India became the fourth country in the world to demonstrate the ability to destroy a satellite in Earth orbit with a ground-based missile today. Indian Prime Minister Narendra Modi personally made the announcement via television. USAF Lt. Gen. David D. Thompson, Vice Commander of U.S. Air Force Space Command, confirmed the test during an appearance before a Senate committee this afternoon and said the Air Force has identified 270 pieces of space debris so far.

A number of methods are available to destroy, disable or disrupt satellite systems, but the type that most readily leaps to mind is what India tested today, a direct ascent kinetic kill vehicle where a rocket is launched from Earth and intentionally collides with a satellite.

The United States, Soviet Union and China have tested such weapons so far, making India the fourth country to demonstrate an ASAT capability. The tests have been against each country’s own spacecraft. No laws or treaties prohibit testing or deployment of this type of ASAT system.

The result, however, is not only destruction of the satellite, but creation of space debris that can imperil other satellites for years to come. A Chinese ASAT test in 2007 created an initial cloud of 3,000 pieces of debris that continues to grow as pieces collide with each other, generating more debris. The Chinese government is widely criticized for that test, which destroyed an old Chinese weather satellite at an altitude of approximately 865 kilometers (540 miles). Eventually the debris will reenter Earth’s atmosphere and burn up, but it will take decades from that altitude.

India conducted its test against an Indian satellite in a relatively low Earth orbit where the debris should reenter relatively quickly. Modi said it was “almost 300 kilometers” (185 miles).

Testifying before a Senate Armed Services subcommittee this afternoon on military space programs, Thompson pointed out that the test was below the altitude of the International Space Station (ISS) so the debris does not pose any hazard to it. ISS orbits at about 350 kilometers (220 miles).

Thompson said the Air Force knew the test was coming based on public information from India, detected it as soon as it launched, and immediately began collecting information about the debris field. It is publicly providing notice about the objects on its Space Track website and will notify satellite operators if any piece poses a risk, as it already does with other space objects. “Currently they are tracking about 270 different objects…. Likely that number is going to grow as the debris field spreads out and we get more sensor information.”

Modi proclaimed the test, designated Mission Shakti, “a remarkable success. India has today established itself as a global space power.” He added that he wanted to “assure the international community” that this capability is “not directed against anyone. India has no intention to threaten anyone” and remains “opposed to the weaponisation of space and an arms race in outer space, and this test does not in any way change this position”

A fact sheet from India’s Ministry of Foreign Affairs said the test was done to “verify that India has the capability to safeguard our space assets.”

Modi said the test used a ballistic missile defense interceptor launched from Dr. A P J Abdul Kalam Island. Amateur satellite trackers used that and other information to identify the target satellite, Microsat-r, which India launched in January and was said to be a military earth observation satellite. Marco Langbroek (@Marco_Langbroek) summarized analysis by himself, T. S Kelso (@TSKelso), and @Dutchspace in a blog post. He agrees that most of the debris should reenter “within weeks,” but a few pieces could be “ejected into higher orbits.”

Another entrant into the club of countries conducting ASAT tests is troubling to those who want to prevent an arms race in space as well as those interested in space sustainability — ensuring space remains a usable environment for future generations. Planet, a company deploying a large constellation of small remote sensing satellites, reacted to the test in a tweet.

Planet’s response to India’s testing of an anti-satellite missile. pic.twitter.com/bZuuIYtCFB — Planet (@planetlabs) March 27, 2019

Preventing satellites from performing their functions is called “counterspace” and involves everything from direct ascent ASATs to cyberattacks. Last year the Secure World Foundation (SWF) and the Center for Strategic and International Studies each published reports summarizing global counterspace capabilities. The SWF report includes historical and current U.S. activities. The Defense Intelligence Agency recently published a report on Challenges to Security in Space, though much of the information is dated.