Rosetta Instrument MIRO: How does it work?

Mark Hofstadter, MIRO CO-I, answers questions about Rosetta’s Microwave Instrument for the Rosetta Orbiter and it’s similarities to it's sister instrument, VIRTIS


Question 1                    

00:04   MIRO stands for Microwave instrument for the Rosetta orbiter.

00:09   It also happens to be the name of a famous surrealist artist who was active in the 21st century.


Question 2:

00:20   The MIRO Instrument measures the radio waves that the comet and all bodies actually naturally give off

00:28   and from this information we learn about the composition, the temperature and the velocity of the gases that are coming off the comet

00:39  We can also study the temperature and properties of the solid nucleus, which is the core of the comet and we’re sensitive to this below the surface maybe  from a millimeter to 10 centimeters beneath the surface.


Question 3: Why is this information important for the rosetta mission?

01:00  We think that comets are left over from the formation of our solar system.

01:05  The planets we see today were built up from smaller pieces like comets  crashing together

01:11  and sticking together over millions of years and forming something big

01:15  So by looking at the composition and structure of comets today, we hope to learn about the building blocks

01:22  and the processes that formed the planet that we live on and see around us


Question 4: How does the MIRO data compare to VIRTIS data?

01:33  The MIRO Instrument using radio waves is sensitive to properties of the  nucleus beneath the surface maybe down to roughly 10 centimeters

01:43  an instrument working at infrared wavelengths like VIRTIS which is also on the rosetta orbiter,

01:48  it’s sensitive to the very top of the nucleus surface

01:53  so comets are very complicated there s  a lot of things going on there are things changing

01:58  so by combining both instruments we get the best picture of what’s going on and by

02:04  combining virtis and miro for exampke we can study the temperature and structure

02:09  of the nucleus from the surface down ten or twenty centimeters and we can look for changes in the nucleus.


Question 4: How does MIRO work?                          

02:22  The MIRO instrument measures radio waves that the comet naturally gives off

02:28  So a lot of people are surprised by that but it turns out that all normal matter,

02:33  everything you see around you gives off radio waves. Your body, a chair, even the sky

2:40  gives off radio waves that a sensitive receiver can pick up

2:46  In understanding how MIRO works there’s just two other things you may want to keep in mind.

2:50  One is something called the electromagnetic spectrum that’s a big word but all   it means is it’s a wave,

2:59  an oscillation of electric and magnetic fields like light.

3:03  We’re all comfortable with light and light has different colors like blue green yellow red,

3:08    light is an electromagnetic wave but your eye is not sensitive to all possible colors of light

03:16  There are colors with longer and shorter wavelengths than your eyes can see

03:21  So for example just beyond the red where your eye is not very sensitive getting to longer wavelengths is something we call infrared

03:31  when you go even longer maybe wavelengths of millimeters to centimeters tens of centimeters we call these radio waves

03:40  So radio waves are just like infrared waves just like visible light waves, they just have different frequencies   

03:47  and our eye is not sensitive to all of them.

3:50 Another thing to keep in mind that you are probably familiar with is the idea 

3:56 that the amount of energy something gives off depends on its temperature. 

4:02 Why do I think that you are familiar with this? Imagine a fireplace poker that's 

4:05 just sitting beside the fireplace and its cool, and it just has this metal grey color. 

4:13 If you stick it in the fire and it starts to heat up, it will start to glow red. If it 

4:18 keeps getting hotter and hotter it will eventually glow white hot. so by 

4:25 looking at the amount of energy that fireplace poker is giving off and 

4:29 it's color, you learn soothing about the temperature. So I said before 

4:34 that radio waves are just like light waves and it is the same kind of idea. 

4:39 The amount of radio energy something gives off is sensitive to its temperature 

4:43 primarily, but also its composition. And so a very fine measurement of the 

4:49 radio energy tells us the temperature and composition of the thing we are 

4:53 looking at, and that basically is how MIRO works.




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