&Cartridge; physics 14, 113
Scientists should press for global rules for launching commercial satellites that pose hazards in space and could hamper astrophysical observations.
Like many space researchers, I’m excited about the “New Space” wave that is currently sweeping through robotic space exploration. This wave includes the launch into space of a rapidly growing number of small but very powerful spacecraft, or “smallsats”. Many smallsats are used for scientific purposes – solar, magnetospheric, and ionospheric studies, remote Earth sensing, and astrophysical observations – and they hold promise for quickly gathering useful information about the Earth’s cosmos and environment.
But New Space has another side. Along with the dozen of small scientific satellites launched each year, thousands – possibly tens of thousands – of commercial satellites are being prepared for launch, most of which are also small (weighing less than
). The proliferation of these satellites poses significant risks to space systems and science, as they could generate dangerous space debris and interfere with astronomical observations. I believe that satellite launches should be restricted on such a large scale until the space community fully understands the problems these satellites pose and enacts regulations that prevent or mitigate these problems.
Most of the proposed small commercial satellites will orbit our planet in low earth orbit (LEO) – at altitudes less than 2,000 km – and provide communication capabilities. Improving point-to-point communication for people around the world is an important goal. But when the earth is enclosed in a cocoon of small spaceships, the risks are enormous.
First, tens of thousands of new objects in LEO mean that there would be more “stuff” that other “stuff” must avoid: a spacecraft crashing into another orbiting object could trigger a cascade of collisions that could create volume of debris a million times larger than that of the two originally colliding objects. It is already a challenge to keep track of both the currently operational spacecraft in LEO and the thousands and thousands of space junk from abandoned spacecraft and missile bodies. Adding to this problem makes no sense.
Second, the relocation of so many spacecraft in LEO is a threat to the safe launch of other satellites into higher orbits. Most space researchers believe that we need more scientific “eyes in the sky” on the mean earth orbit (approx. 2000–30,000 km altitude) and on a geostationary earth orbit (approx. 36,000 km). If LEO gets too crowded, it may become impossible to safely launch missiles to these higher observation sites. It is also of vital importance that manned or robotic vehicles can safely pass LEO on their return to Earth. We cannot allow an impenetrable barrier to form around our planet.
After all, a huge swarm of tiny satellites could interfere with astronomers’ ability to observe the cosmos from the surface of the earth (see Drawing a Line in the Sky: Astronomers Confront the Threat from Satellites). No matter how carefully designed, each satellite reflects sunlight and blocks the transmission of light from distant astronomical objects. A huge cloud of small spacecraft can distort the view of the night sky (or even the daytime sky!) And make ground-based astronomy nearly impossible, which would have tragic implications for key areas of science.
For all of these reasons, governments and the entire space community must act decisively to establish policies and guidelines for the launch, operation and disposal of vehicles. The current space debris is already a major problem, as the National Orbital Debris Research and Development Plan – a report commissioned by the US National Science and Technology Council – emphasizes. The unimpeded deployment of thousands of additional small commercial satellites could make it impossible to mitigate such problems. Effective guidelines should require clear and tightly controlled plans for each newly launched satellite: Anything put into orbit must be promptly and safely removed from orbit upon completion of its mission.
In my view, the satellite overpopulation problem in near-earth space is a global problem that cannot be addressed by just one nation – for example, if the United States stopped small satellite launches, private companies would look elsewhere for launch opportunities. But every space country today, and every country it aspires to become, should be extremely concerned about an emerging “tragedy of the commons” on our planet. This situation will only get worse if we don’t do something right away and with a real purpose. Therefore, I encourage space scientists of all stripes to lobby their governments and all relevant agencies to declare an immediate pause on massive constellations of smallsats until a thorough, enforceable, sustainable and enlightened set of guidelines is in place.