When we last left Apollo 17, they had just set off on their long, two and a half day coast to the Moon. Astronauts Gene Cernan, Ron Evans, and Jack Schmitt – the 6th (Cernan, having previously gone on Apollo 10), 23rd, and 24th men to ever make the voyage – had an uneventful Earth-Moon transit and completed check-outs of their Lunar Module (LM) Challenger, conducted some scientific experiments on board their Command/Service Module (CSM) America, and finally on Flight Day 4 (December 10, 1972) reach the Moon and enter lunar orbit.
Here is a summary of major flight activities, times in Ground Elapsed Time (GET) unless otherwise noted:
35:20:02 – The crew completed a quick, two second burn of the CSM’s Service Propulsion System (SPS) engine to refine their trajectory towards the Moon. America and Challenger are now more precisely aimed at their target.
40:10:00 to 42:11:00 – Commander (CDR) Cernan and Lunar Module Pilot (LMP) Schmitt boarded LM Challenger for two hours of housekeeping and communications check out tasks.
47:27:00 – (12:00AM EST 12/9/72) – Flight day 2 ends.
59:59:00 to 62:16:00 – Cernan and Schmitt execute another two-hour stint of LM preparations aboard Challenger.
65:00:00 – 2 hours, 40 minutes added to the mission timer to reflect the launch delay. Apollo 17’s trajectory was accelerated and the time added so that the original flight plans would be valid.
73:17:45 (11:10PM EST 12/9/72) – Apollo 17 passes equigravisphere – the point at which the gravitational influence of the Earth and Moon are the same. America and Challenger have been slowing down since Trans-Lunar Injection (TLI) on December 7th as the Earth’s gravity tried to pull the spacecrafts back. Now that the Moon’s gravity is dominant, Apollo 17 will be gaining speed until time for Lunar Orbit Insertion (LOI).
74:07:00 (12:00AM EST 12/10/1972) – Flight day 3 ends.
84:12:40 – Command Module Pilot (CMP) Ron Evans jettisons the door covering the Service Module’s Scientific Instrumentation Module (SIM) bay in preparation to beginning the mission’s lunar science program at 83:26:00.
87:30:00 – Apollo 17 passes into lunar shadow and begins ultraviolet photography of our Moon.
88:43:00 – America and Challenger have passed behind the Moon and are now out of communication with Earth. The crew are making final preparations for their LOI burn.
88:54:23 – the six and a half minute LOI burn begins. The SPS engine fires to allow the Moon’s gravity to capture Apollo 17 into lunar orbit.
89:00:26 (2:53PM EST 12/10/1972) – Lunar orbit! Apollo 17 has arrived after a successful LOI, but Earth doesn’t know it yet as they’re still behind the Moon.
89:16:00 – Mission Control in Houston regains communications with the crew and learn of the near perfect LOI.
89:39 (approximate) – the S-IVB third stage from Apollo 17’s Saturn V impacts the Moon as an experiment for the seismometers left behind by previous Apollo astronauts at their landing sites.
93:11:37 – Cernan, Evans, and Schmitt light up America‘s SPS engine one more time to put the combined spacecraft into the proper descent orbit (maneuver known as Descent Orbit Insertion 1, “DOI-1”) for the future departure of Challenger carrying Cernan and Evans to the lunar surface. DOI-1 is successful after a 23 second burn.
98:07:00 (12:00AM EST 12/11/1972) – Flight day 4 ends.
Return tomorrow for the events culminating in the sixth manned lunar landing and the first of three lunar EVAs by Cernan and Schmitt!