The question came up recently: What happens if the ATV’s ride into space on board Ariane 5 is delayed for any reason? How does this affect arrival at the ISS? Most importantly, how does this affect the launch of Space Shuttle Discovery, now planned for 24 February? Now that we have, in fact, a delay, we posed this question to ESA’s Bob Chesson, Head of the Human Spaceflight Operations department.
He said that a delay in ATV launch of up to a maximum of 3 days will cause a day-for-day delay in ATV docking. ATV needs eight days to get up to Station. Therefore, as of today, the Johannes Kepler docking foreseen for 23 February has been replanned for 24 February, at 15:45 UT.
The effect on the Shuttle launch is similar: NASA have made the decision that any delay in ATV launch (and therefore docking) during 15-18 February will entail a day-for-day slip in the launch of Discovery from 24 to 27 February. This is because flight rules require that ATV must be docked to the ISS before the Shuttle launches.
If ATV launch is delayed beyond 18 February, NASA will probably launch the Shuttle on 24 February and slip the ATV docking until after the Shuttle has left the ISS. We have identified March 9 as a docking opportunity in this case.
Bob emphasized that this situation is very dynamic and may change quickly – and, of course, depends on a number of final decisions to be made by the ISS partners.