The other night I was talking with my daughters about exploring Mars. I was telling them about the Viking landers, the Mars Rovers, and I was showing them all the cool pictures that have been returned by the orbiters. So my oldest daughter asks me “what’s next?” and I told her we were getting ready to launch a new orbiter called Mars Atmospheric and Volatile EvolutioN or just MAVEN for short. She sat and thought about it for a second and then asked “so what’s it going to photograph?” I answered “nothing – it has no cameras”. The two of them in unison replied “that’s stupid!” with the younger one continuing “why would you send something all the way to Mars if your not going to take any pictures?” Then they both scampered off to watch Vampire Diaries leaving me alone to ponder the question.
Now anybody who has followed my work knows that Mars has a special place in my heart and the idea that we were sending a probe to Mars without a camera did not sit well with me. I mean, you guys couldn’t have stuck a little one on there just to give us common folk something to look at? But to understand why MAVEN has no cameras you first need to understand why MAVEN is being sent to Mars. MAVEN is going to Mars to explore something that for the most part no longer exists – the Martian atmosphere.
To date, every other spacecraft that has successfully visited Mars has been designed to explore the Martian surface. MAVEN is different, it’s not even going to look at the surface; it’s going to look at the air. You see there is a great deal of mystery when it comes to the Martian atmosphere. Based on findings from NASA’s Curiosity Rover we now know with certainty that Mars was once a habitable world with a thick atmosphere, temperate climate, and large bodies of liquid water on the surface. But today the atmosphere is thin –very thin. It’s so thin that if you stood on the surface your feet would be one temperature and your head perhaps 50 degrees F colder! So what happened? How did Mars change from a habitable world to a frozen desert? Could it happen here on Earth? That’s what MAVEN is going to find out.
There are many theories about why Mars is the way it is. Some say that it’s locked in a global ice age and as a result the atmosphere has frozen to the surface - eventually it will though out and become habitable again. Others say that Mars has died. That the core has cooled and the volcanoes have shut down. Without volcanism the atmosphere could not replenish itself and it simply leaked off into space - never to return. There are other theories about what happened on Mars but there seems to be one central theme. Something happened and the atmosphere became much thinner than it once was. Find out what happened to the atmosphere and you will know how Mars changed from a habitable world to the one we know today. This is why MAVEN has no cameras – what are you going to photograph - the air?
Instead of cameras, NASA has provided MAVEN with a small arsenal of scientific instruments that can see things that no camera could ever detect. It has a Neutral Gas and Ion Mass Spectrometer, an Imaging Ultraviolet Spectrograph, a device to measure Solar Energetic Particles, a Solar Wind Analyzer, a Solar Wind Electron Analyzer, a device to measure the Super Thermal and Thermal Ion Composition of the atmosphere, a device called Langmuir Probe and Waves, and a Magnetometer.
Now I don’t know about you but when I see all those big words strung together like that my brain starts to hurt and I feel a little stupid. But it’s not as intimidating as it may seem. Scientists just like to be real descriptive and as a result they often crank out names that are real long and often confusing to the lay person. Basically all of these “things”, taken as a whole, will act as MAVEN’s cameras except instead of creating photos they are going to produce data with each data point acting like a pixel in a photograph. Put enough of them together and a picture emerges of something that hasn’t existed for a billion years – the missing Martian atmosphere.
For example, you will notice that MAVEN carries with it three instruments that will explore the solar wind – the Solar Energetic Particle experiment, the Solar Energetic Particles device, and the Solar Wind Ion Analyzer. The solar wind is a stream of charged particles that flows off the surface of the Sun as a result of solar storms. Earth is protected from the solar wind by its magnetic field but Mars has no magnetic field so this wind hits the planet and gradually strips away its atmosphere. By studying the solar wind at Mars scientists can calculate just how fast the atmosphere is being stripped away. This allows them to calculate how much atmosphere disappears each year. Once you know how much is disappearing each year, you can simply work backwards to figure out how long ago it was thick enough to support water on the surface. You have just painted one part of the picture. The other instruments will fill in the rest.
This is a part of Mars that has never been explored before and the results promise to revolutionize our thinking about our somewhat older and smaller sister. Mars is unique amongst the planets in that it is the only world that we can conclusively state was once Earthlike. This makes it a very special place in that it is the only world where we can make a direct comparison to Earth - one habitable world to another. It offers us a unique cosmic laboratory where we can study how the Earth once was and, quite possibly, what it one day may become. The more we learn about Mars, the more we learn about ourselves and this is the reason we need to send MAVEN to Mars – even without a camera.