One week after India became the fourth country in the world to target and shatter a satellite in low Earth orbit with a missile, NASA Administrator Jim Bridenstine condemned the unilateral move on Monday.

During a town hall meeting, Bridenstine called the test “unacceptable,” saying, “Intentionally creating orbital debris fields is not compatible with human space flight.” According to a NASA assessment last week, the Indian space test increased the likelihood of small debris hitting the International Space Station (ISS) by 44 percent over a period of 10 days. The risk is expected to eventually return to normal. Debris impact can have catastrophic repercussions in space, which is why NASA tries to track the trajectory of potentially dangerous pieces.

“What we’re tracking right now — objects big enough to track, we’re talking about 10 centimeters or bigger — about 60 pieces have been tracked,” said Bridenstine, referring to the fallout of the Indian space test. The antisatellite test catapulted 24 of those pieces to locations above the ISS, from where they will gradually descend toward Earth, possibly passing the space station. Other debris pieces have been identified but not yet tracked, which means that they could collide with the ISS without prior warning.

During the three-minute-long antisatellite test last week, India shot down one of its own satellites to prove that it has acquired technology that would allow it to participate in possible future confrontations in space. While the vast majority of global defense budgets are still used to purchase conventional arms, experts are warning that space is increasingly becoming a new frontier for some of the world’s best-equipped militaries. President Trump announced the creation of a U.S. Space Force last June, and China, India and other nations are also doubling down on defense-related space ambitions.

“We are not just capable to defend on land, water and air, but now also in space,” Indian Prime Minister Narendra Modi said last week. “India registered its name as a space power,” he said.

The Indian Foreign Ministry initially defended its antisatellite test last week, saying in a statement: “Whatever debris that is generated will decay and fall back onto the earth within weeks.” It did not, however, acknowledge that some debris may pose a threat to the ISS on its path back to Earth.

The satellite destroyed by India last week was 186 miles from Earth, whereas the ISS usually circles Earth at an altitude of at least 205 miles. But last week’s missile attack sent some debris parts far deeper into space.

The Indian test’s risks still fade in comparison with the 2007 equivalent by its archrival, China, which shattered a satellite at an altitude of more than 500 miles. The 2007 test is estimated to have created about 25 percent of today’s debris larger than 10 centimeters. At the time, Beijing was widely condemned for targeting one of its own satellites in a densely used orbit, where the likelihood of a catastrophic crash is highest.

Even though China has refrained from repeating its 2007 test, it continues to pursue its controversial antisatellite program. Experts fear that an arms race in space could ensue as a result, and last week’s Indian test offered the strongest evidence for that so far.

While the European Space Agency estimates that about 34,000 debris parts larger than 10 centimeters are circling in orbit, NASA monitors only 10,000, so far. When those objects collide with one another, they create even more — and potentially still dangerous — debris.

Meanwhile, programs to clean up space have stalled. “There are no salvage laws in space. Even if we had the political will to [salvage junk], which I don’t think we do, we couldn’t bring down the big pieces because we don’t own them,” Joan Johnson-Freese, a Naval War College professor, told The Washington Post in 2014.

Some have suggested constructing smaller satellites that could orbit at lower altitudes and escape the potentially deadly debris cloud above. Last week’s Indian test, however, showed that there are no safe spaces anymore, even closer to Earth.

Indian rival Pakistan issued a stern warning to India following last week’s test, with the Foreign Ministry writing in a statement: “Every nation has the responsibility to avoid actions which can lead to the militarization of this arena.”

NASA Administrator Bridenstine echoed those words of caution on Monday, saying, “When one country does it, then other countries feel like they have to do it as well.”

The world’s first antisatellite missile test did not originate in China or India, however, but in the United States, in 1958.

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