Two of NASA's space telescopes — James Webb and Hubble — have captured views of the DART spacecraft intentionally smashing into an asteroid in a mission that is trialling technology for protecting Earth from potential asteroid collisions.
On Tuesday, DART intentionally crashed into asteroid Dimorphos some 9.6 million kilometres away from Earth, ploughing into the rock at 22,500 kilometres per hour.
It's the first time the Hubble Space Telescope and the James Webb Space Telescope simultaneously observed the same celestial target.
Hubble images show asteroid brightening after impact
Hubble captured images taken 22 minutes, five hours and 8.2 hours after the impact, photos from its wide field camera 3 show the impact in visible light.
Ejecta — which is material forced out from the impact — can be seen as rays stretch out from the asteroid's body.
NASA says the images show a slight curve in some of the rays, where astronomers will need to take a closer look to see what this could mean.
The bolder, fanned-out spike of ejecta to the left of the asteroid is in the general direction from which DART approached.
NASA astronomers estimate that, in the Hubble images, the brightness of the system increased by three times after impact and held steady even eight hours after DART had struck Dimorphos.
The brightening shows the evolution of ejected debris.
Johns Hopkins University applied physics laboratory's Andy Rivkin, the DART investigation team lead, has described it as an "unprecedented view of an unprecedented event".
View from James Webb telescope
NASA says images from James Webb's near-infrared camera show a tight, compact core with "plumes of material appearing as wisps streaming away" from where the impact took place.
In the weeks leading up to the impact, as DART approached its target, NASA says, its team performed additional work to enable and test a method of tracking asteroids moving more than three times faster than the original speed limit set for James Webb.
“I have nothing but tremendous admiration for the Webb Mission Operations folks that made this a reality,” Northern Arizona University's Cristina Thomas, a principal investigator, said. “We have been planning these observations for years, then in detail for weeks, and I’m tremendously happy this has come to fruition.”
Two telescopes working together to track asteroid
Observations from James Webb and Hubble, together, will allow scientists to gain knowledge about several key questions, including:
- the nature of the surface of Dimorphos
- how much material was ejected by the collision
- how fast it was ejected.
The two telescopes captured the impact in different wavelengths of light: James Webb in infrared and Hubble in visible light.
NASA says by using a wide array of wavelengths, it will help to determine whether the impact threw off lots of big chunks or mostly fine dust.
Understanding the distribution of particle sizes will help to understand how effectively an impact such as DART can modify the orbit of an asteroid.
Scientists will continue to observe Dimorphos over the coming weeks and months to determine how the mission impacted the asteroid's orbit.
What else have telescopes been doing?
Just last week, the James Webb telescope captured the clearest view of Neptune's rings in decades.
Not only has it taken the clearest view of this distant planet's rings in more than 30 years, but its cameras have revealed the ice giant in a whole new light.
Most striking in its new image is the crisp view of the planet's rings, some of which have not been detected since NASA's Voyager 2 became the first spacecraft to observe Neptune during its fly-by in 1989.
The James Webb image also clearly shows Neptune's fainter dust bands.
