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Author
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Topic: Apollo EVA count (with equipment jettison)
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LM-12
Member Posts: 3444
From: Ontario, Canada
Registered: Oct 2010
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posted 01-14-2015 09:43 PM
  
On Apollo 17, Jack Schmitt referred to the last post-EVA LM equipment jettison as EVA-4. Gene Cernan called it EVA-5. The LM, of course, had to be depressurized to jettison the unwanted equipment and then repressurized. LMP-LM: Okay, I guess we're GO for EVA-4.
CDR-LM: Five, isn't it? Five this time... If you include all the LM equipment jettisons, how many total EVAs were there on the Apollo flights? I count 26. |
Rick Mulheirn
Member Posts: 4247
From: England
Registered: Feb 2001
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posted 01-15-2015 07:41 AM
Dave Scott's soujourn through the top of the LM docking tunnel on Apollo 15 has been referred to as a "stand up EVA."Throwing the PLSS out the hatch might be considered something similar; "a kneeling down EVA" or perhaps "a stand up and kick it out the door EVA." |
Delta7
Member Posts: 1561
From: Bluffton IN USA
Registered: Oct 2007
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posted 01-15-2015 09:05 AM
The "E" in EVA stands for Extra, meaning "out of" the vehicle (not "Exposure"). So I think one could claim EVA requires at least a partial exit, by definition. |
Robert Pearlman
Editor Posts: 44305
From: Houston, TX
Registered: Nov 1999
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posted 01-15-2015 09:17 AM
The NASA monograph "Walking to Olympus: An EVA Chronology" explains: Russia and the U.S. define EVA differently. Russian cosmonauts are said to perform EVA any time they are in vacuum in a space suit. A U.S. astronaut must have at least his head outside his spacecraft before he is said to perform an EVA. The difference is based in differing spacecraft design philosophies. Russian and Soviet spacecraft have always had a specialized airlock through which the EVA cosmonaut egressed, leaving the main habitable volume of the spacecraft pressurized. The U.S. Gemini and Apollo vehicles, on the other hand, depressurized their entire habitable volume for egress. The U.S. definition of when a spacewalk starts changed with the introduction of the extravehicular mobility unit (EMU) spacesuit used during the space shuttle program (and still in use aboard the space station). Officially, U.S. EVAs using the EMU begin when the astronaut switches the suit to battery power. (Russia still marks the start of an EVA by hatch opening.) |
LM-12
Member Posts: 3444
From: Ontario, Canada
Registered: Oct 2010
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posted 01-15-2015 09:18 AM
The Gemini 10 and Gemini 11 equipment jettisons are included in the Gemini EVA table in NASA SP-4002 Project Gemini - A Chronology. |
LM-12
Member Posts: 3444
From: Ontario, Canada
Registered: Oct 2010
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posted 01-15-2015 04:02 PM
I like the Russian EVA definition: suited up in a vacuum. |
moorouge
Member Posts: 2478
From: U.K.
Registered: Jul 2009
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posted 01-17-2015 01:25 AM
Just to confuse matters further, during the Apollo days EVA times were sometimes recorded as hatch opening to hatch closing and sometimes were recorded as time on the PLSS. |
LM-12
Member Posts: 3444
From: Ontario, Canada
Registered: Oct 2010
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posted 01-17-2015 05:40 AM
Confusing for sure. The Gemini and Apollo-era EVA definition does not seem to include these crew members who stayed inside the spacecraft, even though they were also suited up in a vacuum: - the command pilot during the Gemini EVAs
- McDivitt during the Apollo 9 EVA
- Irwin during the Apollo 15 SEVA
- Scott, Young and Cernan during the transearth EVAs
- the commander and lunar module pilot during LM equipment jettisons
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Robert Pearlman
Editor Posts: 44305
From: Houston, TX
Registered: Nov 1999
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posted 01-17-2015 08:35 AM
quote:
Originally posted by moorouge:
...during the Apollo days EVA times were sometimes recorded
Recorded by who? |
moorouge
Member Posts: 2478
From: U.K.
Registered: Jul 2009
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posted 01-17-2015 03:43 PM
Contemporary press and in letters to me from PAO at Houston. |
Robert Pearlman
Editor Posts: 44305
From: Houston, TX
Registered: Nov 1999
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posted 01-17-2015 03:51 PM
Okay, so unofficial sources. The press can report however they desire and PAO doesn't maintain the official records (the program does). Still, I can see how that can be a point of confusion. |
moorouge
Member Posts: 2478
From: U.K.
Registered: Jul 2009
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posted 01-17-2015 04:11 PM
This is not a new problem as I recorded in the 1975 edition of my booklet "Manned Spaceflight." To quote: In the above table some times are given in reports as PLSS timings, some as hatch to hatch and some as the time actually spent outside the spacecraft. I have every confidence that John McLeaish, the then head of the public affairs office at Houston would have provided information to me that was the best available at the time and that this information would have come from the "program" records. |
Robert Pearlman
Editor Posts: 44305
From: Houston, TX
Registered: Nov 1999
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posted 01-17-2015 04:37 PM
If PAO operated back then as it does today, then McLeaish was providing you with the best information he had at the time, but not necessarily the same as was later considered the official program record.Regardless, NASA has since standardized its EVA record-keeping (as explained above), so that the count remains consistent. |
LM-12
Member Posts: 3444
From: Ontario, Canada
Registered: Oct 2010
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posted 01-19-2015 10:12 AM
The Apollo Program Summary Report has varying definitions for the moonwalk durations shown in Table A-V. - The Apollo 11 EVA duration is based on hatch opening and closing times.
- The Apollo 12 EVA durations are based on egress and ingress times.
- The Apollo 14, 15, 16 and 17 EVA durations are based on when the LM cabin pressure reached 3.0 psi during depressuriztion and repressurization.
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moorouge
Member Posts: 2478
From: U.K.
Registered: Jul 2009
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posted 01-19-2015 10:34 AM
Mmmmm! So much for standardisation then. |
LM-12
Member Posts: 3444
From: Ontario, Canada
Registered: Oct 2010
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posted 01-19-2015 10:45 AM
The transearth EVA durations and the Apollo 9 EVA duration are also based on the 3.0 psi level. Additional Apollo 9 EVA durations are also shown: - hatch open to hatch closed (CMP)
- egress to ingress (LMP)
- arrive at and leave EVA station (LMP)
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LM-12
Member Posts: 3444
From: Ontario, Canada
Registered: Oct 2010
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posted 01-20-2015 07:52 PM
On Apollo 15, the CDR and LMP were "hard-suited" (suits pressurized) for the LM SEVA, the three lunar surface EVAs and the post-EVA equipment jettison. Later, all three crewmembers were hard-suited for the transearth coast EVA.Apparently, all three crewmembers were also hard-suited for the SIM door jettison shortly before entering lunar orbit. From the Mission Report: The scientific instrument module door was jettisoned after the second midcourse correction and prior to lunar orbit insertion. To prepare for this, the crew donned their pressure garments, performed a pressure integrity check, and maneuvered the spacecraft to the proper attitude. Jettisoning of the door was felt as a very light "thud" in the command module. |
LM-12
Member Posts: 3444
From: Ontario, Canada
Registered: Oct 2010
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posted 01-22-2015 02:50 AM
The two standup EVAs by Dave Scott are included in the EVA tables.But the standup EVAs by LMPs Irwin, Duke and Schmitt during the transearth coasts are not included. They are not mentioned in the EVA tables, even though the LMPs stood up in the CM hatch just as Scott did on Apollo 9. A list of when the astronauts were "hard-suited" on Apollo missions would include all the extravehicular activity mentioned in the APSR tables, PLUS: - McDivitt - in LM during Apollo 9 EVA
- Armstrong and Aldrin - LM equipment jettison on Apollo 11
- Conrad and Bean - LM equipment jettison on Apollo 12
- Shepard and Mitchell - LM equipment jettison on Apollo 14
- Scott, Worden and Irwin - SIM door jettison on Apollo 15
- Irwin - in LM during SEVA by Scott
- Scott and Irwin - LM equipment jettison
- Irwin - SEVA during transearth EVA
- Scott - in CM during transearth EVA
- Young and Duke - LM equipment jettison on Apollo 16
- Duke - SEVA during transearth EVA
- Young - in CM during transearth EVA
- Cernan and Schmitt - LM equipment jettison (2) on Apollo 17
- Schmitt - SEVA during the transearth EVA
- Cernan - in CM during transearth EVA
Also, in lunar orbit, the CDR and LMP performed pressure suit integrity checks in the LM prior to CSM/LM undocking. |
LM-12
Member Posts: 3444
From: Ontario, Canada
Registered: Oct 2010
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posted 01-24-2015 05:12 AM
The Apollo 16 and Apollo 17 crews were not hard-suited for the SIM door jettison. YOUNG: Okay, Houston, that was a pretty good bang.CC: Roger. YOUNG: The reason it was is on account of we're standing around here in our underwear, you know. That is, helmets and gloves off. |
LM-12
Member Posts: 3444
From: Ontario, Canada
Registered: Oct 2010
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posted 01-28-2015 08:37 AM
Buzz Aldrin mentioned the post-EVA equipment jettison in the crew debrief:Well, there's no getting around it, it's another EVA PREP exercise. It's easier, but you still have to go through the same exercises such as pressure-integrity check, reading the cabin down, and configuring the ECS. I guess if you have two EVAs, it probably would be nicer to jettison your equipment at the beginning of the second one, rather than having to add another DEPRESS. I'm not sure how they're planning to do this. |
LM-12
Member Posts: 3444
From: Ontario, Canada
Registered: Oct 2010
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posted 06-30-2015 08:07 AM
In the Apollo 16 post-flight debrief, John Young mentions that "we set a new world record for suit donning and doffing in zero gravity and 1/6-gravity seven times... "How does that compare with Apollo 15 and Apollo 17? |
LM-12
Member Posts: 3444
From: Ontario, Canada
Registered: Oct 2010
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posted 01-29-2016 07:25 PM
Here is an Apollo EVA table that does include the transearth LMP standup EVAs by Irwin, Duke and Schmitt. |
Lou Chinal
Member Posts: 1343
From: Staten Island, NY
Registered: Jun 2007
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posted 01-31-2016 05:02 PM
Sort of on the topic, was the docking tunnel hatch open or closed on Apollo 9? |
LM-12
Member Posts: 3444
From: Ontario, Canada
Registered: Oct 2010
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posted 01-31-2016 06:05 PM
The flight plan activity timeline seems to indicate that the tunnel hatch was closed during the EVA. It shows "install tunnel hardware" before depressurization, and "clear and stow tunnel hardware" after repressurization. |
LM-12
Member Posts: 3444
From: Ontario, Canada
Registered: Oct 2010
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posted 02-09-2016 03:29 AM
On Apollo 14, the crew had briefly considered suiting up to inspect the probe after the 5th failed CSM/LM docking attempt following transposition: LMP: Here it comes.LMP: No latch. CMP: No latch, Houston. CC: Roger. CDR: Houston, 14. I'm sure you're thinking about the possibility of going hard suit and bringing the probe inside to look at, as we are. CC: That's affirmative. We may have one more procedure to try prior to going to that. Stand by 1 now. CDR: Okay. The next docking attempt about 25 minutes later was successful. |
LM-12
Member Posts: 3444
From: Ontario, Canada
Registered: Oct 2010
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posted 03-15-2016 09:31 PM
There was a similar docking problem on the Skylab 2 flight. From the mission report: Eight docking attempts were required to successfully achieve a hard docking following the standup extravehicular activity. Although capture latch engagement (soft dock) and undocking were successfully achieved prior to the standup extravehicular activity, the subsequent eight attempts never resulted in capture latch engagement and hard docking was performed using the emergency docking procedure ... the docking problem was similar to an anomaly that occurred on the Apollo 14 mission. The Apollo 14 crew considered suiting-up and depressurizing the CM to inspect their docking probe. The Skylab 2 crew actually did suit-up, depressurize the cabin and remove the hatch to inspect the docking probe after their docking problems. From the transcripts: CC: Skylab, Houston we're AOS at Hawaii.CONRAD: Roger, Houston. You - we've done our second EVA and we have gotten probe ... the docking mechanism - we have removed the screw which unfortunately is now in orbit. But we have the probe cover off and the Apollo cover, and we are just reviewing the procedures ... |
schnappsicle
Member Posts: 397
From: Houston, TX, USA
Registered: Jan 2012
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posted 03-16-2016 07:48 AM
quote:
Originally posted by LM-12:
If you include all the LM equipment jettisons, how many total EVAs were there on the Apollo flights? I count 26.
Everything I count says there were 25 Apollo EVAs (19 times when the astronauts left their spacecraft and six for equipment jettison on the lunar surface.I wonder how LM-12 came up with 26 EVAs. Did I forget one somewhere? Something else worth noting (to me anyway), Apollo 15 was the first mission where the entire crew performed EVA. Apollo 17 was the last time it happened. |
LM-12
Member Posts: 3444
From: Ontario, Canada
Registered: Oct 2010
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posted 03-16-2016 08:14 AM
There were two LM equipment jettisons on Apollo 17.There was a sleep period between the end of EVA-3 and LM liftoff. The PLSS backpacks were jettisoned before the sleep period. After the sleep period, the jettison bag was jettisoned. Schmitt called it a "Short EVA-5" before closing the hatch. |
schnappsicle
Member Posts: 397
From: Houston, TX, USA
Registered: Jan 2012
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posted 03-16-2016 12:31 PM
Thanks for the clarification. For some reason, I didn't know about the second jettison on Apollo 17. |
LM-12
Member Posts: 3444
From: Ontario, Canada
Registered: Oct 2010
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posted 03-20-2016 06:04 AM
From the Skylab 2 post-docking press conference on May 25, 1973: SPEAKER: ...we had to go EVA to remove a cover off the back of the probe, because a shaft had moved. It quite likely was not aligned to come back and if we had retracted in that position then we could have damaged the probe so it could not be used again. The speaker is not identified in the text, but the press conference participants were Bill Schneider, Skylab Program Director; Leland Belew, Marshall Space Flight Center Skylab Program Director; and Kenneth S. Kleinknecht, JSC Skylab Manager. |
LM-12
Member Posts: 3444
From: Ontario, Canada
Registered: Oct 2010
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posted 04-13-2016 09:25 AM
On a Skylab Rescue mission, the stranded crew on the space station would have been hard-suited to jettison their disabled CSM. This is from the "Skylab Spacecraft News Reference" on page 3: There are two emergencies that would necessitate orbital rescue: loss of the CSM's earth-return capability or the medical condition of the crew warrants it. Should either condition occur before the launch of Skylab 4 (last of the primary CSM's), the next CSM on the launch line would be converted into a rescue vehicle. If the emergency occurs after the last CSM is launched, the Skylab backup CSM would be readied for rescue ...Shortly before the rescue CSM arrives at the workshop, the stranded astronauts would don pressure suits, enter the MDA, seal it off, and depressurize it. They would then install the spring-loaded docking probe to separate the disabled craft and move it out of the way of the rescue CSM. If that separation cannot be completed, the rescue vehicle can dock at the side port, which would provide limited but adequate stay time for rescue. However, Flight Director Chuck Lewis indicated that the rescue CSM vehicle would dock first, before the disabled CSM was jettisoned. He discussed a possible Skylab 3 rescue mission at the August 4, 1973 press conference: LEWIS: Okay, they - the rescue vehicle docks in the side port. The present CSM is in the - the end port and well, I don't think I'd want to jettison the command service module I had there if I had any capability at all. And it may be a questionably capability but I wouldn't want to jettison before I dock the other vehicle, then find out I couldn't dock the other vehicle ... when we had the rescue vehicle docked we'd jettison the CSM.The reason for ejection is to provide a capability to return on a subsequent flight to that - that end docking port. Other words, your umbilical - your power umbilical system only works through - and communications only works through that one port. It does not work through the side port. You don't have the capability in the side port you've got on the end port. |
LM-12
Member Posts: 3444
From: Ontario, Canada
Registered: Oct 2010
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posted 06-10-2018 08:55 PM
On Apollo 9, the tunnel hardware (drogue, probe, hatch) was installed during the EVA preparations. The LM overhead hatch was closed.The CM was depressurized about 15 minutes after the LM. After the spacewalk activities, the CM was repressurized about 10 minutes after the LM. So, with the tunnel hatches closed and with different CM/LM depressurization and repressurization times, was there one EVA on Apollo 9, or two?
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Jim Behling
Member Posts: 1530
From: Cape Canaveral, FL
Registered: Mar 2010
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posted 06-11-2018 07:58 AM
quote:
Originally posted by LM-12:
Scott, Worden and Irwin - SIM door jettison on Apollo 15
Putting on a suit and then doing a pressure check does not count. - There is no exposure to a vacuum.
- The pressure check is not the same as the pressure differential in a vacuum.
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LM-12
Member Posts: 3444
From: Ontario, Canada
Registered: Oct 2010
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posted 06-11-2018 08:49 AM
The suit wearing schedule in the Apollo 15 Flight Plan has the crew "hard-suited" for the SIM door jettison. |
Jim Behling
Member Posts: 1530
From: Cape Canaveral, FL
Registered: Mar 2010
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posted 06-11-2018 06:53 PM
Doesn't mean it is an EVA. |
oly
Member Posts: 1076
From: Perth, Western Australia
Registered: Apr 2015
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posted 09-03-2018 02:50 PM
quote:
Originally posted by schnappsicle:
Something else worth noting (to me anyway), Apollo 15 was the first mission where the entire crew performed EVA. Apollo 17 was the last time it happened.
What about the Gemini EVA flights when both crew were suited and exposed to space, or Apollo 9 when all crew were suited and both the LM and CSM hatches were open? |
oly
Member Posts: 1076
From: Perth, Western Australia
Registered: Apr 2015
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posted 09-03-2018 02:53 PM
quote:
Originally posted by LM-12:
The suit wearing schedule in the Apollo 15 Flight Plan has the crew "hard-suited" for the SIM door jettison.
All flights also had the crews "hard-suited" for launch, it's a precautionary measure. Crews were meant to be "hard-suited" during reentry but Apollo 7 crew changed that. |
LM-12
Member Posts: 3444
From: Ontario, Canada
Registered: Oct 2010
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posted 09-03-2018 04:56 PM
The tables seen in the flight plans have the crews "soft-suited" for launch. The tables show four types of suit wearing activity:
- pressurized (hard suit)
- suited (soft suit)
- partial suit without helmet and gloves
- shirtsleeves (ICG)
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oly
Member Posts: 1076
From: Perth, Western Australia
Registered: Apr 2015
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posted 09-03-2018 09:12 PM
Any time the suit is sealed, it has some positive pressure inside, otherwise the pressure outside is greater and results in a squeezing of the astronaut and makes all the seals of the suit work backwards. You cant pump breathing air into the suit and not have some kind of pressurization. To ensure suit seal integrity remains secure, a positive pressure is required. |
David C
Member Posts: 1121
From: Lausanne
Registered: Apr 2012
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posted 09-04-2018 07:33 AM
Yes and no. The suit's really just a rubber bag with hoses and seals. If it's soft, the pressure inside and out is basically the same and air can flow through it — provided of course that flow in and/or out aren't restricted by the suit loop. The suit itself is not completely sealed, just sealed off from the cabin. The suit loop is a different matter. There's no squeezing of the suit occupant if soft suited. A soft suit doesn't support significant "under pressure" so no seals are working backwards. Yes, there's a tiny positive pressure, but it's trivial and nothing like being hard suited. |
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