Hinode spacecraft: near encounters with space debris

The life of a spacecraft can be a difficult one. It’s made even more challenging with the amount of space debris that exists. The debris comes from a range of sources – mainly old satellites and rocket stages.

Using radar techniques the debris is monitored, with over 22,000 pieces that are bigger than 10 cm wide currently being tracked.

There are probably millions of bits smaller than this that can also cause damage.

Hinode was launched in 2006, and had previously made one spacecraft manoeuvre to avoid debris. This was back in March 2012.

This debris-avoidance manoeuvre (known as a DAM) involved changing the orbit of the spacecraft by using the thrusters. The instruments onboard were put into a safe mode and stopped operating during this time.

In January 2015, preparations were made for a possible DAM on 19 January, but as the time approached it was possible to cancel the DAM as the collision probability became low enough as the orbit prediction was revised.

On 26 January another piece of debris was deemed to have a high risk of collision and the DAM was set into motion. The instruments were put into safe mode and stopped operating over the weekend. The spacecraft did not have to carry out the manoeuvre in the end, and after the close encounter the spacecraft was safe and is in its usual orbit.

The instruments will start operating normally once again on 29 January.

Space debris is an ongoing and increasing problem, and no doubt more of these alerts will be coming in future.

• Louise Harra is Professor of Solar Physics at UCL, and is the UK scientific leader on the Hinode Extreme Ultraviolet Imaging Spectrograph, part of the Japanese/US/UK Hinode spacecraft