Space Matter: Where We Came From

Space Matter(s) is a weekly column that delves into space science and the mechanics of spaceflight. From the latest discoveries in the universe around us to the fits and starts of rocket test flights, you’ll find analysis, discussion, and an eternal optimism about space and launching ourselves into the cosmos.

Sometimes it’s easy to forget that NASA is a large organization, with goals beyond human spaceflight. There are smaller and less-splashy programs within NASA doing incredibly important work in furthering our understanding of the world and universe around us. One such program is NASA’s Discovery, which began in 1992, that accepts submissions from teams of scientists and engineers to figure out where it should send robotic spacecraft. It was a real and pivotal shift in how NASA approached missions, and it’s had incredible effects.

These missions don’t replace the larger, more headline-grabbing (and more expensive) robotic spacecraft missions NASA does; they’re complementary. The idea is that the Discovery missions are lower cost, quicker to launch, and often utilize breakthroughs in technology to achieve their goals. It’s a ingenious program that has had great results—it gets the scientific, engineering, and educational public more invested in NASA, helps NASA do more with the resources it has, and furthers science.

Some Discovery programs you’ve likely heard of? Mars Pathfinder, the rover launched in 1996 and was celebrated by The Martian, as Mark Watney used the lander to communicate with Earth. Kepler, a personal favorite, the planet-hunting spacecraft that has discovered exoplanets large and small, and is still chugging along, three years after its primary mission concluded. These may not be the fanciest of missions, but they have helped us make advances in science and occasionally, even captured the imagination and attention of the public at large, no small feat.

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Last week, NASA announced the selection of two new Discovery missions, out of an incredible roster of candidates. Let’s take a more in-depth look at what was chosen, why, and what they could tell us about the universe we live in.

The first mission, Lucy, is headed for the asteroid belt. The current schedule is to launch in October of 2021, and to arrive in 2025. The mission will last until 2033, during which Lucy will explore six Jupiter Trojan asteroids. The Trojan asteroids are a cluster of asteroids, each with unique features, that orbit two Lagrangian points. A Lagrange point is an area between two larger bodies (in this case, Jupiter and the Sun) where a third body (in this case, the Trojan asteroids) can maintain a stable position due to the forces of gravity—think of it as a parking spot in space. There are five total Lagrangian points within the solar system.

Three Lagrangian points—L1, L2, and L3—are unstable. This means that any shift in direction would result in objects at that Lagrangian point falling towards one of the two bodies affecting it. For example, the James Webb telescope (Hubble’s replacement) is scheduled to be launched to the L2 Lagrangian point in 2018. If it were nudged out of place, it would fall either towards the sun or Earth, without being able to regain its former stability. Lagrangian points L4 and L5, however, are stable (and therefore, attractive possible locations for future space stations/space colonies)—a nudge towards the sun, say, would be offset by a pull from Jupiter, and it would be able to rebalance. That’s where Lucy is heading.

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Photo: Courtesy of NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

We’re interested in the Trojans because they may contain a peek at our history; consensus is that they were formed in the early days of the solar system, and they’re likely remnants of the primordial matter that made the outer planets. We get to literally take a look at the stuff we’re made of, exploring asteroids named after heroes of the Trojan War (the L4 Trojans are named after the Greeks, while the L5 Trojans are named after the Trojans), through a spacecraft named after our most famous early human ancestor. Space can be pretty poetic.

Photo courtesy of NASA/JHUAPL

Interestingly, the second mission, Psyche, is also headed for the asteroid belt (signaling NASA’s increasing interest in this area, perhaps?) to explore an asteroid called 16 Psyche, a giant asteroid stretching over 200 kilometers in diameter. It may not be the most interesting name, but the object itself is fascinating: it’s a full metal asteroid. From our observations, it appears as though 16 Psyche has no ice or rocky bits: it’s composed of iron and nickel, which also happens to be what our own solid core is made of.

That brings up interesting implications: is it possible that 16 Psyche was once the core of an ancient planet, one that was stripped of its outer layers by some sort of violent and epic space trauma? Not only does 16 Psyche present an opportunity to learn more about the history of our solar system and how it was formed, but we can also learn more about the Earth and what our own planet is made of. We’re heading to a space object to learn more about ourselves and our core in a craft called Psyche—pretty great, right? Psyche is targeted for a launch date of October 2023, with a Mars flyby in 2025, and arriving at 16 Psyche in 2030.

These missions are so important because not only do they help us understand ourselves and where we belong in the cosmos, but they also have practical real-world applications. NASA’s put a priority on studying asteroids—yes, they function as a sort of time capsule to the early solar system, but it’s also wise to remember that there are a lot of asteroids surrounding us. Literally—the asteroid belt lies between Mars and Jupiter. To navigate around these, to explore the depths of our own solar system, to help us prepare to deflect any Earth asteroid collisions, and even to mine the extensive natural resources present in the belt, we need to understand and study our neighbors.

Godspeed, Lucy and Psyche!

Top photo courtesy of NASA

Swapna Krishna is a freelance writer, editor, and giant space/sci-fi geek.