365daysDate: June 14, 2009

Title: The Mars Global Surveyor


Podcaster: Nancy Atkinson

Organization: Universe Today:
Nancy’s website:

Description: For almost a decade, the Mars Global Surveyor sent back information from its orbit around Mars. To celebrate this landmark mission, Nancy provides information and an original song about the little spacecraft that has changed the way we view the Red Planet.

Bio: Nancy Atkinson writes daily for Universe Today, is on the production team for Astronomy Cast, and is part of the IYA New Media Working Group, helping to bring this podcast to you every day of 2009. She also is a NASA/JPL Solar System Ambassador.

Today’s sponsor: This episode of 365 Days of Astronomy is sponsored by Clockwork Active Media.


Hi, this is Nancy Atkinson, writer for Universe Today I’d like to talk about one of my favorite space missions, the Mars Global Surveyor. In my opinion, MGS was a landmark mission. While this Mars-orbiting satellite is no longer functioning, it had a long life – the longest mission to Mars so far – and it discovered so many amazing things. But most importantly, MGS changed the way we think about Mars.

Earlier missions to Mars were very brief missions, mostly flybys, and even though the Viking Landers were very successful and sent back thousands of pictures from Mars’ surface, we still thought of Mars as a dry, cold and dead world. But MGS changed that. We now know that Mars is a very dynamic planet, with seasonal changes and geologic activity.

MGS launched in November of 1996, arriving at in Mars September, 1997.

The mission started out precariously, however. MGS was one of the first spacecraft to use aerobraking, where instead of using onboard thrusters and propellant, the spacecraft dips into the atmosphere to gradually slow itself down and make adjustments to its orbit. So, aerobraking is kind of like using the atmosphere as both a brake and a steering wheel. But, one of the solar panels was jammed and didn’t lock into position correctly. If the aerobraking maneuvers were carried out as planned, the solar panel might have been damaged or even broken off, which would likely meant the end of the mission. So, the aerobraking was done in a slower manner to save the solar panel. This meant the maneuvers took longer, and so the planned science observations didn’t get started as soon as hoped.

But the wait was worth it. The Mars Obiter Camera ( or MOC) returned over 240,000 images. This formed a data set that will likely be studied for decades. But the camera, designed by Michael Malin, also gave us a new view of Mars, showing it to be a very beautiful, if not photogenic planet. Not only did we get a better look at the huge volcanoes on the Red Planet, but now we saw frost covered dunes, mysterious ice pits, ancient river beds, heart shaped and smiley face craters and details of tremendous canyons bigger than anything here on Earth. You can spend hours looking through all incredible images, and find features that look gigantic worms, sheep in a pasture, a forest covered by snow, or almost anything the imagination can conceive.

MGS’s long life also allowed it to track changes taking place on Mars. Since the camera was able to take duplicate images years apart of several regions on Mars, before-and-after images showed new gullies on hillsides, and also new deposits in gullies seen earlier, suggesting that perhaps liquid water carried sediment through the gullies.

We were also able to track Mars through repeated annual cycles, which revealed how the carbon dioxide ice at the poles grows and recedes each season.

Another instrument, The Mars Orbital Laser Altimeter, or MOLA produced an unprecedented global topographic map of Mars, including 3-D views of the polar ice caps. The instrument revealed a multitude of highly eroded or buried craters too subtle for previous observation including a gigantic impact that created Hellas Basin.

The Thermal Emission Spectrometer or TES, used an infrared spectrometer to map minerals and found concentrations of hematite, a mineral that often forms under wet conditions. It found a huge area of hematite in the Meridiani Planum region, which is why that area was chosen as a landing site for the Mars Exploration Rover Opportunity.

Another instrument The Magnetometer/Electron Reflectometer called MAG/ER for short, found localized strips of left-over magnetic fields, indicating that Mars once had a global magnetic field like Earth’s, which would have shielded the planet’s surface from deadly cosmic rays in Mars past.

And experiment called the Radio Science Instruments recorded the weather on Mars, providing a daily “weather report” and recording seasonal patterns of clouds and dust within the atmosphere over the entire planet.

Beyond the investigations with its own instruments, MGS provided support for other Mars missions, including landing-site evaluations, communication relays and imaging of other spacecraft, both in orbit and on the surface.

MGS operated in orbit around Mars for nine years and 52 days. Engineers nursed the spacecraft through several problems, including a failed gyro and a worn-out reaction wheel. But in the end, MGS appears to have succumbed to battery failure caused by a complex sequence of events involving the onboard computer memory and ground commands. And likely, the solar panel that caused problems so many years ago may have been part of the problem of the battery failure.

But MGS lasted longer than anyone ever predicted, and its mission was extended three times.

However, MGS isn’t dead. She lives on with the all the data she purveyed that will keep scientists busy for years. The view that MGS gave us is that Mars an ever-changing planet with its own unique, strange and complex history, and her observations have and will continue to inspire and shape our future explorations of Mars.

Speaking of inspiration, in the last podcast I did on April 20, I shared how when I get inspired by something, I like to write music about it. MGS has inspired me to write a song, and I’d like to share that with you today. It tells the story of the MGS – and just like NASA, I use a few acronyms, but I hope I’ve explained them all in this podcast. But anyway, I hope you enjoy the song and that helps you appreciate the fantastic mission of the Mars Global Surveyor.

By Nancy Atkinson

(Special thanks to Mike Spainhour for playing keyboard and percussion, as well as recording and mixing.)

In ten years of discovery, MGS left us all a legacy
We thought it was a dry, dead world
But now it seems
There’s a landscape of dynamic extremes.

From Hellas Basin to Candor Chasma
To the grabens on Pavonis Mons
There’s new fresh gullies and now we know
There’s magnetic stripes, hematite and debris flow

Oh, the wonders we’ve seen through Malin’s eyes
Canyons, riverbed, storms
It’s a Mars no longer disguised.

It’s a noble purveyor
It’s the Global Surveyor
And it’s changed the way we see Mars.

She was coming in on a wounded wing
So we changed the way of aerobraking
MGS overcame adversity
And she became a model of longevity.

Oh, the wonders we’ve seen
Through MOLA’s eyes
Ice caps, chasms, craters
It’s a Mars no longer disguised.

It’s a noble purveyor
It’s the Global Surveyor
And it’s changed the way we see Mars.

Oh, the wonders we’ve seen
Through Malin’s eyes
Rockfalls, clouds, auroras
It’s a Mars no longer disguised.

It’s a noble purveyor
It’s the Global Surveyor
And it’s changed the way we see Mars.

Copyright Nancy Atkinson 2002, 2009

End of podcast:

365 Days of Astronomy
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