Archive for May 16, 2019

05/16/2019 – Ephemeris – Looking back at the Ranger program: Getting really close up pictures of the Moon

May 16, 2019 Comments off

Ephemeris for Thursday, May 16th. Today the Sun will be up for 14 hours and 51 minutes, setting at 9:05, and it will rise tomorrow at 6:12. The Moon, 2 days before full, will set at 5:51 tomorrow morning.

The reconnaissance missions that had to be accomplished before the United Stated could land on the Moon in 1969 started with the Ranger program. The idea was to send a spacecraft to crash on the Moon taking and transmitting television pictures all the way down. In addition to the camera some Ranger spacecraft had a lunar capsule with a seismometer with a retro rocket to slow that package down and survive the landing. That feature never worked. Nine Rangers were launched. Only the last three were successful in returning images. Each returned thousands of images each returning detail down to 20 inches. One surprise, the rays we see from craters like Copernicus are actually chains of craterlets caused by ejecta from the impact.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.


Here’s a time lapse video of Ranger 9 hitting the crater Alphonsus. 17 minutes collapsed into 13 seconds: