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NASA Unveils Two New Missions To Study Truly Strange Asteroids (space.com)
An anonymous reader quotes a report from Space.com: NASA's next low-cost planetary missions will attempt to unravel the mysteries of some seriously bizarre asteroids. The space agency has selected projects called Lucy and Psyche via its Discovery Program, which funds highly focused space missions to destinations throughout the solar system. The Lucy project will investigate the Trojan asteroids, which share an orbit with Jupiter, while Psyche will journey to the asteroid belt to study a huge, metallic asteroid named 16 Psyche that resides there. Lucy is scheduled to launch in October 2021. If all goes according to plan, the probe will visit an asteroid in the main asteroid belt -- located between Mars and Jupiter -- in 2025, and then go on to study six Trojan asteroids between 2027 and 2033, NASA officials said. There are two streams of Trojan asteroids. One trails Jupiter, and the other leads the giant planet around the sun. Scientists think both streams may be planetary building blocks that formed far from the sun before being captured into their current orbits by Jupiter's powerful gravity. Psyche will explore one of the oddest objects in the solar system -- a 130-mile-wide (210 kilometers) metallic asteroid that may be the core of an ancient, Mars-size planet. Violent collisions billions of years ago might have stripped away the layers of rock that once lay atop this metallic object, scientists say. Psyche is scheduled to launch in October 2023 and arrive at the asteroid in 2030, NASA officials said.
There is no shockwave. Instead, the energy remains predominantly X-rays. These penetrate into the surface and rapidly convert it to plasma, which sends a powerful burst of plasma, gas and debris in one direction and a powerful shockwave through the object, shattering it and imparting momentum to the fragments.
There's a common myth (sometimes even promoted by scientists who haven't worked on the issue of asteroid deflection) that using a nuclear warhead against an asteroid means that you'll just split it into pieces that are even more destructive than it was before. This is not in accordance with the actual peer-reviewed literature on the subject. There've been a number of projects to do supercomputer simulations, and the results of nuclear deflection - both through standoff "pushing" or direct high-intensity surface impact - are better than even hoped. With very reasonable sized nuclear weapons (compared to the size of the body) you can break asteroids into pieces that tend to be very small, moving at velocities well too fast for it to recoalesce. You can also very readily impart an impulse to significantly change the asteroid's trajectory, whether you destroy it or not.
And even if this wasn't the case, researchers in the field are far from in agreement that one large impactor is worse than multiple smaller impactors; smaller impactors aren't as good at excavating material, and the fact that they're spaced out in time reduces the peak heating for the most "survivable" areas. And of course pieces below a certain size suffer a great deal of ablation and/or decleration and excavate nothing. Larger pieces that airburst, while they flash a large area, usually airburst high enough that surface damage can be limited in the damage zone (see, for example, Chelyabinsk - was that really worse than detonating a 500kT bomb at the surface?), and likewise excavate little to no material.
For the love of Crom, am I the only one here who wants to keep the U.S. technologically competitive?
It is important to learn to walk before you attempt to run. In case you cannot wait, we'd be happy to strap your ass to rocket and send you to the nearest star. Please write often, we'd love to hear how it is going.
We already learned to walk... you're probably a millennial who was not there on July 20th, 1969 when we took our first steps. That almost 50 years ago this year. Guess what we were learning to do in 1919, 50 years before that? We had just completed the first non-stop transatlantic flight.
50 years before that, the biggest deal in 1869 was closing on the funding for the Beach Pneumatic railway... and it was 10 years before Edison demonstrated his electric light bulb in Menlo Park.
We are sitting around these days, mostly staring at our belly button lint. But we are proud of ourselves, for using robots to do it. It turns out it's the same belly button lint that was there in 1969.
We seem to be saddled with an overabundance of one of:
1. Caution
2. Roboticists, sucking the funding out of everything interesting
3. People with sticks up their asses
Pick one, but we should have a colony on the moon already, if not Mars (at least a Phobos base for the asteroid mining fleet).