I've spun them slowly to keep them flat - it's clear that Selden is right and you couldn't hang anything from such filmy things without inducing distortions. So they have to be precessed to keep pace with Mars' movement around the Sun - maybe Mars-based lasers could be used to fine tune their position and precession?
If you play with this model, you'll notice the mirrors rising and falling relative to Mars - this is an artefact of the orbit I've used to keep them precisely on the Mars-Sun line, but it may well be realistic, too. As Mars approaches perihelion, the mirrors would be driven outwards (unless they were reefed in some way); at aphelion they'd fall inwards again. Their tilt would need fine adjustment (those lasers again!) to maintain stability and the direction of the reflected light.
A more unfortunate artefact is the libration of the mirrors in longitude - tilting east and west as they follow Mars around the Sun. This is definitely unrealistic, but I can't think of a way to get rid of it, given that Celestia supports only constant rotation and precession rates at present.
Code: Select all
# A pair of Zubrin solettas to help terraform Mars
"MarsMirrors" "Sol"
{
#Mesh "empty.3ds" # An invisible placeholder ...
Color [ 0 0 0 ] #
CustomOrbit "vsop87-mars" # ... at the centre of Mars ...
Obliquity 1.8506 # ... with its equator
EquatorAscendingNode 49.479 # parallel to Mars' orbit
Radius 75 # "Large" enough and "bright" enough to
Albedo 1.0 # prevent Celestia turning off its satellites
}
"#" "Sol/MarsMirrors"
{
#Mesh "empty.3ds" # Another invisible placeholder
Color [ 0 0 0 ] #
EllipticalOrbit # Its "orbit" is a scale
{ # model of Mars' orbit around
Period 686.980 # the sun, lying in the same
SemiMajorAxis 214000 # plane as Mars' orbit, orientated
Eccentricity 0.0934 # the same way, and with the
LongOfPericenter 286.562 # same period
MeanLongitude 305.974 # So it stays precisely opposite the sun
}
Obliquity 90 # On its side, with its
EquatorAscendingNode 40.521 # pole aimed at Mars (90 - 49.479), and
PrecessionRate 0.524032722 # precessing to maintain that orientation
Radius 75 # "Large" enough and "bright" enough
Albedo 1.0 # to prevent Celestia turning off its satellites
}
"NorthMirror" "Sol/MarsMirrors/#"
{
#Mesh "mirror.3ds"
Radius 62.5 # 125km wide
Oblateness 0.999999 # flat disc
EllipticalOrbit
{
Period 1e12 # Essentially fixed in position,
SemiMajorAxis 3392.3 # just under one Mars radius
MeanLongitude 90 # to the north of Mars-Sun line
}
Obliquity 0.91 # Tilted to illuminate
EquatorAscendingNode 180 # Mars' south polar region
RotationPeriod 13.8 # Spin-stabilized, ~0.0001g at rim
Albedo 1.0 # Bright as possible
}
"SouthMirror" "Sol/MarsMirrors/#"
{
#Mesh "mirror.3ds"
Radius 62.5 # 125km wide
Oblateness 0.999999 # flat disc
EllipticalOrbit
{
Period 1e12 # Essentially fixed in position
SemiMajorAxis 3392.3 # just under one Mars radius
MeanLongitude 270 # to the south of Mars-Sun line
}
Obliquity 0.91 # Tilted to illuminate
EquatorAscendingNode 0 # Mars' north polar region
RotationPeriod 13.8 # Spin-stabilized, ~0.0001g at rim
Albedo 1.0 # Bright as possible
}
Grant