What Are Asteroids Made Of?
What Are Asteroids Made Of?
Asteroids are space rocks. They come in different sizes, from small boulders to football field-sized ones. Some are even close in size to planets, leading to debates among astronomers about whether to call them planets.
Asteroids are composed of rock, metals, and various elements. Some may even have water. Depending on their composition, some asteroids can be loose piles of rubble, while others are solid like rocks.
Meteorites found on Earth often originate from asteroids, helping astronomers learn more about them. For example, iron meteorites can be mostly iron with some nickel and cobalt, while stony meteorites contain oxygen, silicon, magnesium, calcium, and other elements.
How Do Astronomers Know What Asteroids Are Made Of?
How can we learn about asteroid composition when we've only started visiting them recently? Alan Fitzsimmons explains that we can also study the asteroids that come to us.
Asteroids can provide insights into the Solar System's beginnings and possibly the origin of life. However, they also pose a threat to Earth as some come close to our planet regularly. Discover more about how ESA is safeguarding us through its Planetary Defence Office, part of the Space Safety program.
Has Anyone Managed To Take A Sample From An Asteroid?
A NASA-led team in Utah's West Desert is getting ready for the first U.S. asteroid sample's arrival, scheduled for September.
They recently performed a vital test by dropping a mockup of NASA's OSIRIS-REx sample capsule from an aircraft. It landed at the Utah Test and Training Range outside Salt Lake City, marking a crucial step before the actual capsule arrives on September 24. This capsule carries a sample collected from asteroid Bennu almost three years ago in space.
Nicola Fox, associate administrator of NASA's Science Mission Directorate, stated, "We are just weeks away from receiving a piece of solar system history on Earth, and this successful drop test ensures we're prepared. Pristine material from asteroid Bennu will help us learn about the formation of our solar system 4.5 billion years ago, and maybe even the origins of life on Earth."
How Does Spacecraft Take Samples From An Asteroid?
Asteroids are attractive for sample collection because of their weak gravitational pull, which allows spacecraft to approach and depart from their surfaces without using powerful rocket engines. This process is more like docking with a space station than landing on a planet.
To collect samples, spacecraft use the asteroid's weak gravity. They have extended collection funnels that touch the asteroid's surface and a way to dislodge material from beneath the funnel. Small rocks move up into the funnel and are directed into collection pods.
For example, Hayabusa2 collected samples from asteroid Ryugu by firing a small projectile into its surface to dislodge material. Surprisingly, they found that Ryugu's surface was gravel-sized rather than powdery as expected. To ensure a successful collection, they tested the system on Earth with centimeter-sized gravel.
Hayabusa2 used a reflective 'beanbag' to guide itself to the precise touch-down spot, performed a second sample collection from a crater it created, and is now on its way home.
On the other hand, OSIRIS-REx uses a touch-and-go (TAG) maneuver for sample collection. It maps its target area and guides itself to the surface using Natural Feature Tracking. Instead of a solid projectile, it stirs up Bennu's regolith by discharging nitrogen gas canisters when the funnel touches down, and the contact lasts for about five seconds.
OSIRIS-REx's first sample collection attempt is scheduled for October 20. Pictures will be taken of the collection head two days later to check if samples were captured, and a spin maneuver will be performed to determine the sample's mass. OSIRIS-REx plans up to three sample collections and will return them to Earth on September 24, 2023, while Hayabusa2's samples will arrive on December 6 of the same year.
