Human vs. Robot Explorers! An Easy Debate to Win!

"Fred J. McCall" wrote in message
...
Note the difference. A human can cover in a day what a rover took
FIVER YEARS to cover.

A PLSS backpack is good for 7+ hours. Even if you assume the suited
human can only walk 1 MPH he can pretty much walk back to the landing
site from where either rover is AFTER FIVE YEARS.

Yeah, people are obsolete in space, all right.

Incredible, isn't it? Unmanned landers/rovers are lower cost, but they're
still far less capable than a man in an EVA suit.

Also, I'd like to note that if new missions use pressurized rovers, the
distance traveled from the lander can be far greater than on an
unpressurized rover because the pressurized rover becomes your safe haven.
This does require more than one rover for redundancy, but the ability to
perform multiple EVA's away from the lander would be a huge improvement over
a single unpressurized rover based EVA's which are limited to walking
distance from the lander in case the single rover breaks down.

Jeff
--
"Take heart amid the deepening gloom
that your dog is finally getting enough cheese" - Deteriorata - National
Lampoon

Jeff Findley wrote:

Also, I'd like to note that if new missions use pressurized rovers, the
distance traveled from the lander can be far greater than on an
unpressurized rover because the pressurized rover becomes your safe haven.

There's the atmosphere problem if you go that route though; I assume you
want the crew to EVA from the rover, and if you use a oxygen-nitrogen
atmosphere like on the Shuttle, they will need to prebreath oxygen
before an EVA or get the bends - unless you use a hardsuit full pressure
concept, and then the life support gets involved over the simple low
pressure pure oxygen set-up
Go pure low-pressure O2 in the rover itself and you have a potential
fire hazard.
Go full pressure helium-oxygen and you avoid both the bends on getting
into the low pressure EVA suit and the fire problem, but they end up
sounding like UFO's Purple Haired Moon Ladies.

Pat

"Pat Flannery" wrote in message
dakotatelephone...
Jeff Findley wrote:

Also, I'd like to note that if new missions use pressurized rovers, the
distance traveled from the lander can be far greater than on an
unpressurized rover because the pressurized rover becomes your safe
haven.

There's the atmosphere problem if you go that route though; I assume you
want the crew to EVA from the rover, and if you use a oxygen-nitrogen
atmosphere like on the Shuttle, they will need to prebreath oxygen before
an EVA or get the bends - unless you use a hardsuit full pressure concept,
and then the life support gets involved over the simple low pressure pure
oxygen set-up
Go pure low-pressure O2 in the rover itself and you have a potential fire
hazard.

Not so much. Pure O2 at the pressures used in the suits isn't that much of
a fire hazzard. That's essentially what the Apollo CM did. The problem
with the Apollo 1 ground test was using pure O2 at *far* higher pressures
than would be used in space.

Go full pressure helium-oxygen and you avoid both the bends on getting
into the low pressure EVA suit and the fire problem, but they end up
sounding like UFO's Purple Haired Moon Ladies.

That's another way to solve the problem. Just stick a voice changer in the
communications system to fix that little problem. ;-)

Jeff
--
"Take heart amid the deepening gloom
that your dog is finally getting enough cheese" - Deteriorata - National
Lampoon

Jeff Findley wrote:

Go pure low-pressure O2 in the rover itself and you have a potential fire
hazard.

Not so much. Pure O2 at the pressures used in the suits isn't that much of
a fire hazzard. That's essentially what the Apollo CM did. The problem
with the Apollo 1 ground test was using pure O2 at *far* higher pressures
than would be used in space.

They went with the mixed gas at launch, transition to low pressure pure
O2 during flight system on Apollo as it was possible to do it without
greatly modifying the life support system after the Apollo 1 fire.
But when it me time to design the Shuttle, it was mixed gas during the
whole flight right from day one.

Go full pressure helium-oxygen and you avoid both the bends on getting
into the low pressure EVA suit and the fire problem, but they end up
sounding like UFO's Purple Haired Moon Ladies.

That's another way to solve the problem. Just stick a voice changer in the
communications system to fix that little problem. ;-)

I'm trying to remember If I've ever heard a high-pitched voice woman
talk in a He/O2 gas mixture...that must be damn near ultrasonic.... oh,
Jane Wiedlin...
Regarding the suits, I think they will almost certainly end up using
hardsuits due to the severe abrasive wear that the Apollo fabric suits
experienced from the lunar dust, so maybe the mixed oxygen/nitrogen at
full pressure can be used with good suit design and lots of rotary
joints to keep the volume constant. Gloves built like that would really
be something to see; the Apollo spring steel strips in the gloves to
precurl your fingers against the air pressure and that also detached
your fingernails are obvously not the ideal solution.
God help you if you get a puncture in your full pressure hardsuit
though, as the sudden drop in pressure is going to cause a case of the
bends as the nitrogen in your blood boils - and that's the last thing
you need when trying to patch the leak.
One problem we discussed in relation to the EVA suits in the past was
dragging back dust on them into a pressurized environment where it can
be breathed in by the crew. It's best if the suits remain attached
outside the rover and are entered and exited via hatches in their
backpacks that mate with some sort of "docking collar" on the exterior
of the rover to keep the dust out of its interior.
There's one instinctive thing the astronauts are going to have to be
taught _not_ to do while on EVA, and that's attempt to wipe dust off of
their faceplates - as that will scratch the hell out of the plastic and
make it hard to see through in future use. Maybe a can of compressed gas
can be carried to blow the dust off of the faceplates, like is done with
delicate dust removal from optics here on Earth.


Pat