NASA needs a camera to detect murderous asteroids – Quartz


Astronomers tend to be patient people. When it comes to stars, much of what they examine happened millions of years ago, and when it comes to space probes, even the pre-launch preparation can take a decade or more.

But they are getting impatient with the launch of an infrared space telescope called NEOCam. It has a very specific mission: to identify objects near Earth – astronomical bodies, most commonly asteroids, whose orbits around the Sun could pass close to Earth and potentially collide with our planet, some of which could damage or destroy civilization itself.

It is not speculative; A major meteor impact is inevitable and we need to keep a better eye on the solar system.

"The question is: when will the next one happen on a human time scale, as well as a geological time scale?" Says Amy Mainzer, a scientist at CalTech Jet Propulsion Laboratory and principal investigator for the NEOCam project.

It's not that the US government is not interested. NASA has cataloged all near-asteroid-shaped asteroids around the globe, and Congress passed a law in 2005 requiring NASA to find 90% of objects near Earth 140 meters in diameter. .

One of the largest well-documented asteroid explosions in 1908 over Tunguska in Russia destroyed 2,000 square kilometers of forest. Scientists believe it is 40 to 60 meters in diameter.

The space agency has been given a deadline of 2020 to find these objects close to Earth. Will not make it. In June 2018, NASA's planetary defense official Lindley Smith said about 8,000 objects were detected, but scientists hope double will not yet be discovered. As an illustration of urgency, Smith then said that if one of these unknown objects is a danger to Earth, sending a spacecraft to intercept it would require a 10-year warning.

There is no plan yet to fulfill the mandate of Congress. NASA says it is waiting for a panel at the National Science Foundation (NSF) to complete a study of the best methods for finding near-Earth objects expected this spring before making its decision on NEOCam.

"I do not lose sleep at the risk of an undiscovered asteroid impacting the Earth because the odds are small, but they are not zero," says Richard Binzel, MIT planetary scientist who is not part of the NEOCam team but has defended his need for the NSF panel. "We have the ability, the responsibility of the adult, to simply know what's out there. And NEOCam is basically ready to go.

Another space probe called IMAP will be launched in 2024 to study the solar wind, heading to an orbit that is also ideal for NEOCam. There is space on your rocket for yet another payload, and asteroids say this is the best opportunity to launch the NEOCam, which Maizer first proposed in 2005 and spent 14 years refining. But they will need approval and funding soon to build the telescope on time.

Another important source of near-Earth object data will be the Large Synoptic Survey Telescope, or LSST. Funded by NSF, he will install a mirror the size of a tennis court on a mountain in Chile. In 2023, the telescope will begin a 10-year survey repeatedly capturing large-scale images of the night sky. Asteroid researchers hope to collect enough data to find about 75% of NEO objects 140 meters in diameter or more.

However, to achieve the 90% goal, space-based infrared observations will be needed – such as those that NEOCam is designed to collect. Infrared observations can do something that a terrestrial telescope can not: estimate the size of an asteroid. At visual wavelengths, astronomers have difficulty distinguishing between large and dark, small, bright objects, but infrared data can be used to solve this problem. This will be especially important when the LSST starts its work.

"I do not think anyone appreciates how shaken the initial part of the [LSST Survey] will be, when we start to see everything that is out there, "says Binzel. "A 10-meter object passes within the orbit of the Moon every week – and we will begin to see years and years of these" received "objects well in advance of their approach. attention to the larger objects of this input stream – and we need IR [infrared] characterization to solve this.

A wrinkle in the NEOCam plan is the work of Nathan Myhrvold, a physicist and former Microsoft executive. He has published research arguing that NASA data on near-Earth objects are more uncertain than their collectors think, in part because the source of these data, a space telescope called NEOWISE, was not originally designed to locate objects so close to our planet.

Mainzer, who is also NEOWISE's principal investigator, says that Myhrvold's analysis is flawed and that asteroid data have been confirmed against independent data and models from other independent researchers. E NEOCam is optimized for identifying near-Earth objects with specialized imaging chips that have been refined to capture high-resolution infrared images at a temperature of 40 ° K which is toasted compared to WISE chips operating at 8 °. K. This will allow NEOCam to collect data for a much longer period.

In addition to import into civilization, collecting asteroid data could serve other purposes for NASA. Cataloging asteroids could give the agency – and its growing set of trading partners – targets for future space missions, and public opinion polls suggest that Americans would prefer NASA to spend more time worrying about asteroid impacts than, for example, sending people to Mars.


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