The solar system’s strangest objects are unlocking its history

Illustration of an engraved eye with a comet shooting across the center
Illustration: Natalie Peeples/Axios

A clutch of upcoming space missions will give scientists unprecedented views of some of the oddest objects in the solar system.

Why it matters: The solar system is still a largely mysterious place. Scientists aren’t sure exactly how planets came together billions of years ago or how life developed on Earth — and whether it took hold on other worlds.

  • The strange properties of odd objects could reveal something about our universe that isn’t available through more well-studied objects in the solar system.
  • “It doesn’t necessitate that we go to really weird, exotic places, but it could be that some of these exotic, weird places may be the linchpin in understanding a particular question,” says Paul Byrne, a planetary scientist at Washington University in St. Louis.

What’s happening: Next year, NASA is sending a robotic mission to Psyche, a largely metal asteroid that is thought to be the leftover core of a long-dead planet that formed early in the solar system’s history.

  • The agency’s Dragonfly spacecraft, launching in 2026, will explore Titan — one of Saturn’s moons with lakes of liquid methane and dunes of hydrocarbons — to search for signs of life and possibly learn more about where it comes from in the solar system.
  • Lucy, a NASA mission on its way to a group of asteroids near Jupiter’s orbit, will endeavor to learn more about those space rocks, which are thought to be extremely old and leftover from the dawn of the solar system.

Context: Learning more about the outliers of the solar system has already upended scientists’ understanding of how planets in our solar system function and evolve.

  • When NASA’s New Horizons flew by Pluto, it found a world rich in geology, something researchers didn’t think was possible so far from the Sun in an exceedingly cold part of space.
  • Pluto’s mountains and plains forced researchers to re-examine long-held ideas about how a planet cools and what worlds past Neptune may look like.
  • “We’re learning how planets work … just from visiting one outlying planet and being confused by what we find there,” NASA astronomer Henry Throop says.

The intrigue: Understanding outliers not only provides clues about the solar system, but it can also help scientists learn more about worlds and objects far from Earth.

  • “Our solar system is one example of one planetary system. And it’s also a snapshot in time of one system,” NASA scientist Megan Ansdell says. “So there’s a lot to learn in our solar system, but it’s also just one example.”

  • It’s possible the odd objects in our solar system are actually common in others, so learning more about them gives scientists access to what other star systems could look like.

For example, Arrokoth — an object studied by New Horizons after its encounter with Pluto — looked very different from what scientists expected, but could be representative of what other objects in its part of space look like.

  • What’s strange is that it may be roughly the same shape as ‘Oumuamua, the first confirmed interstellar object to pass through our solar system, Byrne said.
  • “Arrokoth is freaky looking,” Byrne said. “It just doesn’t look right because it’s had a completely different formational and impact history than anything that’s been closer to the Sun.”

The big picture: NASA and other agencies have limited funds to devote to various space missions so they need to pick destinations based on the scientific return they can get.

  • And strange objects — like Pluto, Titan, Psyche and others — could provide the highest bang for scientific buck.
  • “The whole point of looking at something weird is because that’s where we learn stuff,” Throop says.

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