Index Home About Blog
From: (Henry Spencer)
Subject: Re: EVA Glove Improvements?
Date: Wed, 17 Feb 1999 23:16:41 GMT

In article <tYFy2.7112$>,
Ken Glover <> wrote:
>...until your fingers become raw from working for a time against the stiff,
>pressurized glove fingers. Ow, it hurts just to think about trying to do
>fine-control stuff with really sore fingers at about 6 hours into the third

As with a lot of things, practice and training helps.  Jack Schmitt made a
real effort to strengthen and toughen his hands before Apollo 17, and it
made a considerable difference.

(In general, physical fitness makes a real difference for spacesuit work.
One reason why NASA was slow to wake up to the difficulty of spacewalks
was that its first and third spacewalkers happened, quite by accident, to
be in superb physical condition.  Ed White was an Olympic-class athlete;
Michael Collins wasn't quite in that league, but he was easily the most
athletic of the rest of the astronauts.  So it wasn't until Gemini 11,
when Gordon had a lot of the same problems Cernan had on Gemini 9, that
JSC realized that there was a real issue there.)
The good old days                   |  Henry Spencer
weren't.                            |      (aka

From: (Henry Spencer)
Subject: Re: Temperature control in spacecraft.....
Date: Sun, 21 Mar 1999 03:40:54 GMT

In article <7ctpgd$18$>,  <> wrote:
>...then why did the
>Apollo 11 astronauts have the liquid cooling system in operation
>in their suits when they were trying to sleep?  Were they unable
>to turn it off?

Remember, they still needed some cooling -- without it, they'd quickly
have been dripping sweat inside the suits.  (This is why the Apollo 13
astronauts did not don their spacesuits when they started having trouble
with the cold.)

>> ...The MLI insulation used was very good. A 100 K difference
>> between the inside and outside of the suit would have resulted
>> in essentially no heat flux through the suit.
>Has any of this MLI (Multilayer Insulation) been commercialized?

There are people who'll sell it to you, although it's of limited use for
normal applications because it only works really well in vacuum, and it is
expensive.  There's no big mystery about it:  it's multiple layers of very
thin metallized plastic, with layers of netting or other low-conductivity
spacer in between.  Details of seams, penetrations, etc. are important,
and it has to be vented to let trapped gas get out.

>...Is there any data on the total mass
>of ice sublimated for cooling for the various Apollo missions?
>Knowing required quantities for cooling water (ice) requirements
>would be important for launch weight considerations.

Remember that the human body is a net exporter of water -- animal
metabolism converts food plus oxygen into carbon dioxide *plus water*.
Some of this comes out as water vapor from the lungs, and water extracted
from the air was used to extend the cooling-water supplies.  So there is
no simple relationship between sublimator requirements and how much water
had to be aboard at launch.
The good old days                   |  Henry Spencer
weren't.                            |      (aka

From: (George Herbert)
Subject: Re: Spacesuits (was Re: Hilton Space Hotel)
Date: 8 Apr 1999 15:24:42 -0700

note added...

<> wrote:
>[re Mars spacesuits]

Frank Crary and Myself participated in Mars EMU / suit design
study work at UC Berkeley under Larry Kuznetz (along with
about 15 others), and have worked with him a bit since
and some independent work.  Papers will be in the Case 5
and 6 proceedings when those ship.

>0)  Very little MLI (multilayer insulation).  MLI is central to the thermal
>design of almost all spacecraft including spacesuits, but it is *useless* on
>Mars unless it is in a hard vacuum shell.

Yeah, but alternate non-MLI insulation technologies are easily
substitutable.  More mass intensive, but they work.  MLI stops
working around 2 millibars, if I remember the chart right.

>1)  A variety of parka/snowsuit combinations for handling different seasons.
>(I think ALL of the current paintings of astronauts walking around on Mars
>are inaccurate for lack of this.)

Not Carter Emmart's, he was with us during much of the Berkeley study.

>2)  Removable mittens.  These would not replace robust, tactile, pressure
>gloves, but they would be very useful in keeping the hands warm.  They would
>probably need to be actively heated (see #3).

Yeah.  That idea goes back some time.

>3)  A liquid HEATING garment.  This might be similar to the active cooling
>garment used with current suits.  It might occationally be used for cooling.

We* found that generally you're generating an excess of metabolic heat
unless you're sitting immobile for a serious length of time during
coldest conditions (unpressurized rover drivers, at night, midwinter).
Several metabolic models combined with workload models from Lunar,
Earth, and simulated Martian G exertion show that you nearly never
need external heat in practice.

[* This particular we being the group's thermal modeling people during
the Berkeley study, and Frank independently afterwards with his own
modeling efforts.  I have not directly done any of the modeling, just
used the results].

>4)  A rear entry hatch like the Russian Orlan suit.  (There are a number of
>other nifty features, but I like this one best.)

I like the Orlan, but I'm not sure if this particular feature
works well for worn-under-gravity-lod suit designs.
In particular, the waist and hips mobility with a rear-hatch
type suit appear problematic, though not insolvable.

>What's missing from this list?  Any suggestions?

Lighter weight (current suits, even Apollo suits,
are way too heavy for reasonable use on Mars).

Possibly cooling by sweat transpiration through
the suit (using dense membrane polymer technology
for the bladder, etc).  That lets you drop the
LCG mass and bulk entirely.

-george william herbert
Retro Aerospace

From: (Henry Spencer)
Subject: Re: Spacesuits (was Re: Hilton Space Hotel)
Date: Sat, 10 Apr 1999 22:18:37 GMT

In article <>,
 <> wrote:
>>0)  Very little MLI (multilayer insulation).  MLI is central to the thermal
>>design of almost all spacecraft including spacesuits, but it is *useless* on
>>Mars unless it is in a hard vacuum shell.
>All insulation is essentially multilayer: that's why I wear a sweater
>under my jacket.

MLI refers to a specific technology, not to the general idea of multiple
layers.  MLI's effectiveness drops dramatically with even slight gas
pressure, because its approach to reducing conduction losses depends on
being in vacuum.  Its effectiveness doesn't decline to zero, but it does
decline far enough that other insulation types are superior.

>>1)  A variety of parka/snowsuit combinations for handling different seasons.
>I can't dissagree, but how much heat loss to we really expect?  200 Km
>winds at -50ยบ C  is pretty cold, but it's so close to a vacuum that it
>may not have that serious a windchill.

To a first approximation, it's a matter of how much mass is swept past.  A
200km/hr wind at 6-7mbar is equivalent to about a 1.5km/hr wind at 1bar...
and even a faint breeze at -50degC quickly becomes very unpleasant, with a
*much* higher heat removal rate than still air.  (I grew up on the
Canadian prairies, where such temperatures are not unheard-of in winter.)
Even at lower wind speeds, the cooling effect of the air is significant.
Mars air is not close enough to vacuum to be negligible.
The good old days                   |  Henry Spencer
weren't.                            |      (aka

From: (Henry Spencer)
Subject: Re: Space "Capsule" Space Suits... a possible alternative?
Date: Wed, 19 Jan 2000 21:49:10 GMT

In article <>,
Robert Lynn  <> wrote:
>I am sure this has been suggested before but why not just integrate
>mechanical actuators to counter this problem and make the joints
>'neutral' in terms of the force required to bend them.  These actuators
>could be simple springs and strings on the outside of the suit...

The existing suits use "springs and strings" quite extensively in an
attempt to balance forces on the joints.  Without that, they'd work even
more poorly than they do.  There's no obvious way to get further large

>...alternatively they could be a more active system where the
>suit has pressure sensors inside it that sense when the body is pressed
>up against it and actuators that move the joints to reduce that
>pressure, sort of a Robert Heinlein "Starship Troopers" power suit.

This is beyond current technology, both in lightweight powerful actuators
and, more important, in sensors and controls for them.  People have been
talking about "man amplifiers" -- powered exoskeletons -- for use on Earth
for decades now, and nobody has managed to build one that works decently.
There is considerable incentive; they would have many uses.

>Another thought; would it be helpful to use an O2-He gas mix in the
>suits to improve heat transfer around the suit.

No.  The current suits do their heat transfer with water cooling, running
cooling water through flexible tubes sewn into an undergarment.  This is
far better than any gas mix.
The space program reminds me        |  Henry Spencer
of a government agency.  -Jim Baen  |      (aka

From: (Henry Spencer)
Subject: Re: Mars (probably off Topic!)
Date: Mon, 23 Oct 2000 17:35:13 GMT

In article <8t1g69$6m5$>,
Matthew F Funke <> wrote:
>     I'm not well-versed enough in materials science to know if we have
>stuff that would make for a more efficient/thinner suit than the bulky
>Apollo one.  If we had to go back to the Moon again, could we get away
>with more efficient suits?  How much better would they be with today's
>suit-stuff?  How about Martian suits?

There is lots of *potential* for better suits, but not much work has been
done to explore the detailed engineering.  (The shuttle suits use Apollo
suit technology.)

A Moon suit designed today with off-the-shelf suit engineering would be
very much like an Apollo suit, with only detail improvements.

Designing a Mars suit with off-the-shelf technology actually turns out to
be rather a challenge.  The Apollo suits are too heavy.
Microsoft shouldn't be broken up.       |  Henry Spencer
It should be shut down.  -- Phil Agre   |      (aka

From: (Henry Spencer)
Subject: Re: Mars (probably off Topic!)
Date: Tue, 24 Oct 2000 15:50:45 GMT

In article <dY2J5.902$>, RP <> wrote:
>With a very low atmospheric pressure (1% or so) wouldn't there be a lack of
>efficiency in heat transfer to the surrounding atmosphere from the
>astronaut's body/suit?  In other words, what might require very thick
>insulation on earth at 0 celsius would actually require much less on Mars.
>Or no?

Mars's atmosphere is just thick enough to be a nuisance, actually -- it
removes some heat, and makes standard space MLI (multilayer insulation)
not work, but it may not be thick enough to handle all cooling.
Microsoft shouldn't be broken up.       |  Henry Spencer
It should be shut down.  -- Phil Agre   |      (aka

From: (Henry Spencer)
Subject: Re: Mars Dust on Spacesuits
Date: Tue, 24 Oct 2000 15:53:04 GMT

In article <8t48lo$742$>,
Matthew F Funke <> wrote:
>>- the ITMG was white to reflect sunlight, not just to look nice, so when too
>>much dust became ingrained in the outer fabric...
>     I imagine that white also helped in terms of preventing black-body
>radiation of heat.  Yes?  Or would this effect be too little to worry
>about on EVA suits?  (How about the effect on spacecraft?)

In general, the problem with a well-insulated suit is cooling it, not
heating it.  An astronaut -- especially an astronaut working hard moving
around and doing things in a heavy, stiff suit -- generates a lot of heat.
Microsoft shouldn't be broken up.       |  Henry Spencer
It should be shut down.  -- Phil Agre   |      (aka

From: (Henry Spencer)
Subject: Re: Glorious -- but uncomfortable?
Date: Mon, 20 Nov 2000 03:15:45 GMT

In article <djWR5.1394$>,
Doug... <> wrote:
>-  Defecating in zero-G was such an uncomfortable hassle that many Apollo
>crewmen determined to "hold it in" and avoid the process...

I don't recall anyone other than Bill Anders doing that.  The process
wasn't so much uncomfortable as lengthy and tedious (the cleanup, not the
defecation itself, was the problem).

>Extended periods in zero-G cause sinuses to clog, and there's no such thing
>as "a side" to lay on.  Constant nagging sinus pressure?  Not fun.

As I understand it, the clogging generally only lasts two or three days,
until the body has reached a new fluid balance.  So it would be largely
cleared up by the time of a moonwalk.

>-  Space suit gloves worn for seven hours while operating lunar surface
>equipment = bleeding fingernails that have been pulled back from the quick.

Sometimes, and sometimes not.  Depends on the glove fit and the person.

>-  Space suit arms that make you fight against them just to move.  Resulting
>in arms so tired and sore that they would cramp for hours after an EVA.

Again, depends somewhat on the person.  The most successful moonwalkers
were the ones who treated the suit rigidity as a serious problem and made
a real effort to build their arm and hand muscles up ahead of time.

>-  All of the above, plus excitement and a total lack of comfortable
>positioning, resulted in a total lack of ability to get good sleep...

As I understand it, the later crews actually did fairly well on this, once
they got hammocks and suits which could be taken off.  The first few
landing crews did have a real problem getting adequate sleep.
When failure is not an option, success  |  Henry Spencer
can get expensive.   -- Peter Stibrany  |      (aka

Index Home About Blog