Space weather Spaceflight's biggest danger

The Hayabusa mission was almost destroyed by one of the most hazardous events a spacecraft can experience – a solar storm.Hayley Smith looks back at the mission

- Hayley Smith looks back at the mission

It was 15 years ago this month, on 13 June 2010, that the world watched as a beleaguered traveller finally arrived home, after a long and perilous journey back to land. The trouble began in 2003, as All Hallows' Eve approached. All seemed calm as the vessel Hayabusa (Japanese for mighty falcon) sailed through the darkness towards uncharted shores. Unbeknown to the crew, though, the ship was about to be hit by one of the fiercest storms in recorded history.

This could be an account from a 15th-century ship's log, but it is in fact a tale of the Space Age. Hayabusa was a robotic spacecraft sailing through interplanetary space on a two-year journey to rendezvous with asteroid 25143 Itokawa when it was battered by a series of massive eruptions unleashed by the Sun. The 'crew' in this case was the ground team, watching helplessly from the safety of their vantage point in mission control back on Earth.

Hayabusa, operated by the Japan Aerospace Exploration Agency (JAXA), planned to learn about Itokawa by studying its history, shape, composition and topography, providing a wealth of data for scientists on the ground to learn from. In a daring grand finale, the spacecraft was to attempt the first-ever controlled landing on an asteroid, collecting a sample of material from the surface to return to Earth for further study. It also carried a small rover named MINERVA (Micro-Nano Experimental Robot Vehicle for Asteroid), designed to hop across the surface collecting data.

All appeared to be going to plan until the ship was caught in inclement weather, as so many of its terrestrial counterparts have been before it. In this case, the weather was 'space weather', a barrage of charged particles and electromagnetic radiation driven by the volatile moods of the Sun.

Perils of the solar wind