The Martian Festival of 2187
Eric Werme USSG
following several years ago (looks like 1987) after the folks at
MacDonald Observatory stopped posting their Stardate series to the
net. A lot of us were rather fond of the daily postings, even though
the slot for the radio commercial message never fit in the
commercial-free USENET postings.
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The Martian Festival is held each vernal equinox. More about the events
on Deimos -- after this.
March 32, 2187 The Great Escape
What good is a moon that's 15 km long - on it's longest axis? About the only
use found so far is athletics. For several Earth decades now, Martian
immigrants have been finding fascinating ways to take advantage of Deimos'
low gravity. On each Martian vernal equinox, the whole solar system turns
it attention to the Great Escape.
This year's Escape has several events:
The Classic
The original jump-off-the-moon event. Deimos' escape velocity is too high
for all but a few athletes to jump off without a running start. The winner
is the person to attain the highest terminal velocity.
The Precision Jump
Several targets have been set up on Deimos for this event. Entrants
choose two targets and jump from one to the other. Deimos's odd shape
has made this one of the favorite events. Points are awarded on
accuracy and landing style, and are multiplied by a difficulty factor
for their jump. Three jumps are made with the sum being the final
score.
The Long Jump
Here the goal is to jump the highest - and return. The winner is the person
who stays off Deimos the longest time. Entrants who reach escape velocity
are disqualified.
The Low Jump
You can't jump directly into orbit because your trajectory will bring
you back to your starting point on the surface. In this event, entrants
take a running start and jump into a shallow climb. Somewhere along the
trajectory they throw a pair of hand-held weights to gain a little more
speed and inject themselves into a low orbit. The winner is the entrant
whose orbit has the shortest period. Entrants are disqualified if they
touch Deimos after their jump or if they throw their orbit injection
weights into orbit (hard to do, but you really don't want to free fall
into one!) Since the winning orbits are around Deimos' longest axis,
officials require everyone to jump in the same direction.
The Relay
This is the only team event. The object is to move a "baton" around Deimos
faster than orbital dynamics of free fall would allow. Contestants put
themselves into highly elliptical orbits in the same plane, but shifted by
a large angle. They're timed so that a contestant heading out meets a
teammate heading in. The baton has a guidance computer that controls a
small thruster. The outbound contestants throw the baton to the next person
and the baton rendevous with him. Therefore, the baton passes between
people moving at speeds well above the circular orbit velocity. Each year
race officials further limit the amount of propellant, thereby increasing
the importance of accurate orbits and good passes. Despite the annual
outcry from contestants, a new record has been set each Escape.
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The officials in charge of the Great Escape report that they have selected
a new company to provide rescue beacons to the participants. Along with
several more recovery vehicles, they are confident that last year's debacle
will not be repeated.
Script by Ric Werme, content by Werme and Dave Spain.
(c) Copyright 2187 McAuliffe Observatory, Olympus Mons, Mars
Addendum - Vital statistics of Deimos
Dimensions: 10 x 12 x 15 km
Density: 5.521 g/cm^3 (Most recent measurement)
[Deimos' odd shape helps make the Great Escape the favorite part of
the Martian Festival. However, it plays havoc with computing the
gravitational field. Therefore, the following calculations have been
done for a sphere 12 km in diameter.]
Escape velocity: 10.5 m/sec
Low altitude orbital velocity: 10.5/sqrt(2) m/sec
Period of above orbit: Easy, do-it-yourself calculation
:-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-)
A Pretty Realistic Ric Werme
& Informative Look uucp: decvax!linus!alliant [RIP]
Focused On Olympic Leaps Phone: 603-673-3993
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PostScript:
I had hoped to inspire a lot of discussion about this, and expected that once
people calculated the period of an orbit around Deimos, they would note
that it, 90 minutes, seems surprisingly close to that of a low Earth
satellite. Indeed, the density I used is that of the Earth's, and much
to my surprise, the period of a low orbit does not depend on the larger
body's size. (You were expected to notice that listing the density to
four places was a bit much!) Apparently we *do* know the density of Deimos,
and it's only about 60% of Earth's. I assume that was learned from the
deflection of the <I forget> spacecraft that photographed Deimos. I've
never had a chance to update the text with the new figure.
Asteroid Ida is about twice the size of Deimos (and hence about 8 times the
volume). You won't be able to jump off of Ida, but you ought to be able to
shoot an arrow at its moon. Lessee, if we name its moon Ho, we could write
about the Ida hoe-down, a blue grass festival held in Potato country.
(And next to the Big Sky state?) Needs work....
--
Eric (Ric) Werme | we...@zk3.dec.com
Digital Equipment Corp. | This space intentionally left blank.