The Mars rover is on its way to Mars. In fact, it’s more than halfway. In 91 days, on February 18, 2021, it will begin its descent to the Red Planet, pushing the thin air there at hypersonic speed, slowing to where a parachute can be used to slow it further, then descending. from a rocket-powered sky crane to the surface.
Yes, seriously. Do you remember Seven Minutes of Terror? Literally the same thing here: Persistence will use the same sequence of entry, descent and landing (or EDL) that Curiosity uses.
One difference, however, is a specially installed microphone that will record the whole thing. He will hear the wind rushing in, the celestial crane firing, and perhaps even the dust and sand rustling when he touches down.
But on October 1
And what he heard was the buzzing heat pump buzzing.
Now I know: The sound itself is a little striking. But you need to understand what you are hearing. And why.
Martian winters are extremely cold. It’s not exactly Florida, even in summer, but it’s cold enough in winter to freeze carbon dioxide straight from the air. Many rover equipment will not work well in this type of cold and must be heated.
Fortunately, Perseverance carries a piece of plutonium with it.
Oh, you didn’t know this shoot was nuclear? Hmm. Solar panels work on Mars, but the rover has many moving parts that need more energy than solar energy can provide, so there is what is called radioisotope thermoelectric generator (or RTG)which uses the decay of plutonium to produce electricity. It is very efficient – it generates 110 watts of power – and lasts a long time. They have been used successfully in many missions in the outer solar system and have even been used by Apollo’s missions to the moon.
It also generates a significant amount of heat (worth 2,000 watts, about the same amount of heat that 20 people emit, only they are alive). So the rover has tubes running through it, filled with coolant (CFC-11 and Galden HT-170, if you should know – the chassis and some architecture of Perseverance is the same as for Curiosity). They take heat from the RTG and distribute it through the rover where needed. Moving this fluid takes pumps to move it and these pumps have parts that rotate quickly, creating a vortex, lifted from the microphone.
So that kind of crushing low, muffled buzz you heard? These are actually fast-rotating parts in a pump designed to move antifreeze through a one-ton stationary mobile chemistry lab that will look for signs of truly ancient life in a dried-up lake bed on another planet. While he was still in space on the road.
Now does this sound have a greater impact?
You may be wondering why we can hear anything at all, given that the rover is in a vacuum of space. Sound needs an environment through which to travel, some substance, and for us on the earth’s surface it is usually air. But sound can travel through water and even solidly, compressing and diluting the material it passes through. The pumps expel liquid and the constant vibrations are transmitted through the body of the rover into the microphone. here. The sound.
Oh, by the way, there’s a second Perseverance microphone designed to listen in SuperCam, an instrument located in the rover’s head that also has a powerful laser that will close the rocks, evaporating them and making them glow briefly. The spectroscope in the chamber will then divide this light into colors that will allow scientists to determine what is in the rocks and in what abundance.
So Perseverance is actually a monotonous mobile laboratory with nuclear-powered chemical laser eyes.
Finally, having said all this, did you know that it is possible for sound to move in space? You just need the space not to be completely empty. In nebulae – gas clouds – the gas is incredibly thin, mostly a laboratory vacuum, with perhaps only a few thousand atoms per cubic centimeter. But when you cross a few light years, it makes a a lot cubic centimeters, which adds a significant amount of gas. It is dense enough that very low frequency (or long waves, if you prefer) sound waves I can travel through them. They sometimes have visible effects, such as when a black hole has carved huge waves into the surrounding gas or even ripples made in the primary plasma filling the universe shortly after the Big Bang (try to omit the phrase baryonic acoustic oscillations in your next call).
Of course, these are quite violent events. I guess if you do it hard enough in space, everyone I hear you screaming.
Or, in case of perseverance, hum softly.