Nat Geo Mars...Some Thoughts...Spoilers

Besides being a commercial for Space X, which honestly I have no trouble with, it was ok. Better than Hollywood's problems solved in two hours or less, but I did not appreciate the false dramatic manufactured moments.

Top of the list is the emergency exit door to a vacuum that opens OUTWARDS! (Ranks just below Matt Damon's duct tape patch.)

Second is the "fall" the commander takes in the opener. Trying to climb a ladder against several G's is begging for a cracked skull.

Third is the last minute discovery of a "usable" lava tube, at the last 3 meters of the single longest cable we made out of our last 3 cables...

And the 4th is the show closer. You just knew they were going to find it didn't you?

But actually a reasonably technical presentation of the issues with a Mars. I especially like the Van Braun tie in during the last two episodes.

CRC wrote:Besides being a commercial for Space X, which honestly I have no trouble with, it was ok. Better than Hollywood's problems solved in two hours or less, but I did not appreciate the false dramatic manufactured moments.

Top of the list is the emergency exit door to a vacuum that opens OUTWARDS! (Ranks just below Matt Damon's duct tape patch.)

Second is the "fall" the commander takes in the opener. Trying to climb a ladder against several G's is begging for a cracked skull.

Third is the last minute discovery of a "usable" lava tube, at the last 3 meters of the single longest cable we made out of our last 3 cables...

And the 4th is the show closer. You just knew they were going to find it didn't you?

But actually a reasonably technical presentation of the issues with a Mars. I especially like the Van Braun tie in during the last two episodes.

But the botanist going suicidal over the euthanasia of his seedlings... seriously? Blowing out the airlock and taking part of the habitat with him. The last episode is still unwarched on my DVR.

Haven't seen this but I did watch "The Space between us", last Week. Far fetched as a dramatic flick, but as a Mars flick it is the best I've seen. If you like Space X you should go check it out.

CRC wrote:Top of the list is the emergency exit door to a vacuum that opens OUTWARDS! (Ranks just below Matt Damon's duct tape patch.)

Why would that be a bad idea? I should think that with any kind of air pressure it would be very difficult if not impossible to open the emergency exit if it opened inward.

(much the same principle as waiting for water pressure to equalize before opening a door to escape from a sinking car.)

Weird Harold wrote:

CRC wrote:Top of the list is the emergency exit door to a vacuum that opens OUTWARDS! (Ranks just below Matt Damon's duct tape patch.)

Why would that be a bad idea? I should think that with any kind of air pressure it would be very difficult if not impossible to open the emergency exit if it opened inward.

(much the same principle as waiting for water pressure to equalize before opening a door to escape from a sinking car.)

I suppose it is ok as long as the lock is depressurized after ech use. 35psi on one side and ~0 pressure on the other is begging for a metal fatigue failure. Even a slight warp on a pressure door frame is potentially ... explosive.

WeirdlyWired wrote: I suppose it is ok as long as the lock is depressurized after ech use. 35psi on one side and ~0 pressure on the other is begging for a metal fatigue failure. Even a slight warp on a pressure door frame is potentially ... explosive.

Why would it be any different than a regular airlock? or the hull, for that matter?

And why would a habitat be pressurized to more than twice earth-sea-level pressure anyway?

Weird Harold wrote:

CRC wrote:Top of the list is the emergency exit door to a vacuum that opens OUTWARDS! (Ranks just below Matt Damon's duct tape patch.)

Why would that be a bad idea? I should think that with any kind of air pressure it would be very difficult if not impossible to open the emergency exit if it opened inward.

(much the same principle as waiting for water pressure to equalize before opening a door to escape from a sinking car.)

the problem was that it WAS NOT an airlock. It was a single exit "fire door" to vacuum. One that no one would ever, ever want opened. One touch and BOOM, explosive decompression...

CRC wrote:the problem was that it WAS NOT an airlock. It was a single exit "fire door" to vacuum. One that no one would ever, ever want opened. One touch and BOOM, explosive decompression...

One would hope that it wasn't operated by a "crash bar."

I do very much doubt that it would open to "just one touch." Explosive decompression would be very effective in extinguishing a fire, though.

Weird Harold wrote:

CRC wrote:the problem was that it WAS NOT an airlock. It was a single exit "fire door" to vacuum. One that no one would ever, ever want opened. One touch and BOOM, explosive decompression...

One would hope that it wasn't operated by a "crash bar."

I do very much doubt that it would open to "just one touch." Explosive decompression would be very effective in extinguishing a fire, though.

Mars air pressure = 0.087 psi. Earth air pressure at sea level = ~ 15psi. which is a differential pressure almost 178x.

IIRC every time you increase the air pressure in a vessel by 1 atm you double the volume of air inside it. Amount of air inside a Mars habitat to maintain 178x pressure differential = 2^178V or a good sized jet engine when that door fame warps enough to leak.

Weird Harold wrote:

CRC wrote:the problem was that it WAS NOT an airlock. It was a single exit "fire door" to vacuum. One that no one would ever, ever want opened. One touch and BOOM, explosive decompression...

One would hope that it wasn't operated by a "crash bar."

I do very much doubt that it would open to "just one touch." Explosive decompression would be very effective in extinguishing a fire, though.

Unfortunately, that's exactly what happened. One of the scientists, whom was hallucinating at the time, thought he was opening a door to a field outside his house on Earth. Turned the crank and BOOM, destroyed a significant chunk of the habitat and killed several people.

In a prior episode, they did have a fire in one area and the commander had to physically break a window to decompress and extinguish the fire. (Why not a manual valve on the wall - I don't know.)