Webb reached its planned orbit back in January but had to go through a six-month commissioning period to make sure all of its instruments were functioning properly. During this period, Webb homed in on “local” targets including Jupiter and several asteroids to test its tools. It’s this data that NASA is now releasing.
The image above shows Jupiter and its moon Europa (left) as seen through Webb’s NIRCam instrument with its 2.12 micron filter. The planet’s Great Red Spot is clearly visible, as are the distinctive bands that encircle the gas giant. “Combined with the deep field images released the other day, these images of Jupiter demonstrate the full grasp of what Webb can observe, from the faintest, most distant observable galaxies to planets in our own cosmic backyard that you can see with the naked eye from your actual backyard,” said Bryan Holler, a scientist at the Space Telescope Science Institute in Baltimore.
Webb was also able to spot some of the rings of Jupiter using the NIRCam’s 3.23 micron filter. “The Jupiter images in the narrow-band filters were designed to provide nice images of the entire disk of the planet, but the wealth of additional information about very faint objects (Metis, Thebe, the main ring, hazes) in those images with approximately one-minute exposures was absolutely a very pleasant surprise,” said John Stansberry, observatory scientist and NIRCam commissioning lead at the Space Telescope Science Institute.
The team was also pleased with Webb’s ability to track moving objects. The scope was designed to track objects that move as fast as Mars, which has a maximum speed of 30 milliarcseconds per second. In testing with various asteroids, the team found that Webb can get valuable data on a target moving at up to 67 milliarcseconds per second – more than twice as fast as it was designed for. “Everything worked brilliantly,” said Stefanie Milam, Webb’s deputy project scientist for planetary science based at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
