NASA’s Lucy spacecraft will add another asteroid encounter to its 4-billion-mile journey. On November 1, 2023, Lucy will get a close-up look at a small main-belt asteroid to conduct an engineering test of the spacecraft’s innovative asteroid-tracking navigation system.
The Lucy mission is already breaking records with plans to visit nine asteroids during its 12-year tour of Jupiter’s Trojan asteroids, which orbit the Sun at the same distance as Jupiter. It was originally planned that Lucy would not be able to see the asteroids up close until 2025, when it will fly by the main belt asteroid (52246) Donaldjohnson. However, the Lucy team identified a small, as-yet-unnamed asteroid in the inner main belt, designated (152830) 1999 VD57, as a potential new and useful target for the Lucy spacecraft.
“There are millions of asteroids in the main asteroid belt,” said Lucie collaborator Raphael Marshall of the Nice Observatory in France, who identified asteroid 1999 VD57 as an object of particular interest to Lucie. “I selected 500,000 asteroids with well-defined orbits to see if Lucy could travel close enough to get a good look at any of them, even from a distance. This asteroid really stood out. Lucy’s trajectory, as originally designed, would bring her within 40,000 miles of the asteroid, at least three times closer than the next closest asteroid.”
Lucy’s team realized that by adding a small maneuver, the spacecraft could get an even closer look at this asteroid. So, on January 24, the team officially added it to Lucy’s tour as an engineering test of the spacecraft’s pioneering terminal tracking system. This new system solves a long-standing problem for flyby missions: when a spacecraft approaches an asteroid, it is difficult to accurately determine how far the spacecraft is from the asteroid and in which direction to point the cameras.
“In the past, most flybys accounted for this uncertainty by taking many images of the region where the asteroid might have been, which means low efficiency and a lot of images of empty space,” said Hal Levison, Lucy’s Southwest Region Principal Investigator. Boulder Research Institute, Colorado Office. “Lucy will be the first flyby mission to use this innovative and sophisticated system to automatically track an asteroid during an encounter. This new system will allow the team to take many more images of the target.”
The 1999 VD57 proved to be an excellent opportunity to validate this procedure, which had never been flown before. The geometry of this encounter, particularly the angle at which the spacecraft is approaching the asteroid relative to the Sun, is very similar to the mission’s planned encounters with the Trojan asteroids. This allows the team to conduct a dress rehearsal in similar conditions long before the spacecraft’s main scientific goals.
This asteroid was not previously identified as a target because it is extremely small. In fact, 1999 VD57, estimated at 0.4 miles (700 m), would be the smallest main-belt asteroid ever visited by a spacecraft. It is much more similar in size to the near-Earth asteroids visited by NASA’s recent OSIRIS-REx and DART missions than to previously visited main belt asteroids.
The Lucy team will conduct a series of maneuvers starting in early May 2023 to place the spacecraft on a trajectory that will pass within about 280 miles (450 km) of the small asteroid.
Principal Investigator Lucy works out of the Southwest Research Institute in Boulder, Colorado, with headquarters in San Antonio, Texas. NASA’s Goddard Space Flight Center in Greenbelt, Maryland provides overall mission management, systems development, and mission safety and assurance. Lockheed Martin Space in Littleton, Colorado built the spacecraft. Lucy is the 13th mission in NASA’s discovery program. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the discovery program for the Science Mission Directorate at NASA Headquarters in Washington.
