October 24 – Mars Orbit? Mission Accomplished!

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:

Anniversary of the discovery of Ariel and Umbriel

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