“SIMPLICATE PLACE, these tests are dangerous and we will not perform them.” So said Kamala Harris, Vice President of America, in an April 18 speech at Vandenberg Air Force Base in California. Harris was announcing an American ban on complete testing of “direct ascension anti-satellite missiles” – ground-launched weapons designed to blow up satellites in orbit.
Four countries – the United States, China, India and Russia – have carried out these tests, most recently Russia in November last year. The danger Harris fears is not so much from the weapons themselves, but from the mess they create. Space is already full of junk: empty rocket stages, paint smears, nuts and bolts, toothbrushes dropped by careless astronauts, and the like. It can stay in the air for decades. At orbital speeds, even small items can do damage. The International Space Station (ISS) has to avoid pieces of garbage about once a year. In June 2021, debris tore a jagged hole in one of its robotic arms.
Anti-satellite missiles, designed to blow satellites to smithereens, make the problem much worse. A typical test can generate more than 100,000 pieces of debris, says Marlon Sorge of Aerospace Corporation, a California-based nonprofit. Harris noted that after a Chinese test conducted in 2007, more than 2,500 pieces of debris large enough to track remain in orbit. There will be an unknown but much larger number of smaller bits.
Meanwhile, the number of satellites in orbit is rapidly increasing. SpaceX, an American company, is allowed to launch around 12,000 satellites for its Starlink orbital internet service, more than has been launched since the start of the Space Age in 1957. Other companies, such as Planet and Maxar, which provide orbital imagery, manage fleets of their own. Armies rely on satellites for communication, weather forecasting, and even to provide early warning in the event of a nuclear attack.
At worst, a combination of more clutter and more things to get right can start a slow-motion chain reaction, in which each collision produces more debris, making future collisions more likely. This Kessler syndrome – named after the NASA scientist who first modeled the phenomenon in 1978 – could leave important orbits unusable for decades.
Since that would be bad for everyone, Harris hopes other countries will copy American policy. Perhaps. The timing of the initiative is not auspicious, to say the least. In addition to $2.5 billion in arms shipments, the United States is believed to be providing intelligence, including from satellites, to Ukraine’s army to help the country fight the Russian invasion. Russian officials have complained about SpaceX satellite terminal shipments to Ukraine’s armed forces.
And while space junk is bad for everyone, it’s worse for some than others. More than half of all active satellites are American, meaning other countries would have less to lose if parts of Earth’s orbit became too dangerous to use.
But there are also reasons for optimism. The United States’ self-imposed ban is only on “destructive” missile tests, so nations that followed suit would not have to give up their orbital weaponry altogether. Other methods of disabling satellites are being investigated, from blinding or blocking them to grabbing them with other satellites. And, says Robin Dickey, another analyst at the Aerospace Corporation, Harris’ speech appears to be more focused on building “norms of responsible behavior” than on formal gun control agreements – leaving other countries free to adopt bans without international pressure.
Such norms, it seems, already have power. Countries that carry out anti-satellite tests are clearly defensive towards them. The United States justified one in 2008 on the dubious grounds that the target satellite, which was out of control, contained hundreds of pounds of dangerous rocket fuel. After an Indian test in 2019, the country’s Foreign Ministry claimed that by deliberately choosing a target in a relatively low orbit, the resulting debris would “decay and fall back to Earth within weeks”. The battle, in other words, may already be half won. ■
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This article appeared in the Science and Technology section of the print edition under the title “Release range”