NASA has made it its goal to find the location of 90 percent of large near-Earth objects (NEOs), including possible asteroids on a collision course with our planet, but the process is slow-going and expected to end way past its original 2020 deadline.
On Dec. 19, NASA authorities talked about the need for what has been dubbed the Near Earth Object Camera (NEOCam), their proposed space-based telescope, during the meeting of a National Academies of Sciences, Engineering, and Medicine committee on NEO observations, according to Physics Today.
But even with the NEOCam, NASA won't be able to make the deadline established in the 2005 NASA authorization act, which stipulated that the space agency would find the location of 90 percent of near-Earth objects such as asteroids that are 140 meters or larger in size. The projected date for this has been tentatively moved to 2034, but NASA could take even later in accomplishing this.
If NASA were to use only ground-based telescopes, NASA chief scientist Jim Green told the committee that it would take 30 years or more to be able to locate 90 percent of the near-Earth objects, basing on the current rate of discovery. Only around 500 large objects are being detected annually. Of the 25,000 NEOs larger than 140 meters believed to exist, NASA and its affiliated agencies have detected only one-third of this number over the last 20 years.
The yearly rate could increase when the wide-field Large Synoptic Survey Telescope in Chile comes on line around 2023, but this won't be able to contribute in the detection enough to fulfill the 90 percent requirement by the early 2030s.
As of late, NASA has sought advice from the committee regarding techniques that could be used to determine the sizes of asteroids. Green also asked them to evaluate pluses and minuses of IR and visible-light observations of asteroids.
UCLA astronomer and principal investigator on NASA's Wide-Field Infrared Survey Explorer (WISE) Edward Wright recommended the IR for asteroid-detection as most of these objects are apparently too dark to be observed in the visible spectrum. The WISE spacecraft had already fulfilled its original mission and was reactivated in 2013 as NEOWISE in order to prove that IR could be used to detect near-Earth objects. NASA's planetary defense officer Lindley Johnson, however, said that this spacecraft won't last another six months.
Led by NEOWISE principal investigator Amy Mainzer, the NEOCam spacecraft is currently about to enter the preliminary design phase. The estimated time it would take to finish designing, building and launching the probe is four years. However, the problem is that there may be no funds available to go through with this project.
With only $150 million in its planetary defense budget for 2019, NASA won't be able to fund both the NEOCam and the Double Asteroid Redirection Test (DART) mission, which also requires $150 million.
The DART mission is a planetary protection demonstration that is due for launch in 2020. It will show the effectiveness of one of three methods for deflecting asteroids on a collision course with Earth.
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