they are too small to be tracked. At orbital speeds, even the smallest of these wandering missiles can cause crippling damage.
Incentivizing Sustainability Through Policy
The authors would like to thank MIT for the opportunity to work on these complex, interesting problems and to the Review’s editorial team for their support developing the ideas in this article.