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
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.
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.