One of the SRB nozzles on STS-9 had been applied with the same flawed insulation material, that had nearly burned through during Challenger's mission in August 1983. A replacement was ordered and the launch of STS-9 had to be delayed until November 28, 1983.
STS-9 had originally targeted a September launch date, but already had to be pushed into October, because the TDRS-A data-relay satellite - which was essential for the Spacelab mission - had not been operational in time. Originally even the second TDRS should have been launched on STS-8, but technical troubles with the IUS during STS-6 in April had prevented that.
With STS-9 moving into late November/early December 1983, planned earth observation tasks from Columbia's high inclination orbit (57 degrees) would now suffer from reduced lighting in the northern hemisphere.