On Jul 30, 2009, at 11:41 AM, Stephen A. Lawrence wrote:
Horace Heffner wrote:
Just to complete my thought.
On Jul 28, 2009, at 5:02 PM, OrionWorks wrote:
"We should go boldly where man has not gone before – fly by the
comets, visit asteroids, visit the moon of Mars. There’s a monolith
there. A very unusual structure on this little potato shaped object
that goes around Mars once in seven hours. When people find out
about
that, they’re going to say "Who put that there?" Well, the universe
put it there. If you choose, God put it there."
Mars has *two* moons, Phobos and Deimos. Strange he would make that
mistake.
Since the larger, Phobos, has an orbital period of 7.66 hours, he
must
be talking about that one. It certainly is small, diameter 22.2 km.
Not much energy required to adjust the orbit of a very low flying low
speed robotic survey satellite so as to photograph every
centimeter of
it in 3D from multiple angles, and then land for close inspection.
See:
http://en.wikipedia.org/wiki/Moons_of_Mars
Phobos has a mass of 1.08 x 10^16 kg, and radius of 11.1 km. At
surface
grazing altitude, a robot satellite would have a velocity v given by:
v = ((G M)/r)^0.5 = 8.06 m/s
That's about 18 miles per hour, bicycling speed. Orbital period P is:
P = (2 Pi r)/v = 8653 seconds
That's about 10 orbits per earth day. Using laser ranging it
should be
possible to develop precise surface contours and identify surface
gravitational variations. Then close flybys and photography of any
surface feature can be made in 3D. Using solar power and ion
rockets,
orbits can be adjusted for close flyby to any location.
Communications
can be handled via link with existing Mars communications relay
facilities. As these kinds of missions go, this one could be
comparatively cheap. The problem is actually knowing there is
something
there to make the mission worthwhile.
And what if there *is* a monolith there. How to communicate with it?
"Monolith: n : a single great stone (often in the form of a column or
obelisk)"
Outside of certain stories by Clarke, "communicating with" a
monolith is
not just difficult -- it's impossible. Rocks are notoriously
uncommunicative.
That is a religious issue, and clearly off topic. 8^)
Note that, at least in the quoted text I've seen, Aldrin didn't say
anything to imply that the "monolith" was more than an unusually
shaped
hunk of rock, nor did he say anything which implies it's more than a
visual curiosity. Certainly he said nothing which would imply
attempts
at communicating with the monolith would be more productive than
attempts at communicating with, say, a swivel chair.
I don't recall anyone ever saying, and it would be extremely odd if
anyone said about their swivel chair: "... the universe
put it there. If you choose, God put it there." So, I am lead to
deduce that either Buzz Aldren is just putting a spin on things to
generate interest in manned exploration, or he and Sir Aurthur knew
something we don't about monoliths on moons. As I alluded to in my
post, all the stuff about monoliths could be pure fantasy. What I
find cool is the energy efficiency and slow speed with which one can
fly about a 22 km diameter rock.
Best regards,
Horace Heffner
http://www.mtaonline.net/~hheffner/
