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| Deletions are marked like this. | Additions are marked like this. |
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| ||<-4)> Orbit Radius (km) || Period||<-2>Orbit Speed,Inclination||<-2> Radius (km) || Mass || Gravity || Escape || | || ||<-3:> Orbit Radius (km) || Period||<-2>Orbit Speed,Inclination||<-2>Body Radius (km)|| Mass || Gravity || Escape || |
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| ||<-12>'''Example Artificial Satellites''' - - - Mars Standard Gravitational Parameter 42828.37 km³/s², period = (r^1.5) / 32.937 || ||<-3> 515 km altitude, 12/sol|| 3901 || 7398 || 3.133 || ||<-3> 2897 km altitude, 6/sol || 6193 || 14786 || 2.630 || |
||<-12> '''Example Relay Satellites''' - - - - - Mars Standard Gravitational Parameter 42828.37 km³/s², period = (r^1.5) / 32.937 || ||<-3> 12/sol, 515 km altitude || 3901 || 7398 || 3.133 || ||<-3> 6/sol, 2897 km altitude || 6193 || 14786 || 2.630 || |
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=== Delays in seconds to farside === ||<-2> ||<-3:> Elevation = 0 degrees ||<-3:>Elevation = 10 degrees||<-3:>Elevation = 20 degrees|| || Station || Relay || Coverage || Hops || Delay || Coverage || Hops || Delay || Coverage || Hops || Delay || || Deimos || 6/sol || 0.4276 || 1 || 0.224 || 0.3439 || 2 || 0.274 || 0.2667 || 2 || 0.258 || || Phobos || 6/sol || 0.3189 || 1 || 0.127 || 0.2342 || 2 || 0.178 || 0.1793 || 2 || 0.162 || || Deimos || 12/sol || 0.4276 || 2 || 0.206 || 0.3439 || 3 || 0.207 || 0.2667 || 4 || 0.205 || || Phobos || 12/sol || 0.3189 || 2 || 0.109 || 0.2342 || 3 || 0.115 || 0.1793 || 5 || 0.130 || |
The View from Deimos and Phobos
The mean radius of Mars is 3389.5 km, varying from 3396.2 km at the equator to 3376.2 km at the poles. This page computes the fraction of a smooth spherical Mars visible from Deimos, Phobos or a single artificial satellite, as a function of elevation angle above the horizon.
The real planet has topography, so the equatorial side of high latitude mountaintops will have more visibility, the poleward sides less, valleys mostly less. An array of relay satellites can offer almost complete visibility, except for the bottom of steep trenches. Temporary relay towers can be placed at the rim of trenches while they are occupied by robots.
Mars exploration will be complicated, but does not require line-of-sight to either Martian moon; not even the Sun if the robots are powered by isotope or fission thermal generators.
With an axial tilt of 25.2 degrees, and a 686.97 (Earth) days per year, Mars will have polar winter darkness times about twice as long as the 23.4 degree tilted, 365.24 days per year Earth. Mars polar surface rovers will spend half their time operating at night, with neither Mars moon visible; some important (and so-far undiscovered) surface phenomena may not be visible at any other time, so relay satellites in high inclination are essential for a complete scientific exploration of Mars. This transforms the question of visibility to which Martian moon provides the lowest round-trip speed-of-light delay to the Martian poles with a smallish number of relay satellites? A Deimos station may be able to see more high-altitude relay satellites.
The Martian moons are approximate ovoids, tide-locked and synchronous with their long axis pointed towards Mars. Important characteristics as manned or "big computation" outposts are:
|
Orbit Radius (km) |
Period |
Orbit Speed,Inclination |
Body Radius (km) |
Mass |
Gravity |
Escape |
||||
|
Periapsis |
Apoapsis |
Semimaj |
(sec) |
(km/s) |
degrees |
Maximum |
Minimum |
(kg) |
gee |
V (m/s) |
Phobos |
9234.42 |
9517.58 |
9376.00 |
27553.8 |
2.138 |
1.093 Mars |
27 |
20 × 24 |
1.066e16 |
5.8e-4 |
11.4 |
Deimos |
23455.5 |
23470.9 |
23463.2 |
109123 |
1.352 |
0.93 Mars |
15 |
12.2 × 11 |
1.476e15 |
3.1e-4 |
5.56 |
Example Relay Satellites - - - - - Mars Standard Gravitational Parameter 42828.37 km³/s², period = (r^1.5) / 32.937 |
|||||||||||
12/sol, 515 km altitude |
3901 |
7398 |
3.133 |
||||||||
6/sol, 2897 km altitude |
6193 |
14786 |
2.630 |
||||||||
Mars day: (sol) |
88775 |
24.077 |
25.19 tilt |
3396.2 |
3376.2 |
6.417e23 |
0.376 |
5027 |
|||
Delays in seconds to farside
|
Elevation = 0 degrees |
Elevation = 10 degrees |
Elevation = 20 degrees |
|||||||
Station |
Relay |
Coverage |
Hops |
Delay |
Coverage |
Hops |
Delay |
Coverage |
Hops |
Delay |
Deimos |
6/sol |
0.4276 |
1 |
0.224 |
0.3439 |
2 |
0.274 |
0.2667 |
2 |
0.258 |
Phobos |
6/sol |
0.3189 |
1 |
0.127 |
0.2342 |
2 |
0.178 |
0.1793 |
2 |
0.162 |
Deimos |
12/sol |
0.4276 |
2 |
0.206 |
0.3439 |
3 |
0.207 |
0.2667 |
4 |
0.205 |
Phobos |
12/sol |
0.3189 |
2 |
0.109 |
0.2342 |
3 |
0.115 |
0.1793 |
5 |
0.130 |