NASA’s NEOWISE Watching Our Backs For Asteroids
Looks like we are in the clear for now…
NASA’s NEOWISE survey provides best estimate yet of potentially hazardous asteroids
To make predictions about the entire population as a whole, NEOWISE snapped images of about 600 NEAs and sampled 107 PHAs, allowing the project team to extrapolate that there are around 4,700 PHAs – give or take 1,500 – with diameters larger than 330 ft (100 m). It is estimated that around 20 to 30 percent of these PHAs have been found. NASA points out that previous estimates on PHA numbers reached similar conclusions, but NEOWISE’s observations provide a more credible estimate of their number and size.
Analysis of NEOWISE’s new observations also suggests that around twice as many PHAs are likely to reside in “lower-inclination” orbits, which are more aligned with Earth’s orbit, than previously thought. As these asteroids are more likely to encounter Earth and would be much easier to reach, they could become potential targets for future robotic or human missions.
“NASA’s NEOWISE project, which wasn’t originally planned as part of WISE, has turned out to be a huge bonus,” said Amy Mainzer, NEOWISE principal investigator, at NASA’s Jet Propulsion Laboratory. “Everything we can learn about these objects helps us understand their origins and fate. Our team was surprised to find the overabundance of low-inclination PHAs. Because they will tend to make more close approaches to Earth, these targets can provide the best opportunities for the next generation of human and robotic exploration.”
Read more here