by Comet C/2022 E3 (ZTF) is tempting to spot through a telescope, but what would it look like up close?
Scientists have no way to get a spacecraft into the stunning green comet as it swings through the interior solar system – but the next decade they will, thanks to the comet interceptor of the European Space Agency (ESA). This mission, scheduled for launch in 2029, will spend a few years perched nearly 1 million miles (1.5 million kilometers) from Earth, waiting for an intriguing comet to venture deep enough into the inner solar system to fly overhead. But if Comet Interceptor was already in space, scientists might have sent it to Comet C/2022 E3 (ZTF).
“Comet ZTF, the brightest comet currently in the sky, is in fact the most promising virtual target for Comet Interceptor so far,” said ESA Comet Interceptor study scientist Michael Kueppers. during a NASA Small Body Evaluation Group meeting on Wednesday (Jan. 26).
Related: Stunning photos of the beautifully green comet C/2022 E3 (ZTF)
Kueppers said the science team was preparing for the mission by evaluating “virtual targets” – objects the Comet Interceptor team might consider visiting if the probe was already in space. Whichever comet ends up hitting the odds will be given a thorough, albeit brief, inspection by the main spacecraft and two smaller probes.
Mission scientists hope to target an active comet that has never passed by. Sun before. Such an object would come from ice Oort cloud far beyond the orbit of Pluto; by catching an object on its first loop of the sun, scientists could see pristine material respond to the sun’s heat.
Or, if Comet Interceptor is particularly lucky, scientists will spot another interstellar object, a successor to ‘Oumuamua and Comet Borissov which makes a unique jaunt through our solar system.
It’s an unusual situation for a mission – although many spacecraft gain additional targets after launch, Comet Interceptor will be in space before scientists see its primary target.
The spacecraft will hitch a ride with ESA’s Atmospheric Remote-sensing Infrared Exoplanet Large-survey (Ariel) mission, which will spend four years analyzing the atmospheres of as many as 1,000 exoplanets.
After launch, Comet Interceptor will head towards Earth-Sun Lagrange point 2 (L2), the same deep “parking spot” as James Webb Space Telescope orbits. At Lagrange points, the gravitational tugs balance each other out, so it will be relatively cheap to keep the spacecraft at its station while scientists identify a promising target. The team will have to decide on their plans at least six months before leaving L2 for a date with a comet.
But imagine that Comet Interceptor was already at its station in early March 2022, when scientists first spotted Comet C/2022 E3 (ZTF). Puzzled mission personnel might have started toying with the trajectories that Comet Interceptor might use to encounter the object. They would find that, if the spacecraft had departed in late August, it could fly past the comet on February 12, just a month after the snowball’s closest approach to the sun and just under a year after the discovery. of the object.
But C/2022 E3 is not an ideal target, Kueppers noted. The team would have to get ready for departure fairly quickly, and the flyby would happen a bit farther from the sun than the scientists would like. And while mission personnel hope to catch a comet that has never visited the inner solar system before, C/2022 E3 did, but about 50,000 years ago.
“It’s probably not dynamically new,” Kueppers said. “He’s reasonably active so we can take him, but it depends on the activity.”
And if this scenario happened during the real Comet Interceptor mission, the preparation time for departure would probably not be an issue. It is thanks to the Vera Rubin Observatory in Chile, which will conduct a 10-year Survey of Space and Time (LSST) beginning in early 2025. The LSST is expected to uncover some 6 million solar system objects, and much of what it will find will arrive relatively early in this investigation.
“The discovery is a bit late, but that doesn’t worry us because we expect these comets to be discovered much sooner with LSST,” Kueppers said of the C/2022 E3 virtual scenario.
The analysis highlights the kinds of decisions scientists will have to make during the Comet Interceptor mission. They’ll only get one shot, and they don’t know in advance what the solar system will throw at them. If they are too impatient, they may miss a more intriguing target. if they’re too careful, they can still find themselves in L2 years after launch, running out of time with no target in sight. While the dream is a long-period active comet, the team will have to see what happens and if an object like C/2022 E3 would snag a visit.
“Statistically, we expect that we have a few candidate targets, not dozens,” Kueppers said. “We also can’t rely on a dynamic new comet, so we would potentially use a comet like ZTF.”
Email Meghan Bartels at mbartels@space.com or follow her on Twitter @meghanbartels. follow us on Twitter @Espacedotcom and on Facebook.
