NASA has launched an unprecedented robotic mission to save one of its most scientifically valuable space observatories from burning up in Earth's atmosphere. A three-armed spacecraft called LINK, built by US-based start-up Katalyst Space Technologies and launched by Northrop Grumman, blasted off on Friday from an atoll in the Marshall Islands in the central Pacific Ocean, carried aloft by a Pegasus XL rocket released from the belly of a modified aircraft. LINK is now on course to intercept NASA's Swift Observatory in approximately one month.

Swift, which is roughly the size of a large car and weighs 1.6 tonnes, was launched in 2004 to study gamma-ray bursts — the most powerful explosions in the universe, caused by the violent deaths of massive stars and the collisions of their remnants. These events release as much energy in seconds as the Sun will emit over its entire ten-billion-year lifetime. Because the bursts are fleeting, Swift was designed to react quickly, making it uniquely capable and difficult to replace. The telescope was originally positioned at an altitude of around 600 kilometres, but increased solar activity over the past two years has expanded Earth's upper atmosphere, creating drag that has steadily pulled Swift down to roughly 360 kilometres. Without intervention, NASA predicts it will re-enter the atmosphere and be destroyed as early as October.

The $30 million rescue operation — assembled in just nine months — involves a sequence of steps never before attempted in orbit. Once LINK powers up its systems and confirms its instruments survived launch, it will spend several weeks manoeuvring alongside the moving telescope. It will then circle Swift, photographing it from every angle before deploying its three robotic arms to dock with a spacecraft that was never designed to be captured. Engineers acknowledge uncertainty about how Swift's exterior has changed after two decades in space. If the docking succeeds, LINK will use small thrusters to raise Swift's orbit gradually and gently — by approximately 240 kilometres — over the course of two to three months, returning it close to its original altitude.