On April 3, ESA’s Sentinel-1A environmental monitoring satellite launched from the Kourou spaceflight center in French Guiana.  Just when the mission team was relaxing after the rigors of getting their spacecraft in orbit, solar arrays safely deployed, this happened, as reported a few days later on ESA’s blog….

The alert
At the end of the first day after the launch (4 April): all deployments have been executed during the night and completed early in the morning at the beginning of the first ‘day shift’. As the first day shift nears its end, a serious alert is received: there is a danger of a collision with a NASA satellite that can no longer be manoeuvred. Not much information at the beginning, we are waiting for more information, but a collision avoidance manoeuvre may be needed.  ‘Are you kidding? A collision avoidance manoeuvre during LEOP [Launch and Early Orbit Phase]? This has never been done before, this has not been simulated!’

The satellite has not yet reached its ‘normal pointing mode’, we cannot manoeuvre it before this is reached. There is no alternative. After a brief team consultation Juan, the ‘day shift’ Deputy Flight Operation Director,  decides to start preparing the satellite in case a manoeuvre is needed, and to be executed by his colleagues on the night shift.

The safest hands

The night shift starts at 21:00 on 4 April. Hand-over between Juan and Pier-Paolo’s teams. More precise information comes in: the risk of collision is significant, there are two possible occurrences, at 09:43  and at 11:21 on the following morning. Distance: 20 m! This is serious. No Hollywood fiction, this is Gravity  for real!

Continue reading the account on ESA’s blog