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hpr1597 :: Extravehicular Activity

NASA guidelines for EVA from spacecraft are detailed and painstaking, not so films.

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Hosted by Steve Smethurst on 2014-09-16 is flagged as Clean and is released under a CC-BY-SA license.
Listen in ogg, spx, or mp3 format. | Comments (1)

EVA - The Rules for Extravehicular Activity

Here I dip into the NASA experience of and rules for Extravehicular Activity, prompted at first by watching a film called The Europa Report, directed by Sebastian Cordero (2013).

WARNING - THIS PODCAST CONTAINS SPOILERS

While I have some gripes about the film, I was impressed by its general failfulness to the science

  • It thought to find life on Europa, a moon of Jupiter considered by real exobiologists and planetary scientists to be a good candidate
  • Neil deGrasse Tyson made a cameo appearance
  • The portrayal of Europa's geography and character
  • Having to drill through the ice to get at the sea below
  • The behaviour of the crew as scientists and engineers

Science consultant on the film was Kevin Hand, an astrobiologist and expert on Europa at NASA's Jet Propulsion Laboratory

To my mind, the scientists were behaving like scientists and the engineers behaved like engineers. To follow along it might help to recall their names

  • Captain - Willam Xu
  • Pilot - Rosa Dasque
  • Chief scientist - Daniel Luxembourg
  • Marine biologist - Katya Petrovna
  • Junior engineer - James Corrigan
  • Chief engineer - Andrei Blok

All was going scientifically until the director drove the plot forward with two EVA incidents

EVA-1 : Flash back episode, engineers James and Andre go out to fix a failed communications circuit

  • Andre rips his suit
  • James gets squirted with rocket fuel
  • Only one astronaut survives

I have problems with this because it's just too clumsy for trained professional astronauts. Where are the decontamination procedures, the tethers, the special tools?

EVA-2 : Down on the surface, Marine biologist Katya decides to walk out alone

  • Tourtured debate in the ship
  • Of four able and expendable crew members, none go with her
  • Katya does not come back alive

With this I am shouting at the screen "No Way! Where's the fracking operating manual? No one goes EVA on their own"

So, that is why I researched the NASA rules for Extravehicular Activity. And I found that none of these events would have happened the way they were shown, had the crew, who were so professional in every other way, followed the NASA procedures.

The two astronauts issue

  • The most recent occasion where an astronaut went solo EVA was in 1971, when David Scott stuck his head out of the airlock of Apollo 15.
  • Most recent before that was in 1966, when Buzz Aldrin went EVA from Gemini 12 (Gemini craft only had two crew).
  • Since 1971, there have been 358 space walks and every single one has had two crew.
  • I found no written regulation, but de-facto, nobody leaves the spacecraft alone.

NASA procedures

NASA documents on the internet discuss in exhaustive detail all considerations for EVA. What I present is a cherry-picked handful. I could not cover all of it

  • reasons for EVA
  • alternatives
  • planning
  • hazard mitigation
  • procedures for safe conduct
  • fall-back procedures
  • failure handling
  • accident control

International Space Station (ISS) EVA Procedures Checklists

  • Presuming that all the equipment maintenance checks, and readiness checks have alread been done
    • 30 minutes of Airlock preparation and testing
    • 30 minutes of changing components for the suit to fit the astronaut
    • 170 minutes of EVA-Prep
  • Then you are ready to depressurise and leave the airlock
  • EVA might last 2 - 8 hours
  • Post EVA
    • 30 minute procedure to take the suit off
    • 10 minute procedure to disconnect internal equipment
    • Recharge & maintain the Extravehicular Mobility Unit (EMU)
    • Clean & maintain the Suit

Although this podcast is about EVA, it does reference the science in a film that I enjoyed and respect very much, so here is a gem that I only came across while researching the landing site. In the scientific journal Nature, Volume 479, 16 November 2011, Britney Schmidt et al, of University of Texas, Austin, published a paper titled "Active formation of 'chaos terrain' over shallow subsurface water on Europa." In the paper these authors suggest that in the Conemara zone of the Chaos Terrain, an area on the surface of Europa, the ice may be as little as 3 km thick. Then in the film the Conemara Chaos was the targetted landing zone and the drill broke through the ice at a depth of 2800m.

Well there is one more thing that the podcast says, but it is the ultimate spoiler. So if you have not already listened to the podcast, I highly recommend that you watch the film first.


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Comment #1 posted on 2014-10-12T00:25:01Z by noName

Thanks Steve. Enjoyable and informative listening.

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