Posted
on October 24, 2015
Did
you know that there is a record-breaking bit of technology circling
around Mars right now?
NASA's
2001 Mars Odyssey is the longest-surviving,
continuously-active spacecraft in orbit around a planet other than
Earth.
As of today, Mars Odyssey has been circling Mars exactly 14 years!
Of
course, we are talking about Earth years. As you know, Earth circles around the
Sun in about 365 days. And of course, that's Earth days.
But
today's record-breaking historical anniversary is all about a satellite circling Mars, not Earth, so maybe we should be
talking about the Martian year and day -- not Earth years and days.
The
Martian day (the amount of time it takes for Mars to rotate once on
its axis) is just a little bit longer than Earth's day. To be more
specific, one Martian day, which is called a sol, is about 2.7% longer than one Earth day.
To
be even more specific:
an
average Martian day is 24 hours, 39 minutes, and 35.2 seconds long
- whereas an average Earth day is (of course) 24 hours long
(Mars, like Earth, has a tilted axis, and so most parts of Mars have days that differ in length, according to hemisphere and therefore season, just as most parts of Earth have days that differ in length through the year. On both planets, days / sols are longer in the summer and shorter in the winter. That's why I gave the AVERAGE Martian and Earth day lengths.)
Many
Earth scientists and engineers who work on Martian missions use
“Mars time” for those missions. Mars time, in this case, would the “local time” of wherever the exploratory
vehicle is located. In Mars time, seconds, minutes and hours are all 2.7% longer
than those time units are here on Earth. Some team members even have wristwatches calibrated to Martian time.
The
Martian year is a lot longer than Earth's year, because of course Mars is a lot farther away from the Sun and the planet has to travel a much larger orbit. The amount of time it takes for Mars to revolve
aaaaalllllll the way around the Sun is almost 687 Earth days, which
translates to about 668.6 sols.
So that means that the Mars Odyssey has been circling Mars for
4,976 sols, or almost seven and a half Martian years.
The
primary mission, the plan, was for the Odyssey to function for
1,007 sols. So it's lasted almost five times longer than the plan.
Hooray for great engineering!!
What
has the Mars Odyssey been doing all these years?
 |
| The label "MARIE," above, refers to the radiation detecting spectrograph. |
The
spacecraft has been using spectrometers and a thermal imaging system
to detect evidence of past or present water and ice, to study the
planet's geology, and to study the planet's radiation environment. It
has also acted as a relay for communications between rovers and
landers and Earth.
Speaking
of water on Mars...
Last
month NASA released evidence that liquid water
sometimes still flows on Mars!
Speaking
of the 2001 Mars Odyssey...
There
is a very famous movie called 2001: A Space Odyssey. The
screenplay, and the book based on the movie, were written by
scientist and science fiction author Arthur C. Clarke. This
spacecraft was named to honor Clarke, his visionary fiction, and of
course his influential movie.
Speaking of movies...
Have
you seen the movie The Martian? It's really good! (It's rated PG-13,
mostly for strong language.)
Also
on this date:
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