Space Debris and Mt. Everest

With the proliferation of satellites going to orbit of late, I’m often asked what lies ahead with respect to the issue of debris in space. By many accounts, thousands of new satellites will be in Low-Earth Orbit (LEO) by 2025. These will be joining the hundreds of thousands of pieces of space debris already in orbit.

One possible future outcome lies more than 7,000 miles due east of my office in Cambridge, Massachusetts, and then about 5.5 miles straight up. If we want to predict the future of LEO, consider the history of Mount Everest.

Like LEO, Mount Everest was once beyond our reach. Sir Edmund Hillary and Tenzing Norgay were the first to summit Mount Everest in 1953. Things very quickly got messy. In just over five decades, however, the first dedicated mission to clean up the garbage on Everest was underway.

Is there anywhere our species can go without leaving a mess? If we’re going to sort that out with respect to space debris, the time is now.

Only 60 satellites launched during the first nine years of space exploration. It’s about to get much more crowded up there. The SpaceX Starlink constellation aims to launch 12,000 small satellites by 2027. Of the first 60 SpaceX satellites that were launched earlier this year, five percent of them are no longer responding to demands and appear to be “dead.” If that trend continues, 600 of the planned 12,000 Starlink satellites will be floating space junk in a few years. Add in constellations of over 1,000 satellites planned by OneWeb and Amazon plus dozens of companies preparing smaller constellations and the magnitude of the problem will continue to get worse. LEO is expansive, but it’s not infinite.

If satellite operators don’t de-orbit or move into graveyard orbits, the risk of the Kessler Syndrome only increases. Proposed by NASA’s Donald J. Kessler in 1978, the Kessler Syndrome is a cascade of collisions created by space debris creating more space debris — all as a result of growing density of objects in LEO. Cinematically, check out the opening scene of the film Gravity for a dramatization of Kessler. Catastrophic collisions have already taken place and NASA predicts a one hundred percent likelihood of future Kessler scenarios. It’s only a question of whether the collision will be with large Hall thruster-based satellites whose tanks will create huge debris fields or with smallsats wherein the debris field will be smaller, but with increased frequency.

International guidelines call for de-orbiting satellites within 25 years of the end of their missions. Satellites in LEO are to lower their altitude to the point where Earth’s gravity takes over and burns up the satellites during descent. Geostationary satellites are to move hundreds of kilometers higher into graveyard orbits. To date, however, The European Space Agency (ESA) reports only 60 percent compliance. A recent NASA report stated that unless 99 percent of future satellites de-orbit once their missions are complete, then we are going to have a big problem with debris as well as a corresponding increase in perilous Kessler Syndrome scenarios (ESA’s recommendation was 95 percent de-orbiting.)

While anyone who has ever camped knows the rule of pack it in, pack it out, this idea is relatively new ground for the satellite industry. In our case, it means mandatory planned de-orbiting; guidelines are helpful, but they aren’t regulations. NASA, ESA, and other agencies need to give these guidelines some teeth if they’re going to be effective. The bottom line is this: if you’re going to send something up into space, following guidelines can’t be considered optional. Be sure you know how and when it’s going to come back. This isn’t an imminent problem; it’s already happening and only gets worse with every new launch.

Even if the vast majority of satellite operators start following the 25-year rule, a more hands-on approach to debris mitigation might become necessary. ESA says that in some orbits with heavy traffic, the international community might need to remove five to ten large objects annually to keep the debris population from becoming too dense. In fact, ESA has reported that “a ‘business as usual’ scenario will lead to a progressive, uncontrolled increase of object numbers in LEO, with collisions becoming the primary debris source.”

Companies and universities are preparing to test various approaches to retrieving the junk. The Surrey Space Centre’s RemoveDEBRIS satellite, for example, is an approach using a giant net to capture inactive debris. RemoveDEBRIS is also equipped with a harpoon to spear objects and a drag sail. Once it captures debris, it will unfurl the drag sail to slow down RemoveDEBRIS and its target until they burn up in Earth’s atmosphere.

The U.S. Space Based Surveillance System (SBSS) program has so far launched satellites into LEO and Geostationary Orbit (GEO) to track debris. Similarly, a Canadian start-up called NorthStar is plans to deploy a 40-satellite constellation to track space debris.

Researchers in China have proposed the means to redirect space debris through the use of in-space lasers. The lasers would theoretically impact the trajectory of the debris and send it into descent.

These are well-meaning, but problematic approaches. First, there’s little financial incentive to remove space debris. Who will pay for the implementation of these proposed solutions? Second, we can’t wait any longer. The most effective solution in cleaning up this growing mess is to stop making more of it.

That amounts to 100 percent planned de-orbiting.

The technology already exists to accomplish this. Outfitting a satellite with in-space propulsion capabilities ensures that the spacecraft can be navigated to burn up safely in Earth’s atmosphere at end of mission. Until very recently, however, there were no propulsion options small enough to fit on the incredibly popular small and cube satellites. In fact, many have been launched without propulsion. The hope is that the orbit of these satellites would eventually decay to a point where the spacecraft would naturally burn up in the atmosphere, but that can’t always be counted on in a timely manner — especially for small pieces of debris. Fortunately, advances in technology and science have been providing new options for these satellites. Using recent advances in electronics fabrication and nanotechnology, we have introduced one of the smallest, most powerful propulsion systems to the market, which will ensure every satellite has the functionality to navigate in space, and eventually de-orbit.

Whatever the approach, something (or combination of things) must be done to protect Earth’s orbit from becoming as littered as Everest did. This year alone, climbers in Nepal have collected more than 11 tons of garbage. Still, the climbers keep coming to the “world’s highest garbage dump;” this year Nepal issued a record of permits to climbers.

Likewise, 2019 is on track to break satellite launch records. Meanwhile, just as garbage from the very first Everest summit is still on the mountain, the very first piece of space debris — the U.S. Vanguard 1 — is still in orbit. It’s up there somewhere, along with millions of other pieces of debris. Five decades later, it’s time to tackle the problem created by all the defunct satellites and spent rocket stages left in orbit. The longer we wait, the more intractable the problem becomes. Waiting is not an option.

If this topic is new to you, the ESA and NASA have initiatives under way to mitigate this growing concern. The ESA Clean Space Initiative and NASA’s Orbital Debris Program are both valuable sources of information. If you are already concerned, perhaps take a deeper dive at the upcoming International Orbital Debris Conference, the first of its kind this December in Texas. And if you are planning to launch a satellite into LEO, make sure you have a plan in place before you launch to bring that satellite out of LEO when your mission is complete. VS

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