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Author
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Topic: Night launches: Explorer 1 to Apollo 17
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DFBrunswick
Member Posts: 40
From: California, USA
Registered: May 2015
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posted 05-10-2017 04:51 AM
   
I would think the night launches would be very undesirable from a flight preparation standpoint.So does anyone know why Apollo 17 was launched at night? Obviously it relates to the lunar launch window but why not wait until the month of January 1973 when a daylight launch might have been possible? America's first satellite, Explorer I, was also launched at night. Does anyone know why? |
Mike Dixon
Member Posts: 1428
From: Kew, Victoria, Australia
Registered: May 2003
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posted 05-10-2017 06:15 AM
Faint memories, but I recall comments to the effect they wanted the program to go out on a high with a night launch. Might have been journalistic license. Regardless, I'm happy they did. |
Ronpur
Member Posts: 1220
From: Brandon, Fl
Registered: May 2012
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posted 05-10-2017 07:31 AM
According to Gene Cernan's book, Apollo 17 had to do with the landing location and the need to land there early in the lunar day, so the LM could land with the back to the sun. |
Blackarrow
Member Posts: 3160
From: Belfast, United Kingdom
Registered: Feb 2002
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posted 05-10-2017 09:50 AM
Cernan's account doesn't deal with the issue of delaying the mission until January 1973. Two reasons occur to me: - This would have meant lot of preparation work and a lot of expensive overtime over the Christmas and new year period.
- Second, a launch in January would be getting uncomfortably close to the Skylab launch. A launch delay from January until February 1973 would have caused problems for Skylab.
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Headshot
Member Posts: 891
From: Vancouver, WA, USA
Registered: Feb 2012
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posted 05-10-2017 10:55 AM
By December 1972, NASA had nine consecutive, highly-successful, manned Saturn V launches. So obtaining a waiver for the ban on a night launch was not a significant risk.Also, had NASA waited until January 1973, they would have had just three launch opportunities that month (the 4th, 5th and 6th) and only two in February (the 3rd and 4th). After that, Taurus-Littrow would have been out of reach for a while. Had NASA been unable to launch Apollo 17 by February, they might have just cancelled the mission in order to move on to Skylab. |
DFBrunswick
Member Posts: 40
From: California, USA
Registered: May 2015
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posted 05-13-2017 05:32 PM
Really excellent responses Blackarrow and Headshot. Totally makes sense about Skylab and the landing site being out of reach.So some ancient history here, does anyone know why Explorer 1 was launched at night? |
Headshot
Member Posts: 891
From: Vancouver, WA, USA
Registered: Feb 2012
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posted 05-14-2017 09:19 AM
The Explorer 1 night launch is an interesting issue. My guess is the answer might lie in contemporary accounts (magazines or newspapers) of the launch. There could have been equipment issues and/or weather issues that delayed/extended the launch time from daylight to night. |
Robert Pearlman
Editor Posts: 43576
From: Houston, TX
Registered: Nov 1999
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posted 05-14-2017 09:58 AM
Based on a memo documenting calls between Brig. Gen. Andrew Goodpaster and James Hagerty (White House Press Secretary) on Jan. 31, 1958, it was the weather that pushed the launch of Explorer I into the evening. 2:30 p.m. — On arrival in Augusta, I called General Goodpaster at the White House and he told me that high winds in the stratosphere were still postponing the Jupiter-C shooting. I relayed this information to the President in his cottage at the Augusta National Golf Club.5:55 p.m. — General Goodpaster called me at my room at the Bon Air Hotel to tell me that the weather was improving at Cape Canaveral and that the Army was going to try to shoot the Jupiter-C tonight at 10:30 P.M. plus four minutes... 8:30 p.m. — General Goodpaster called me again at this time and told me that the weather had improved to the point that it was acceptable as of now, that the Army was planning to go ahead and that they were beginning fueling of the rocket as of 8:30... 9:50 p.m. — General Goodpaster called again to say that the launching was definitely on and that he was leaving his home at this time to go to the office. He said that they were still four minutes behind schedule and that the launching was scheduled for 10:34 P.M. The entire memo is reprinted in "Exploring the Unknown: Selected Documents in the History of the U.S. Civil Space Program, Vol. IV: Accessing Space" edited by John Logsdon. |
Headshot
Member Posts: 891
From: Vancouver, WA, USA
Registered: Feb 2012
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posted 05-14-2017 02:11 PM
Very nice find Robert.Most of the contemporary accounts I located dealt with the Jupiter-C rocket, the "thrust" of the various stages, the satellite itself, and its scientific findings. Being a military operation (Army), and maybe because of the Navy's Vanguard fiasco, these accounts had little to nothing about preparation or launch activities. Even the early Feb. 1958 Aviation Week article was so short on details that not even the "blast-off" time was given. |
Robert Pearlman
Editor Posts: 43576
From: Houston, TX
Registered: Nov 1999
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posted 05-14-2017 03:45 PM
Unlike the Vanguard attempts and later flights, the Explorer I launch was not announced in advance. As John Logsdon notes in "Exploring the Unknown," the White House decided to announce the launch only after the satellite was in orbit. |
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