The Link spacecraft, owned by defense technology company Katalyst Space Technologies, departed from the Marshall Islands to rescue NASA's Swift Observatory, which is in orbit and at risk of falling.
Link, which will intervene with the telescope descending faster than expected due to solar storms, is expected to reach its target in about a month.
According to NASA's plan, Link will capture Swift, launched in 2004, in its orbit, fire its thrusters and lift the telescope 240 kilometers higher than its current position.
Weighing 1.4 tons, Swift is currently 360 kilometers above Earth. Observations were suspended to preserve the telescope's orbit as long as possible; it is estimated that it could resume operations by September.