On 7/26/2019 12:58 PM, Niklas Holsti wrote:
On 19-07-24 20:18 , wrote:
On Tuesday, May 21, 2019 at 2:15:19 PM UTC-4, Niklas Holsti wrote:
The SpaceX plans for the first Mars trips involve two Starships
making the trip at the same time. The SpaceX videos show a Starship
flying alone, in a fixed attitude (pointing away from the Sun) thus
in free fall. From other sources there is some concern that a
multi-month weightless trip may incapacitate the pilots and
passengers, for example resulting in blurred vision when they are
again subjected to acceleration or gravity. Here I propose a
possible solution: cable the two Starships together in a
nose-to-nose attitude and rotate them to provide simulated gravity
during the trip.

Do you have any numbers on this? How much propellant would be
necessary to spin up the rotation?

Assuming a 50 m radius of rotation and a desired acceleration
(pseudo-gravity) of 3 m/s/s, a rotational speed of about 12.2 m/s is
enough. So quite small compared to orbital velocities.


Have you calculated as to whether it would be necessary to use curved
decks to preserve gravity normal vectors across the entire radius of
deck surface that would be off-axis from the rotation?

I suppose it would depend on the rotational radius. If the radius is
long enough the length of the decks may not matter as they wouldn't
extend far enough to experience any off-axis effects since they are too
small a section of the circumference thus they could remain flat.

Also let's not forget the centrifuge approach ala the movie 2001: A
Space Odyssey. One (or two) sections of the Starship could be put in
(counter)rotation to provide artificial gravity within the section(s).
It does introduce issues of vibration and spacecraft stability. Or even
more simply, just put the spacecraft into a spin along the flight path
vector. Thus no 2nd ship required or fancy rendezvous and un-tether
maneuvers needed. This would also allow incremental build-up of
spacecraft by joining future Starships together in LEO to make a larger
spacecraft.

It's fun to speculate. None of this would be needed for trips to and
from the Moon. The flight is just not that long.

Underlying all of lunar & planetary habitation is the assumption that
the human body does not develop strange new diseases from not being in
1G, or that there is some conditioning (PT) needed near 1G to stave off
these effects. Subsequent generations, if born in that environment might
not need that, but might not be able to comfortably live back on Earth
either. Data points we just don't have right now.

Dave