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  Why did Apollo 17 have to launch at night?

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Author Topic:   Why did Apollo 17 have to launch at night?
KenDavis
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Posts: 216
From: W.Sussex United Kingdom
Registered: May 2003

posted 12-28-2023 10:50 AM     Click Here to See the Profile for KenDavis   Click Here to Email KenDavis     Edit/Delete Message   Reply w/Quote
Why did Apollo 17 need to launch at night?

I get a launch in early December so that the sun angle at Taurus Littrow was right, but once you are in Earth orbit, and orbiting every 90 minutes, surely you have an opportunity for the Trans Lunar Injection burn ever 90 minutes?

Axman
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From: Derbyshire UK
Registered: Mar 2023

posted 12-28-2023 11:52 AM     Click Here to See the Profile for Axman   Click Here to Email Axman     Edit/Delete Message   Reply w/Quote
You are correct that an Earth orbit repeats every 90 minutes, but the Apollo mission was to the moon. The moon moves about the Earth every 28 days, and the Earth meanwhile moves about the sun, such that there is a window of opportunity that thus launched from Florida a mooncraft can reach the appropriate landing spot with suitable lighting conditions. That window is of the order of four and and a half hours. Fail to meet it and the next window occurs approximately a month later... Which in Apollo 17's case would have been in the very very early hours pre-dawn in January of the following year...

(Arriving at the moon anytime after the four and a half hour window, and before the next monthly slot, would have resulted in the lighting conditions for landing being sub-optimal to the point of impossible.)

Headshot
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From: Vancouver, WA, USA
Registered: Feb 2012

posted 12-28-2023 12:23 PM     Click Here to See the Profile for Headshot   Click Here to Email Headshot     Edit/Delete Message   Reply w/Quote
It was a measure of operational maturity that let Apollo Management feel "comfortable" with the night launch of Apollo 17.

Apollo 13's first launch opportunity to Fra Mauro, on 12 March 1970, would have required a night launch. In mid-December 1969 NASA Management announced a one month delay. The new, 11 April 1970, launch window would occur during daylight hours.

Henry Heatherbank
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Posts: 319
From: Adelaide, South Australia
Registered: Apr 2005

posted 12-28-2023 03:00 PM     Click Here to See the Profile for Henry Heatherbank     Edit/Delete Message   Reply w/Quote
So let’s throw another factor into the mix. If there is any truth to the rumour the White House did not want the mission to occur until after the 1972 Presidential election (to avoid any political damage to Nixon in the event of a mission disaster/loss of crew), would the originally-planned November launch slot have been in daylight or darkness?

Headshot
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From: Vancouver, WA, USA
Registered: Feb 2012

posted 12-28-2023 04:14 PM     Click Here to See the Profile for Headshot   Click Here to Email Headshot     Edit/Delete Message   Reply w/Quote
I have never seen or heard of that rumor.

After the Apollo flight schedule shakeup of 24 Sept 1970, Apollo 17 was penciled in for a June 1972 flight, but that was dependent on the landing target. Thanks to observations and photography from the Apollo 15 mission, Taurus-Littrow was formally designated on 11 February 1972 as Apollo 17's landing target, but it could only be reached late in the year. The only Apollo 17 launch date that I have ever seen was 6 Dec 1972. As I recall, NASA was anxious to fly 17, get the lunar landings over, and move on to Skylab.

Please let us know if you have any specific references to a November 1972 launch date for 17.

Henry Heatherbank
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Posts: 319
From: Adelaide, South Australia
Registered: Apr 2005

posted 12-28-2023 05:29 PM     Click Here to See the Profile for Henry Heatherbank     Edit/Delete Message   Reply w/Quote
See the post on this forum Apollo, Politics, Ed David and Richard Nixon, which discusses the topic. Like I said, just a rumour.

But back to the question: if 17 had gone off in a November launch window, would it have also been a night launch?

Andy Anderson
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Posts: 122
From: Perth, Australia
Registered: Dec 2009

posted 12-29-2023 12:52 AM     Click Here to See the Profile for Andy Anderson   Click Here to Email Andy Anderson     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by Headshot:
Apollo 13's first launch opportunity to Fra Mauro, on 12 March 1970, would have required a night launch.
I guess that was a Flight Plan change, as I have an initial Flight Plan dated December 1, 1969, that lists the Lift Off Time as 1529 CST which I think would have still been in daylight at the Cape?

Blackarrow
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Posts: 3654
From: Belfast, United Kingdom
Registered: Feb 2002

posted 12-29-2023 01:29 PM     Click Here to See the Profile for Blackarrow     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by Henry Heatherbank:
If there is any truth to the rumour the White House did not want the mission to occur until after the 1972 Presidential election?
Not rumour, historical fact. I refer you to John Logsdon's book, "After Apollo? Richard Nixon and the American Space Program", for instance at pp 157-158. In December, 1970, President Nixon made a number of decisions about NASA projects, including delaying Skylab and the shuttle and cancelling Apollo 17. Meeting with key advisers John Ehrlichman and George Shultz, Nixon initially wanted to shift funds intended for Apollo 17 to Skylab and the shuttle, but '...As he discussed his options, he suggested that "politically" it was better not to launch the mission, or at least slip it, "at whatever cost" until after the November 1972 election. His final decision was to cancel the mission.'

This decision took NASA completely by surprise. In early 1971 George Low raised the issue with the White House and George Shultz made it clear to him that the decision was not about saving money, but was based on Nixon's understanding that Apollo 17 would be considerably riskier than the preceding missions. Nixon did not want a possible space tragedy just before the presidential election. Low told Shultz that Apollo 17 could be delayed until December, 1972 [after the election] and when this was later put to Nixon he (initially) agreed to reverse his earlier decision and allow Apollo 17 to proceed AFTER the election.

Nixon's change of mind was certainly, at least in part, due to strong representations made to him by his science adviser, Edward David. David wrote that '...to counter many of the concerns that have been raised about...the last Apollo mission in the few months before November 1972, the Apollo 16 mission could be launched in February, 1972, and the Apollo 17 launch could be scheduled "in mid-November or December..." '

This was not an end to the matter. On 13th May, 1971, shortly before Apollo 15, Nixon suggested the cancellations of Apollo 16 and Apollo 17 to John Ehrlichman, asking him: "Why in the hell would they have to go up there and take a look around the damned thing again?" [We can thank the infamous White House tape-recordings for capturing Nixon's actual words.]

On 19th October, 1971, presidential aide Bob Haldeman asked Nixon to clarify his position on the cancellation of Apollos 16 and 17. Nixon said: "Yes, I do want to cancel them...I just don't think we should take the risk of a possible goof-off in the damn thing."

Again on 24th November, 1971, Nixon emphatically stated that Apollos 16 and 17 would not go ahead, but he eventually conceded: "If we go, no shots before the election." He was finally persuaded that there was a "politically safe" gap between Apollo 16 and the election; and provided Apollo 17 did not fly until AFTER the election, he agreed that both missions could proceed.

I first heard about the near-cancellation of Apollo 17 while carrying out research for my Ron Evans biography, "A Long Voyage to the Moon" and I was frankly shocked to learn how close the mission had been to cancellation. (Neither Barbara Cernan nor Jan Evans had heard anything about this until I interviewed them for my book). I contacted Professor Logsdon, who was kind enough to review and approve the summarized version of the events which I included in my book.

All times are CT (US)

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