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Author
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Topic: Gemini 8: David Scott's planned spacewalk
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LM-12
Member Posts: 3428
From: Ontario, Canada
Registered: Oct 2010
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posted 07-20-2013 01:12 AM
  
Here is a description from the press kit of how the Gemini 8 EVA by David Scott would have unfolded had the in-flight emergency not occurred.The Gemini spacecraft and the Agena Target Vehicle would have been docked when the EVA began. It is interesting that Scott would have been in the rear of the adapter section wearing the ESP (Extravehicular Support Package) when Gemini and Agena undocked. At the 18th hour after liftoff, the crew will prepare for the pilot's extravehicular activity. The ELSS chest pack (see Crew Provisions Section for details of EVA equipment) will be unstowed, along with the 25-foot umbilical tether and "Y" connectors. The command pilot will lower cabin pressure to 3.5 psi for systems check and then completely depressurize the cabin. The pilot is scheduled to open the hatch at 20:30 GET, and at sunrise at the end of the 13th revolution, the pilot will emerge from the spacecraft at 20:41 GET.On the first daylight pass over the United States, the pilot will perform the following tasks. While standing on the seat, he will mount the extravehicular camera facing forward, then retrieve the S-9 experiment on the retro adapter directly behind his seat. Then he will move to the target docking adapter and open the S-10 micrometeroid experiment mounted there. He will return to the spacecraft, change film in the camera and face it aft, then clean and sample the spacecraft windows. The pilot then moves to the rear of the adapter section to check the ESP equipment. He returns to the retro adapter and performs the D-16 power tool experiment. Prior to sunset, he moves to the rear of the adapter section to don the ESP. During the night pass (45 minutes) the pilot will stay in the adapter section, donning the extravehicular equipment. At second sunrise, the command pilot will undock the Gemini from the Agena and translate 60 feet out-of-plane to fly formation with the Agena. He will then separate the back pack from the adapter section and the pilot will move to the nose of the Gemini. The EVA pilot will then evaluate the 75-foot tether and the HHMU. He will move out from the spacecraft to the 15-foot point on the tether. The pilot will then translate below the Agena by ten feet, and the command pilot will maneuver the spacecraft to null any angular motion between the spacecraft and the EVA crewman. The EVA pilot will move successively to the 45-foot connect point and the 75-foot connect point on the tether. When he has finished HHMU maneuvers at 75 feet, the command pilot will maneuver the spacecraft to the pilot. The command pilot will follow the pilot as he translates to the Agena. The pilot will then follow the spacecraft at 50 feet as the command pilot translates from the Agena. Ingress will be in the 15th revolution while flying formation with the Agena at 250 feet. Total time of EVA will be two hours, 10 minutes. After EVA is completed, the command pilot will re-dock with the Agena. |
Tom
Member Posts: 1619
From: New York
Registered: Nov 2000
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posted 07-20-2013 08:29 AM
Quite a bit more complicated than previous EVA on Gemini 4! |
garymilgrom
Member Posts: 1966
From: Atlanta, GA
Registered: Feb 2007
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posted 07-20-2013 09:16 AM
Very surprised they would have someone outside during an undocking. That seems overly risky for the second EVA but it also shows NASA's can-do attitude from this time. |
LM-12
Member Posts: 3428
From: Ontario, Canada
Registered: Oct 2010
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posted 07-20-2013 10:04 AM
Dave Scott would have jettisoned the Extravehicular Support Package (ESP) and the 75-foot tether aft of the Gemini spacecraft just before EVA ingress. |
Fra Mauro
Member Posts: 1655
From: Bethpage, N.Y.
Registered: Jul 2002
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posted 07-20-2013 01:04 PM
It also shows to me how unknown the complexities of an EVA were understood back in 1966. Imagine the disaster if the thruster problem had occurred during the EVA. |
LM-12
Member Posts: 3428
From: Ontario, Canada
Registered: Oct 2010
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posted 07-20-2013 01:40 PM
This photo of the EVA equipment for Gemini 8 shows the chest-mounted ELSS and the ESP back pack. He is holding the HHMU in his right hand. The ESP was similar in shape to the AMU on Gemini 9A. quote:
Originally posted by garymilgrom:
Very surprised they would have someone outside during an undocking.
That was the plan for Gemini 9A also. Tom Stafford was to undock the Gemini 9A spacecraft from the ATDA while Gene Cernan was in the adapter section strapped to the AMU. |
mach3valkyrie
Member Posts: 719
From: Albany, Oregon
Registered: Jul 2006
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posted 07-20-2013 10:36 PM
Imagine the photographs of Scott's EVA had the mission proceeded as planned! |
LM-12
Member Posts: 3428
From: Ontario, Canada
Registered: Oct 2010
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posted 07-20-2013 10:56 PM
Gemini 9A had a docking bar mirror. Gemini 8 would have had one also. One of the early EVA tasks for Dave Scott was to "attach mirror to docking bar" shortly after exiting the hatch. The mirror would have been in his suit pocket.Neil Armstrong would have had a great view of the EVA just as Tom Stafford did. |
LM-12
Member Posts: 3428
From: Ontario, Canada
Registered: Oct 2010
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posted 07-23-2013 02:59 PM
... and at sunrise at the end of the 13th revolution, the pilot will emerge from the spacecraft ... Here is how the Gemini press kit explains orbits and revolutions: The spacecraft's course is measured in revolutions around the Earth. A revolution is completed each time the spacecraft passes over 80 degrees west longitude, or at Gemini altitudes about once every 96 minutes.Orbits are space referenced and in Gemini take about 90 minutes. The longer time for revolutions is caused by the Earth's rotation. As the spacecraft circles the Earth, the Earth moves about 22.5 degrees in the same direction. Although the spacecraft completes an orbit in about 90 minutes, it takes another six minutes for the spacecraft to reach 80 degrees west longitude and complete a revolution. Gemini completes 16 orbits per day, but in 24 hours crosses the 80th meridian of longitude 15 times -- hence 15 revolutions per day. |
onesmallstep
Member Posts: 1320
From: Staten Island, New York USA
Registered: Nov 2007
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posted 07-24-2013 10:45 AM
For those that may not have seen it, Space History Photo of the Week 373 (12/24/11) has a photo of Cernan taken by Stafford using the docking bar mirror used on GT-9A. |
LM-12
Member Posts: 3428
From: Ontario, Canada
Registered: Oct 2010
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posted 07-24-2013 12:12 PM
The flight plan indicates that Gemini 8 and Agena would have been docked when the EVA began, with the Agena at 0, 90, 0 degrees and the spacecraft at 0, -90, 0 degrees. I'm guessing that is 90 degree yaw, and perpendicular to the direction of flight. |
LM-12
Member Posts: 3428
From: Ontario, Canada
Registered: Oct 2010
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posted 07-24-2013 04:03 PM
Here are two colour photos of the Gemini 8 EVA equipment: 1 | 2 |
LM-12
Member Posts: 3428
From: Ontario, Canada
Registered: Oct 2010
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posted 07-26-2013 09:32 PM
This paragraph is from the program mission report for Gemini 8:A hatch holding device was added to both hatches. This was a tooth and ratchet system with the tooth mounted on the center torque box of the cabin and the ratchet attached to the hatch. To provide EVA capability through either hatch, a hatch closing device and attaching eyebolts were added to the left hatch and were the same as the existing installation on the right hatch. Hatch rigging procedures were changed to insure compatability with the hatch holding device. |
Delta7
Member Posts: 1553
From: Bluffton IN USA
Registered: Oct 2007
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posted 08-06-2013 10:32 PM
Interesting to remember this EVA was the main reason that Elliot See was bumped from the flight by Deke Slayton and promoted to Command Pilot of Gemini 9. |
LM-12
Member Posts: 3428
From: Ontario, Canada
Registered: Oct 2010
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posted 09-21-2013 01:21 AM
In this clip, you can see the EVA equipment in the Gemini 8 adapter section as the spacecraft is hoisted up to the white room at Pad 19. |
carmelo
Member Posts: 1055
From: Messina, Sicilia, Italia
Registered: Jun 2004
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posted 06-28-2020 08:12 AM
If Gemini 8 mission had no problems, and the Dave Scott's EVA had happened, is plausible said that in any case would have failed?The lack of pool training in those days, the underestimated effort with a very few flexible space suit (when pressurized), the "fog" problem in the helmet and the ambitious goal of the Scott's EVA would have produced a failure. Do you agree? Editor's note: Threads merged. |
David C
Member Posts: 1098
From: Lausanne
Registered: Apr 2012
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posted 06-28-2020 08:44 AM
It's entirely plausible that it would have failed, it's impossible to say. That's probably the most likely outcome.However, Scott was maybe a bit smarter, stronger and better trained. Armstrong was probably a less directive commander than Stafford. Maybe Scott, given the opportunity, would have just been able to get it done. Or maybe he'd have got into a hole he couldn't get out of. We'll never know. |
MCroft04
Member Posts: 1662
From: Smithfield, Me, USA
Registered: Mar 2005
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posted 06-28-2020 10:18 AM
I had a good discussion with Dave about this planned EVA years ago. He was absolutely convinced (no surprise I guess) that he would have been successful — primarily because he had trained a lot longer than Cernan did on Gemini 9A. |
David C
Member Posts: 1098
From: Lausanne
Registered: Apr 2012
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posted 06-28-2020 12:00 PM
Perhaps it's more interesting to ask if it would have been a good thing overall for Scott to have succeeded?What would the plan have been for the Gemini IX EVA if VIII had succeeded? |
Robert Pearlman
Editor Posts: 44147
From: Houston, TX
Registered: Nov 1999
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posted 06-28-2020 01:02 PM
I would think the Gemini 9 EVA plan would have remained mostly unchanged, proceeding with an attempt to fly the Astronaut Maneuvering Unit (AMU). Gene Cernan would have had the advantage of what Dave Scott learned on Gemini 8, so maybe he would have been able to avoid the troubles he had with his suit and helmet. If so, then perhaps it was better for all involved that Scott did not get to spacewalk, as the way I understand it, the AMU presented some real concerns to crew safety (with the benefit of hindsight). |
carmelo
Member Posts: 1055
From: Messina, Sicilia, Italia
Registered: Jun 2004
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posted 06-28-2020 07:20 PM
If the pool training procedure for EVA had been established in 1965, and not in late 66, what would have changed for the EVAs of Gemini 8 (if happened), Gemini 9, Gemini 10 and Gemini 11? |
Skylon
Member Posts: 286
From:
Registered: Sep 2010
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posted 06-28-2020 07:38 PM
It's interesting the comparison between crews is being brought up. I remember in "Carrying the Fire" Michael Collins mentioned talking to Armstrong at one point and saying he considered it maybe lucky Scott never carried out his EVA. Armstrong, retorted that Collins' Gemini 10 EVA with the inert GT-8 Agena was ill-conceived and that Collins was lucky to have pulled it off."The devil you know" seems to be a factor in how astronauts from the era themselves evaluated the Gemini EVAs. |
Robert Pearlman
Editor Posts: 44147
From: Houston, TX
Registered: Nov 1999
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posted 06-28-2020 08:00 PM
quote:
Originally posted by carmelo:
...what would have changed for the EVAs
Neutral buoyancy training primarily prepares astronauts for how to control their bodies and help plan out where handholds may be desired. Gemini 8 and 9's biggest hurdles were equipment related (both planned and unplanned), which could still have been missed in the pool. |
LM-12
Member Posts: 3428
From: Ontario, Canada
Registered: Oct 2010
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posted 06-29-2020 09:49 AM
The Gemini 8 spacecraft is on display in Wapakoneta, Ohio. Here is a view of the
main control panel. I believe that is the "Back-Pack Deploy/Safe" switch seen behind the mirror.
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Headshot
Member Posts: 924
From: Vancouver, WA, USA
Registered: Feb 2012
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posted 06-29-2020 11:03 AM
Does anyone know if Dave Scott would have approached his EVA as a muscle-through-it Cernan type or a slow-steady-careful Aldrin type? |
carmelo
Member Posts: 1055
From: Messina, Sicilia, Italia
Registered: Jun 2004
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posted 06-29-2020 01:24 PM
My wonder is this: why pass from the "easy" EVA of Ed White, that simply floated around, to a difficult, ambitious, hazardous EVA as planned for Scott?Wouldn't have been better for the second American EVA a more long "Ed White type" EVA? |
Robert Pearlman
Editor Posts: 44147
From: Houston, TX
Registered: Nov 1999
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posted 06-29-2020 02:04 PM
Ed White's EVA was a quick answer to Alexei Leonov becoming the first spacewalker. White was originally planned to only stand up in his seat. The eight months between Gemini 4 and Gemini 8 gave NASA the time to develop an EVA plan that would support the skills needed to go to the moon. White's EVA was only about showing that NASA could spacewalk, too. |
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