NASA Just Announced Two New Missions, But Shelved Others

Though the new missions have exciting prospects, some scientists aren’t thrilled by the decision

NASA's New Discovery Missions

This week, NASA announced two new missions set to explore asteroids in our solar system. During the 2020s, the space agency will launch two separate spacecraft to study a pair of asteroids. But while these missions could unveil new details about the origins of our cosmic neighborhood, the decision means that future missions to planets like Venus have been put on the backburner.

In order to decide what missions to take up next, NASA put out a call for scientists to submit proposals to the Discovery Program. The program has spawned all sorts of missions exploring our solar system, including the Lunar Prospector, Kepler space telescope and the future Mars InSight lander. Now, NASA has announced its two latest winners: a pair of missions set to study two very different kinds of asteroids.

“These are true missions of discovery that integrate into NASA’s larger strategy of investigating how the solar system formed and evolved,” Jim Green, director of NASA’s Planetary Science division, says in a statement. “We’ve explored terrestrial planets, gas giants, and a range of other bodies orbiting the sun. Lucy will observe primitive remnants from farther out in the solar system, while Psyche will directly observe the interior of a planetary body.”

While both missions are focused on asteroids, Lucy and Psyche are worlds apart. The Lucy mission is set to study multiple members of the Trojan asteroids—a swarm that orbits the gas giant Jupiter—in an effort to learn more about the materials that the outer planets are made from. Psyche, on the other hand, will travel to a 130-mile-wide asteroid that is almost entirely made of metal: a rarity that astronomers believe was once the core of a long-gone planet, Loren Grush reports for The Verge.

Though these missions are intriguing, the decision to focus so much on asteroids is raising eyebrows among some scientists. Of the five finalists for this round of the Discovery Program, three were asteroid missions and two focused on the planet Venus. Some, however, thought NASA should be more interested in exploring the next planet over, Sarah Fecht reports for Popular Science

NASA also currently has two asteroid-focused missions in progress: the Dawn mission surrounding Ceres and the OSIRIS-REx mission en route to the asteroid Bennu, Sarah Kaplan reports for The Washington Post. And the decision means it will be some time before Venus gets its time to shine.

"I thought for sure they'd pick a Venus mission. I found it pretty surprising," planetary scientist Mark Marley tells Fecht. "If we're trying to understand atmospheres on exoplanets, we really need to understand as much as we can about our own Venus. It's very hard to get exoplanet data, and it's always lower quality than what you can get in the solar system."

Unlike Mars and the airless asteroids, Venus has a thick, protective atmosphere. As Kaplan reports, that makes the third planet from the sun a great candidate to learn more about how atmosphere works and how it could shelter organic molecules. The last time NASA sent an orbiter to Venus was in the 1970s. 

That doesn’t mean all hope is lost for those hoping to send a new spacecraft to visit Venus. NASA will be picking a new mission for its New Frontiers program in 2017, and officials have said that exploring Venus and Saturn are two of its top priorities for the bigger-budgeted division, Fecht reports. In the meantime, Lucy and Psyche are sure to reveal fascinating new information about the earliest days of our solar system.

Get the latest stories in your inbox every weekday.