Slashdot Mirror
NASA's InSight Successfully Lands on Mars (theverge.com)
NASA's latest Mars lander, InSight, successfully touched down on the surface of the Red Planet moments ago, surviving an intense plunge through the Martian atmosphere. From a report: It marks the eighth picture-perfect landing on Mars for NASA, adding to the space agency's impressive track record of putting spacecraft on the planet. And now, InSight's two-year mission has begun, one that entails listening for Marsquakes to learn about the world's interior. After six and a half months of traveling through space, InSight hit the top of Mars' atmosphere a little before 3PM ET. It then made a daring descent to the surface, performing a complex multi-step routine that slowed the lander from more than 12,000 miles per hour to just 5 miles per hour before it hit the ground. To get to the surface safely, InSight had to autonomously deploy a supersonic parachute, gather radar measurements, and ignite its thrusters all at the right time. Altogether, the landing took just under seven minutes to complete, prompting the nickname "seven minutes of terror." "InSight's view is a flat, smooth expanse called Elysium Planitia, but its workspace is below the surface, where it will study Mars' deep interior," Nasa posted Monday, sharing the first photo after the landing.
This probe didn't have sensors, but that data is pretty well known. The radiation environment in deep space was measured throughout the Apollo years through Pioneers 6/7/8 were placed into Solar orbit to measure the radiation environment.
Additionally, most of the deep space probes (Voyager 1/2, Pioneer 10/11, all had particle/plasma detectors on them to detect the radiation environment.
So yes, there's pretty darned good data on the radiation environment of deep space.
...si hoc legere nimium eruditionis habes...
Yes, because they occur on the Earth.
No, the word earthquake goes back to the 14th century, a century before the planet was first called Earth. It means ground, not the planet.
Which is rather obvious, because the entire Earth does not quake.
The CubeSats are not in Martian orbit - they didn't have engines to slow down or a heat shield to bleed off energy (only small attitude thrusters). They just flew by Mars, and will be in an elliptical orbit around the Sun.
Seriously... it really does. It rings like a bell as the P and S waves travel through and around the planet. This is actually the principle that allows InSight to work. The fact that a quake is detectable anywhere because it creates vibrations of the entire planet. The Sendai, Japan quake actually altered the axis of mass of the Earth by about 6.5 inches.
InSight will watch for P, S, and surface waves (a total of 5 types in all) and use that information to figure out the original position of the quake and how the waves change from their origin will give clues as to the internal structure of the planet. Just as on Earth, earthquake waves are refracted and reflected and speed up/slow down as they travel through different mediums. It is a brilliant bit of science they are about to start in on.
Well, Merriam-Webster has an entry for moonquake. Oxford lists marsquake. The Free Dictionary has sunquake. Dictionary.com lists starquake.
While the 14th century usage may have meant something else, it's certainly well known that the entire planet Earth does in fact quake during an earthquake. Why do you think remote sensors can detect earthquakes half way around the planet? Definitions of words change over a couple of years, let alone several centuries. In this case, I'd say the term "earthquake" as in the planet is more accurate than the original definition. But it becomes problematic when you're talking about a quake on another celestial body.
I also believe the "earth", as in dirt, that was referred to in the 14th century was generally referring to cultivable topsoil. You're not going to find much of that on the moon, mars, or a star.