A spacecraft launched by NASA is attempting to rescue an ageing space observatory whose orbit has been lowered by solar activity, putting it at risk of re-entering Earth's atmosphere as early as this year.

The mission centres on the Neil Gehrels Swift Observatory, which was launched in 2004 to study gamma-ray bursts. Recent solar storms have reduced the observatory's orbital altitude, leaving it in danger of burning up in the atmosphere unless its orbit is raised.

To extend the telescope's operational life, NASA enlisted Katalyst Space Technologies to carry out an orbital servicing mission. The company's Link spacecraft launched on June 3 and is expected to rendezvous with Swift before raising its orbit by approximately 150 miles.

Swift is currently orbiting Earth at an altitude of about 224 miles. Unlike many satellites, it has no onboard propulsion system, requiring an external spacecraft to adjust its orbit.

NASA said the mission was completed under an accelerated timetable because Swift's orbit was expected to decay beyond recovery by October. Katalyst developed and launched the mission in nine months at a cost of approximately $30 million. The Swift Observatory, by comparison, is valued at around $500 million.