Tuesday 30 July 2019

Moon Tuesday 16th July 2019

Here's a photo of the Lunar eclipse 4 days before the Apollo 11 moon landing anniversary.

But a question:
Why are there no photos of the Apollo 11 capsule re-entering Earth to splashdown?

The USA had high-altitude, high-mach number planes, such as the Lockheed SR-71 Blackbird (2,380 mph / Mach 3.32 & 85,000 ft / 16.1 miles) and the North American Aviation X-15 (4,520 mph / Mach 5.89 & 354,330 ft / 67.1 miles). Also the Apollo 11 flight journal says that a Boeing C-135 Stratolifter "will attempt to photograph this re-entry of the Command Module ... on 70mm still film." The C-135 was capable of 580 mph / Mach 0.76 & 50,000 ft / 9.5 miles.

But you have to think about how fast the Apollo 11 capsule was during reentry.

At Earth Entry (400,000 ft / 75 miles) it was travelling at c.81,000 mph / mach 105.5!

Complicated science involving the blunt high-drag design of the capsule and the atmosphere loosing the capsules kinetic energy through gas friction slowed that down to c.300mph / mach 0.4 at 23,300 ft / 4.4 miles when the drogue parachutes could be deployed. It did this in about 9 minutes!

But they did manage to take such a photo, of the Apollo 8 reentry!
https://spaceflight.nasa.gov/gallery/images/apollo/apollo8/html/s69-15592.html

Check out these references:
https://history.nasa.gov/SP-4029/Apollo_18-40_Entry_Splashdown_and_Recovery.htm
https://history.nasa.gov/afj/ap11fj/26day9-reentry.html
https://www.bbc.co.uk/bitesize/clips/zphpg82
https://en.wikipedia.org/wiki/Atmospheric_entry

Time 22:55.
Distance 246,189 miles.
Full moon phase.
150 degrees SE compass point (azimuth).
Altitude 8.8 degrees.


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