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Nathan Myhrvold: 'Nasa doesn't want to admit it's wrong about asteroids'
Nathan Myhrvold is the former chief technology officer of Microsoft, founder of the controversial patent asset company Intellectual Ventures and the main author of the six-volume, 2,300-page Modernist Cuisine cookbook, which explores the science of cooking. Currently, he is taking on Nasa over its measurement of asteroid sizes.
For the past couple of years, you've been fighting with Nasa about its analysis of near-Earth asteroid size. You've just published a 33-page scientific paper [open, DOI: 10.1016/j.icarus.2018.05.004] [DX] criticising the methods used by its Neowise project team to estimate the size and other properties of approximately 164,000 asteroids. You have also published a long blog post explaining the problem. Where did Nasa go wrong and is it over or underestimating size?
Nasa's Wise space telescope [Wide-field Infrared Survey Explorer] measured the asteroids in four different wavelengths in the infrared. My main beef is with how they analysed that data. What I think happened is they made some poor choices of statistical methods. Then, to cover that up, they didn't publish a lot of the information that would help someone else replicate it. I'm afraid they have both over- and underestimated. The effect changes depending on the size of the asteroid and what it's made of. The studies were advertised as being accurate to plus or minus 10%. In fact, it is more like 30-35%. That's if you look overall. If you look at specific subsets some of them are off by more than 100%. It's kind of a mess.
[...] Nasa's reported response has been to stand by the data and the analysis performed by the Neowise team. Can we trust Nasa after this?
They need to have an independent investigation of these results. When my preprint paper came out in 2016, they said: "You shouldn't believe it because it's not peer-reviewed." Well, now it has been peer reviewed. How Nasa handles it at this stage will be very telling. People have suggested to me the reason Nasa doesn't want to admit that anything is wrong with the data is that they're afraid it would hurt the chances of Neocam, an approximately $500m (£380m) telescope to find asteroids that might hit Earth proposed by the same group who did the Neowise analysis.
Previously: Former Microsoft Chief Technologist Criticizes NASA
(Score: 0) by Anonymous Coward on Monday June 25 2018, @01:49PM (2 children)
He did collect all the data into his own database and released his own analysis. What exactly do you think is missing?
(Score: 1, Informative) by Anonymous Coward on Monday June 25 2018, @03:50PM (1 child)
Note that I have no affiliation with NASA or Myhrvold, but this story has been bugging me.
I see the Mainzer team's papers with a bunch figures and text that describe how to relate WISE images to real asteroid diameters, which is a tricky process. I see Myhrvold spending all of his ink complaining that they didn't do it right.
One complaint seems to be that a table they published contains D values (diameters) from radar observations rather than from their WISE images. Presumably, the NASA people wanted to but the best available diameter in the table (not unreasonable). Apparently they should have been more clear about the source of D, or kept one column for WISE-based D and one for radar-based D. Oh well, the perfect is the enemy of the good.
Another complaint is that the "fits miss all the data points" in some cases, and Myhrvold equates this to data fabrication. If a large part of the database were based on garbage fits, that would be a reasonable criticism. But I don't see any evidence of that. The NASA analysis does include error bars for each asteroid, and a lousy fit will show up as a big error bar.
(Score: 0) by Anonymous Coward on Monday June 25 2018, @07:17PM
whats this have to do with "put up or shut up"?