Scientists are gathering more data, details and answers about asteroids than ever before.
Why it matters: Asteroids are thought to be key to unlocking exactly how planets and other bodies formed from a roiling mass of gas and dust orbiting the Sun billions of years ago.
- These relatively small bodies in the solar system represent the leftovers of planet formation — from pristine asteroids that haven't changed much in billions of years to others that may have once been parts of larger bodies.
State of play: Researchers have been studying asteroids for decades, but current missions will deliver to Earth some of the first direct samples from asteroids, allowing scientists to study them with high-powered instruments on the ground.
- NASA's OSIRIS-REx spacecraft gathered a sample of the asteroid Bennu last year with the plan to return it back to Earth in 2023.
- The mission is designed to help piece together how life may have formed early in our planet's history by searching for the chemical markers and resources — water, carbon, etc. — considered precursors to life.
- Another mission — Hayabusa2, from Japan — returned a sample of an asteroid back to Earth in December 2020. Some of that analysis began this summer.
What to watch: A new crop of missions is expected to further change how scientists understand these strange objects.
- NASA's Lucy spacecraft — set to launch in October — is designed to study a group of asteroids near Jupiter called the Trojans, which are thought to be the material left behind from the formation of the giant planets.
- "From an exploration point of view, we're going to see something we've never seen before," Hal Levison, the leader of the Lucy mission, told me.
- Another mission, expected to launch in August 2022, will study the asteroid Psyche, thought to be made predominantly of metal that could be from the destroyed core of a planet. That will help scientists figure out how planets like ours — which has an iron core — formed.
- "My secret dream is to look at Psyche and see something just visually bizarre," Lindy Elkins-Tanton, the principal investigator of the Psyche mission, told me, explaining that the metal-rich world may have odd-looking craters and boulders owing to its strange composition.
Between the lines: This kind of research into asteroids is about more than just basic science. Some asteroids cross Earth's path through space, putting our planet at risk for an impact.
- Science done by OSIRIS-REx, for example, has refined scientists' predictions about whether Bennu may ever impact Earth, with a recent study showing that the asteroid will make a relatively close pass of the planet in 2135 without posing a threat.
- NASA's DART mission is expected to meet up with an asteroid and help scientists learn how to deflect it if a space rock ever were to threaten Earth.
The big picture: Planets have been a major focus of scientific efforts, but they're just one indicator of how our solar system formed.
- "It turns out that there's as much or even more variety in the small bodies than there is in the big planets that we're familiar with, and the small bodies inhabit all the parts of the solar system," Elkins-Tanton said.