This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: With a successful Mars gravity assist in its rearview mirror, NASA's Psyche spacecraft has fired up its thrusters and is accelerating toward the metal-rich asteroid of the same name. During the first leg of its journey, following an October 2023 launch, the mission used its electric propulsion system intermittently to maneuver into the right position to harness Mars' gravity for a propellant-saving speed boost and a slight trajectory change.
On Sept. 28, the spacecraft began to use its propulsion system nearly continuously, pausing just once each week to check in with mission controllers on Earth. This keeps the mission on track for its rendezvous with the asteroid Psyche in the main asteroid belt by the summer of 2029. "It's now 'pedal to the metal' to the asteroid Psyche," said Don Han, the Psyche mission's navigation lead at NASA's Jet Propulsion Laboratory in Southern California, which is managed for the agency by Caltech.
"We will be running our propulsion system at every available opportunity, pausing only for necessary engineering activities. The thrusters will be operating nearly 90% of the time from now until we reach the asteroid." Where conventional spacecraft thrusters rely on large quantities of fuel to provide powerful bursts of thrust for relatively short periods of time, the Psyche spacecraft's solar-powered propulsion system uses electromagnetic fields to steadily deliver up to 250 millinewtons of force—about the force you would feel from the weight of one AA battery in your hand. The highly efficient system relies on a mechanism known as the Hall effect, in which charged atoms, or ions, of the inert gas xenon are expelled to create thrust—and a bright blue glow.
The four thrusters operate one at a time. Though the thrust is tiny, its effect builds up over the course of the journey, enabling the spacecraft to gain speed as it travels through interplanetary space. At its maximum speed during cruise, the Psyche spacecraft will be traveling more than 100,000 mph (160,900 kph) relative to an observer on Earth.
The spacecraft uses its two five-panel, cross-shaped solar arrays—with a sunlight-collecting area of 800 square feet (75 square meters)—to generate electricity to charge its batteries and power its systems, including the propulsion system. The spacecraft launched with nearly 2,400 pounds (1,090 kilograms) of xenon in seven fuel tanks. In the three years since launch, it has used about one-third of that supply, leaving plenty to reach its target and assist the spacecraft as it orbits the asteroid Psyche during a two-year prime science mission.
"There are some unique things that mission designers need to consider with a propulsion system that is powered by the sun," said Steve Snyder, the Psyche mission's lead engineer for propulsion operations at JPL. "For the next three months, we'll be thrusting at full power before we begin slowly throttling down to approximately half power as the spacecraft moves farther away and its solar arrays receive less sunlight and generate less power." Discover the latest in science, tech, and space with over 100,000 subscribers who rely on Phys.org for daily insights. d research that matter—daily or weekly. Another consideration for mission designers: Despite how gentle the Hall-effect thrusters are, using them requires consistent management throughout cruise.
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