Human factors, technology and deep space missions

[Astronuc]

When a Mars Simulation Goes Wrong​

https://www.theatlantic.com/science/archive/2018/06/mars-simulation-hi-seas-nasa-hawaii/553532/

The article came across my desk (computer screen). Human behavior is complicated.

I'm more interested in the technical side of space travel, specifically the propulsion system. I'll let others worry about the crew and crew issues. However, I have to wonder about decisions on the part of some that put mission over persons.

Certainly, better planning is required. Contingencies need to be considered and plans developed. Afterall, we've been thinking about manned missions to Mars for decades, even before we landed persons on the Moon.

It generally takes about 5 to 20 minutes for a radio signal to travel the distance between Mars and Earth, depending on planet positions.

https://mars.nasa.gov/mars2020/ spacecraft /rover/communications/

Edit/update: https://www.hi-seas.org/, The Hawai‘i Space Exploration Analog and Simulation (HI-SEAS)

 

[gmax137]

Thanks for the link, @Astronuc That's an interesting read, I was not aware of the program.

Coincidentally I was vacationing on the Big Island last month and drove up past the Pohakuloa Training Area and up to the observatory visitor center. It feels pretty isolated even though Hilo is less than an hour drive.

 

[Astronuc]

I find such articles interesting. About years ago, we were considering missions to Mars from the standpoint of energy and propulsion requirements. I was on a team that looked at a nuclear-electric propulsion system, and my focus was the core design: structural materials, fuel, and core operating conditions, the NPP (core, heat transport/transfer, power conversion systems), and ultimately the propulsion systems. The integration of the power plant into the mission was complicated.

One interesting aspect was considering system faults, e.g., a reactor/plant trip and how things shutdown and for how long, and at what point is a transfer orbit recoverable vs unrecoverable (how long can a craft coast at various points in a mission and what it would take to recover), and how the crew would respond. So, one would have to simulate a range of mission scenarios, and how the system/mission would evolve with various faults, and how much margin would be necessary. It's much the same as a fault analysis tree for a conventional NPP, but the ramifications are different. Nobody wants to lose a crew, as nobody wants a reactor trip or accident.

That's one reason that unmanned craft are preferred for current missions.

 

[gmax137]

Maybe these considerations help understanding why US Navy submarine crews are over 100 sailors. I was surprised that the Mars mission simulation studies were looking at a crew of only six.

Obviously the Mars payload scales with crew size, but it doesn't take too many things going on at once to overwhelm six people.

 

[256bits]

Maybe these considerations help understanding why US Navy submarine crews are over 100 sailors. I was surprised that the Mars mission simulation studies were looking at a crew of only six.

Obviously the Mars payload scales with crew size, but it doesn't take too many things going on at once to overwhelm six people.

People redundancy, along with system.
24 hour coverage in times of crisis.

What is the best amount of crew - 6 , 60, 600?
One can see that as the amount of people increases, attrition of members has less and less effect upon mission completion. Of course, turnover acquired from a general population is not possible in a remote setting, but would have to be accomplished by bringing along a 'superfluous' mini population that can fill gaps as need be.
It can get quite expensive quickly if one wants to eliminate people malfunction from the risk calculation for mission success.

 

[Hornbein]

People redundancy, along with system.
24 hour coverage in times of crisis.

What is the best amount of crew - 6 , 60, 600?
One can see that as the amount of people increases, attrition of members has less and less effect upon mission completion. Of course, turnover acquired from a general population is not possible in a remote setting, but would have to be accomplished by bringing along a 'superfluous' mini population that can fill gaps as need be.
It can get quite expensive quickly if one wants to eliminate people malfunction from the risk calculation for mission success.

Remember the Zumwalt class destroyers? One of the biggest failures of military procurement (if you consider spending large sums with no result failure). One of the big cost savings was supposed to be a small crew, 150 or so. But then what does the ship do when there are casualties?

 

[Astronuc]

NASA has limited experience. The furthest manned missions were to the Moon, with Apollo spacecraft and a crew of 3. Those missions were relatively simple compared to a mission to Mars (a lot longer and much farther).

For a manned mission to Mars, a support system (something like Skylab, but with a lot more shielding) should be sent in advance. An earth-to-Mars transfer vehicle would also require more shielding. One proposed design used cargo (including water) and propellant (in tanks) as shielding, and possibly a magnetic field. The problem with a magnetic field is the radiation (charged particles) where the magnetic field lines converge.

Another challenge is the propulsion system, which in the past was considered to be nuclear, with a choice of short duration (a few days) direct nuclear thermal or continuous by a nuclear electric system, or a hybrid system. There are challenges with all systems.

 

[berkeman]

When a Mars Simulation Goes Wrong​

https://www.theatlantic.com/science/archive/2018/06/mars-simulation-hi-seas-nasa-hawaii/553532/

WITW? How can a structure built in Hawaii have an electrical installation that is not up to NEC wiring code? That's baffling to me.

Stojanovski said she suspects the electric shock may have occurred because the crew member’s fingers brushed against live wiring. “In a regular household circuit breaker, you have a safety panel that covers all the live wiring that’s behind the switches,” Stojanovski said. “Unfortunately, our circuit breaker didn’t have one of those.”