Dr. Nathan P. Myhrvold, formerly the chief technologist at software giant Microsoft, is putting quite a damper on things at NASA by critiquing their analysis of asteroids.
There are over 14,000 known asteroids streaking through Earth’s vicinity, all of which will miss the planet in the coming decades. But there are also hundreds of thousands that have not been discovered and no one knows if any of them will be hitting Earth soon. Finding and tracking asteroids that could cross Earth’s path is important so that something can be done to prevent it.
NEOWISE is a project under the Wide-field Infrared Survey Explorer (WISE) mission of NASA. NEOWISE gathers asteroid measurements and comets from WISE images and provides a database for searching WISE data for solar system objects. NEOWISE uses heat emissions data to calculate the size and reflectivity of 158,000 asteroids.
Myhrvold argues that the NEOWISE analysis has many flaws, according to the New York Times. “The bad news is it’s all basically wrong,” he says. “Unfortunately for a lot of it, it’s never going to be as accurate as they had hoped.” He isn’t saying that NASA has overlooked dangers from the asteroids they know of, but he thinks that scientists don’t know as much as they think they do.
The former Silicon Valley exec has also taken a stab at the Near-Earth Object Camera or Neocam, a space-based telescope that costs more than half a billion dollars that is being headed by some of the same scientists working on WISE and NEOWISE.
From the practical perspective of finding asteroids, it’s really important that we know the distribution of diameters and the distribution of albedos,
Myhrvold says. Albedo is the reflectivity of the surface of an asteroid, which determines how easily it can be detected.
NASA has said that the diameters of asteroids made by NEOWISE are generally within 10% of the actual size. Myhrvold points out that the uncertainties are greater, even more than 100% in some cases.
Officials from NASA have disagreed. “He’s a very smart man,” says Dr. Lindley Johnson, who oversees NASA’s projects to protect Earth from Asteroids. “But that doesn’t make him an expert in everything.” Johnson adds that NASA experts had highlighted some errors that Myrhvold has not fixed. “It’s overly simplistic, and he makes some assumptions that are not valid.”
However, other scientists think that there may be some validity to Myhrvold’s observations.
Dr. Alan W. Harris, a senior research scientist at the pace Science Insitute says that, “I do think he’s performed a really very useful service to do the error analysis more carefully and alert people that you shouldn’t just take some of the data out of the WISE table and just assume they’re gospel.” Harris notes that even if Myhrvold is correct, the NEOWISE data “has good enough validity to be useful for most purposes.”
Myhrvold is not an astronomer and has never done research on asteroids, but was drawn into the field when a nonprofit organization asked him to finance Sentinel, a private asteroid-finding spacecraft.
Myhrvold observed that the albedo calculations done by the Neocam team violated a tenet in physics known as Kirchhoff’s law of thermal radiation. He then took a closer look at NEOWISE and did some calculations of his own. He has submitted his analysis of the NEOWISE data to the journal Icarus.