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Contains: 
Apollo 15 Approach Trajectory, 





    
        

            Bruce Rohrlach

Apollo 15 Approach Trajectory

Technical card

Resolution: 14000x10105

Date:Nov. 17, 2018

Focal length: 7000

Seeing: 4

Transparency: 8

Locations: Boronia, Melbourne, Victoria, Australia

Data source: Backyard

Description

This annotated image (taken with a Skywatcher 8 inch /f5 Newtonian from home last weekend) shows the area along the front of the Apennine Range where David Scott and James Irwin flew and landed the Falcon Lunar Module (Apollo 15 mission) onto the lunar surface adjacent to Hadley Rille (whilst Al Worden Command Module pilot stayed in orbit). The approximate approach path to landing is illustrated by the white arrow, they came in from the east (north is to the left of the image) flying in low over the Apennines and between peaks on either side in the final stages of approach/descent.

Falcon made one of steepest descents onto the lunar surface of any of the Apollo missions, primarily because they had to fly just over the lip of the Apennines and then drop down steeply at the last minute to land near Hadley Rille. The Apennines on the edge of Mare Imbrium are similar in scale to the Andes (peaking at 5500m at Mons Huygens), and at one point the lunar module had peaks above them on either side as they came through a wide gap in the Apennines.

The other point of interest, which you can hear in all 3 videos linked below, is Scott saying “Bam!” on touch down. Apparently this was one of the roughest touchdowns ever in the Apollo mission series. In the 15-20 seconds before touchdown lunar dust was kicked up by the landing thrusters, obscuring any view through the side window for last minute manoeuvring, and so they touched down very hard when they cut the thrusters to drop the last 5-10 feet onto the lunar surface, the module coming to rest with a ~6 degree lean. The payload was heavier than usual on this Apollo 15 mission with the rover on board, and the consequent design requirements that gave less clearance under the module. In fact part of the underside of the module was damaged during the heavy landing. They must have been polite back in the day, as Scott’s exclamation on landing was a distinct …. “Bam !!” which you can hear in the videos below.

The first video (last half) is an animation that shows the line of approach beautifully. By comparing Hadley Rille and some low hillocks on Paulus Putredinis near the end of this video and on my image, I have been able to roughly estimate the approach trajectory of the landing module as it came in over the Apennines (white arrow).

The second video shows the final stages of decent of the Falcon lander that carried Scott and Irwin down to the lunar surface, showing both original footage and a paired reconstruction using LROC (Lunar Reconnaissance Orbiter Camera) imagery (for the unbelievers).

The third video is the longest and explains many aspects of the mechanics of the landing.
-https://www.youtube.com/watch?v=cOjZLUO_Bjc
-https://www.youtube.com/watch?v=JYZ3nvLt0N4
-https://www.youtube.com/watch?v=AxqKlDsgMzc

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BruceRohrlach
Bruce Rohrlach
License: None (All rights reserved)
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Apollo 15 Approach Trajectory, 





    
        

            Bruce Rohrlach