NASA asteroid missions can save Earth AND publish its history
Asteroids are like the remnants of the early solar system, capable of revealing mysteries about the origin of our planet. But they could also end life on Earth. Now two missions, Lucy and DART (Double Asteroid Orienteering Test) will provide further insight into these two features - with DART even attempting to redirect a lunar orbit around an asteroid.
Space rocks are generally considered as asteroids if they are larger than about 1km in size and made of “non-volatile” materials - chemicals that can be easily moved. Carbon monoxide, for example, is volatile because it decomposes at a temperature of -191 ° C. However, iron, with a vaporization point of 2,862 ° C is volatile.
This is a little different from comets. Asteroids are more commonly found in the Inner Solar System, and comets with them volatile-rich shape tends to hide in the outer part, far from the heat of the sun. About 500,000 asteroids have been cataloged so far, and many have their own small asteroids.
Asteroids are thought to be the remnants of planets - the precursors of the planets in the early solar system, which came together deep to form the worlds we know today. Asteroids somehow escaped this process, preserving some of the conditions of our Solar System, from a time before even the planets were created. This moment is very secretive. The fact that tiny dust particles, which were like most hard materials at the time, can still collect and form larger objects such as asteroids, as they did not have their own gravitational fields, is still being studied.
The most famous of the asteroids are those that live in the main belt, a strong swarm of millions orbiting the sun between Mars and Jupiter. This sounds like a lot, but it's a big place and the distances between one asteroid and a neighbor are usually millions of kilometers. So the chances of successfully navigating an asteroid range, at least in our Solar System, are far better than 3,720 to 1.
The US $ 980 million (£ 714 million) Lucy spacecraft - launched on October 16 - will fly through three asteroid missions over its 12-year mission. It is named Lucy after the famous fossil of hominin, as it is hoped that it could be similarly revolutionary for our knowledge of the origin of the Solar System. Lucy first flies through the main belt, then travels out to visit two other lesser known asteroid fields - the Jupiter Trojans.
Trojan asteroids orbit the sun at the "lagrange points". These are positions in space where the gravitational pull of the sun and planet balances out so that an object naturally located there remains in its place, perhaps for billions of years. There are five such points for all planets in the solar system and they are numbered L1-L5 (see picture below). The Jupiter Trojans, clustered at L4 and L5, are two very large and unexplored asteroid ranges, which between them harbor at least as many asteroids as the main belt.
Lucy first goes to the L4 Jupiter Trojans, which she arrives in 2027. She then flies back to Earth, using the gravity of our planet to throw her back out to L5 Jupiter Trojans, which arrives in 2033. This amazing flight the journey will be accomplished by solar-electric movement.
The spacecraft carries a series of instruments including solemn cameras and spectrometers to map the asteroids and identify their writing. The chemical composition of the Jupiter Trojans is expected to be slightly different from the main belt asteroids, which have a higher density of volatile matter, obscuring the distinction between asteroids and comets. In fact, one Jupiter Trojan was recently discovered to have a comet-like tail.
Not all asteroids are belted. Some walk around the solar system on orbits that take them close to planets like Earth. The danger of the impact of asteroids has been largely revealed, especially after the Chelyabinsk meteor exploded over a Russian city in 2013, injuring more than 1,000 people and causing massive damage.
Sometime in late November, NASA will attempt to launch DART. This spacecraft will attempt to stop 65803 Didymos, an asteroid near Earth with its own small moon, called Dimorphos. The moon will be about 170 meters in size hit by the 500kg DART spacecraft with an impact speed of 6.6 kilometers per second. The goal is to observe a change in Dimmorphos' orbital motion around Didymos as a result of the crash.
This will be accomplished by a follow-up mission launched by ESA, called Hera, which will reach Didymos in 2026 and closely study the orbit of Dimorphos. By measuring the change in the orbit of the small moon, scientists and engineers will be able to better work out how much energy is needed to change a future asteroid orbit. It must be emphasized, for now, that future asteroid-Earth crashes are not known, but clearly it is better to prepare for such an event.
There are even more asteroid missions coming soon. In August 2022, NASA will launch Psyche to visit the asteroid named 16 Psyche, which will orbit in the main belt. This particular world is over 200km across and contains a lot of metal. So much so that it is believed that it was the open heart of a once growing planet in the early Solar System, which at some point in the past suffered a devastating impact.
This crash destroyed the outer layers of the new planet, leaving the open heart full of metal behind it. If this theory turns out to be correct, this is the first time that scientists will have the opportunity to take a direct look at the heart of a planet.
This number of upcoming missions, and many of the recent ones, represent something of a golden age in asteroid research. Asteroids still have many stories to tell, have great economic potential as mineral resources, and are an obvious threat to civilization on Earth.
This article by Gareth Dorrian, Postdoctoral Researcher in Space Science, University of Birmingham is republished from The Conversation under a Creative Commons license. Read the original article.