hpr-knowledge-base/hpr_transcripts/hpr1597.txt

Episode: 1597
Title: HPR1597: Extravehicular Activity
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr1597/hpr1597.mp3
Transcribed: 2025-10-18 05:36:51

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It's Tuesday 16th on September 2014.
This is an HBR episode 1597 entitled Extravitical Ractivity.
It is hosted by Steam's Measures and is about 15 minutes long.
Feedback can be sent to Steam's Measures at disco.co.uk or by leaving a comment on this
episode.
The summary is NASA guidelines for either from spacecraft or detailed and painstaking,
not so films.
This episode of HBR is brought to you by Ananasthost.com.
Get 15% discount on all shared hosting with the offer code HBR15.
That's HBR15.
Get your web hosting that's honest and fair at Ananasthost.com.
Hello, my name's Steve Smithers.
This is my first HBR.
Maybe one day I'll do a what's in my bag or how I got into Linux.
This one is about EVA, extra vehicular activity in space.
Why EVA?
Well, I like sci-fi and it all started with seeing a sci-fi movie, The Europa Report, made
in 2013 by Sebastian Cordero.
It's an interplanetary mission in the search of life.
It chose Europa, a moon of Jupiter as its destination, and I liked the way its characters
behave.
The engineers behave like engineers, the scientists behave like scientists and the captain behave
like a captain.
This had to say is in stark contrast to Ridley Scott's 2012 film Prometheus, where nobody
behaved like anything you would let into a scientific mission, let alone on board a spacecraft.
I'd better give you a warning, this podcast does contain spoilers.
OK, so I like sci-fi that takes its science seriously.
I like 2001 a space Odyssey by Arthur C. Clarke and Stan the Cubric.
I like Moon, made by Duncan Jones in 2009.
But I have a gag reflex that prevents me from ever watching science again, that film
by Emnight Shyamalan, but in 2002.
Incidentally, 2001 I'd probably the most famous EVA in movie history, when Dave Bowman,
without a helmet, blew himself into the Discovery airlock.
So there I am one evening, enjoying a sci-fi adventure thinking, wonder what they make
of Europa?
Oh, it's an icy ball with lots of radiation.
Who's that?
Oh, it's Neil deGrasse Tyson.
Wonder what they do to land?
Hmm, that looks rather Apollo-like.
Wonder how they look for life, drilling through the ice, that's the ticket.
Later I find out that they had a consultant on set, guy called Kevin Han, an astrobiologist
and expert on Europa, from NASA's Jet Propulsion Laboratory.
By now I'm expecting good stuff from this movie, maybe more than just a nod to the science.
But then what happens?
To EVAs.
EVA1.
In a flashback during the journey, two engineers James and Andre go EVA to fix a failed
communication system.
Andre vips his suit and James gets squirted by rocket fuel, only one astronaut survives
and thinking, that's pretty damn clumsy, there just has to be procedures to stop that kind
of thing happening.
Where are the tethers, where are the special tools, where are the decontamination procedures?
Then comes EVA2.
Down on the planet now, with no conclusive signs of life, marine biologist Katya is getting
frustrated.
So she decides to walk to a more promising location, alone.
Stop!
No way!
You wouldn't do that!
There's got to be some operating manual somewhere that says, don't leave the spaceship on your
own.
One of the four other crew members could and should go with her.
I exclude Rose of the pilot, who has to fly the survivors back on what may.
Katya goes out alone and you guessed it, does not come back.
Now, with 50 years of space flight to date, not one cosmonaut, or astronaut, or space navigator
as the Chinese called theirs, have ever dined on an EVA.
And that's not because EVA is at a walk in the park, it's because of the phenomenal
design, planning and care that go into making EVA happen.
So we're starting looking at the NASA rules for handling EVAs.
Let's take the two astronaut issue.
There's not been one man EVA since 1971, when David Scott stuck his head out of their
lock of Apollo 15.
Before that, Buzz Aldrin walked alone from Gemini 12 in 1966.
So although I couldn't find written, thou shalt not EVA alone, in the 358 space walks
since 1971, all have had two crew members.
Also categorize EVAs in different times.
There are planned and unplanned, there are mission enhancing, mission success and safety
critical.
There are simple, specialist and complex EVAs.
Reasons for going EVA as NASA recognizes the need for moving a payload, for maintenance,
for experimentation, for personnel transfer, and for satellite deployment or retrieval.
It's recognised that there are advantages of extra vehicular activity.
You can work flexibly in many ways.
You can be more dexterous than can an automated system.
You can see more clearly than through a camera what's needed.
Hazards are listed as things like sharp edges, pinch points in kick loads and touch temperatures.
Now surfaces in space are really cold and the gloves have to be heated.
Whoever has a disequipment failures, you can have venting of equipment, you can have
corrosive leaks, explosions, ruptures, battery leaks, electrical discharge, molten metal
from welding equipment, you can get tethers breaking or being caught.
There are environmental hazards like radiation, fluids have been discharged in space, micrometeous,
debris.
All of these things can be very hazardous to anyone on the outside of a spacecraft.
NASA recognises limitations of extra vehicular activity.
There can be sensory degradation.
There's a limited time you can stay out there, wire out you have limited mobility.
So there's a huge number of design considerations.
Many of these, most of these are designed in advance of the mission and built into the
mission programme.
Design considerations can include things like vision being affected by variation in atmospheric
attenuation, being affected by transmission of light through helmets and visors.
I hand coordination for the suited EVA crew member is modified by the limits of the
space suit.
Sensory perception and reaction time are altered because of space-suiting combrances.
Food and drink must be included for the total EVA duration.
Air passages within the suit must be protected from vomit.
There must be subsystems for the containment of urine, mences and diarrhea.
Of course, EVA radiation doses will depend on radiation exposure limits set for the
entire mission and wire out on EVA, that's just one portion of your whole dose.
There are other detailed considerations like restraint design for tethers, hooks,
footholds, workspaces, designing your field of view, designing the operating controls
that can be worked from inside a space suit, designing the lighting to give you a proper
view of what it is that you're trying to work on.
Airlock design has to provide sufficient passageways for suited crew and there must be mobility
and transport aids to help the crew member navigate around the outside of the vehicle.
Now bear in mind that what I've done here is just cherry pick some of the considerations
that are listed by NASA, but then there's actually the EVA procedures checklist and this
is when you're actually preparing for and executing an EVA.
Now presuming that all the equipment maintenance checks and readiness checks have already
been done, you have about 30 minutes of airlock preparation and testing, you have another
30 minutes of changing components for the suit to fit the astronaut, modern thinking
is for standard components to be assembled to make a suit for any crew member, rather
than have each crew member having their own suit.
It takes 170 minutes to prep for an EVA, the procedure includes things like positioning
heart rate monitors, it says take one aspirin tablet, there's a 50 minute pre-breathe test
for both crew members involving exertion and blood oxygen level tests.
You have to configure the communication system to minimize noise, then you can put on
the communications cap, you check communications, you verify that biomedical data reads through
the COMS channel, you have to stow your IV glasses, gotta have shades to look cool space,
you have to lock the waistring, you have to check the electric harness, you check the
drink valve position, you put on the gloves, you lock the gloves, you check the glove heaters,
you check the wrist mirrors, you put on the helmet, you close the helmet, you find the
EMU TV power cable, you connect the EMU TV count power cable to the TV, you check for cooling,
you check the water, you check the power, you check the fans, you check the communications,
you check for air leaks, you check all your ordinary tools, the specialist tools, the restraints,
the harnesses and the bungees, and when you've done that and more, then and only then
are you ready to depressurise and leave the airlock, and an EVA may last between 4 and 8 hours.
After the EVA, there's a 30 minute procedure to take the suit off, a 10 minute procedure
to disconnect internal equipment, for the EMU you have to recharge the water supply, recharge
the EMU oxygen supply, replace the EMU battery, power down the EMU and stow the EMU correctly.
For the suit, you have to recharge the in-suit battery, you replace the in-suit equipment,
recharge of light bulbs and things, you have to clean the suit and you have to deal with
waste water dumping. Now that is detail. This podcast is not about the scientific accuracy
of the movie, it's about spacewalks. Having said that though, I've just got to throw
in this gem. In nature, volume 479 on 16th November 2011, Brittany Schmidt et al, researchers
at the University of Texas, Austin, published a paper called Active Formation of Chaos
Terrain over shallow subsurface water on Europa. They described how in the Conamara Zone
of the Chaos Terrain, part of Europa's surface, the ice may be as little as 3 kilometres thick.
Then in the film, the Conamara Chaos was the target zone and the drill broke through
the ice at 2,800 metres. Now you've got to be impressed by that. However, here's the
ultimate spoiler. In the end, there is a monster. Protoplasmic slow to just wouldn't
fill the cinemas, it had to be a monster. This is Steve Smithers for Hacker Public Radio,
I'll see you again sometime.
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