Asteroid diameters: scientific controversy?

[JeanTate]

I couldn't see that this topic has already been covered here, so I started this new thread. If it's already a topic, could a mod please merge it with the appropriate thread? Thanks.

Nathan Myhrvold is pretty well-known, I hope.

A month or so ago there was a bit of a flap over what he wrote, concerning a paper he's submitted to Icarus (preprint is on arXiv, arXiv:1605.06490; link is to the abstract); here's how he characterizes the flap.

It - the controversy - is discussed in quite a few places; I'd recommend Peter Woit's Not Even Wrong blog post on it, Killer Asteroids (when you read the comments you may guess why I favor this site! ).

Anyway, this appeared on arXiv today (arXiv:1606.08923): "NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos". The abstract is worth copying in full:

The Near-Earth Object Wide-Field Infrared Survey Explorer (NEOWISE) mission continues to detect, track, and characterize minor planets. We present diameters and albedos calculated from observations taken during the second year since the spacecraft was reactivated in late 2013. These include 207 near-Earth asteroids and 8,885 other asteroids. 84% of the near-Earth asteroids did not have previously measured diameters and albedos by the NEOWISE mission. Comparison of sizes and albedos calculated from NEOWISE measurements with those measured by occultations, spacecraft, and radar-derived shapes shows accuracy consistent with previous NEOWISE publications. Diameters and albedos fall within ±∼20% and ±∼40%, 1-sigma, respectively, of those measured by these alternate techniques. NEOWISE continues to preferentially discover near-Earth objects which are large (>100 m), and have low albedos.

"Comments: Accepted to AJ"

The status of Myhrvold's paper? Apparently not yet accepted for publication (I have no way to tell, for sure).

Worthy of a discussion here, I think.

In particular, what's your take on what Myhrvold identifies as "the problem"?

And which of his three suggested explanations - "Colossal error", "Fraud", or "Something else" - do you think holds the most water (and why)?

 

[GodMark2]

http://www.slate.com/blogs/bad_astr...ists_asteroid_calculations_are_all_wrong.html

Short answer: He doesn't understand how this particular science works, thinks his intuition must be correct, and therefore "scientists are lying to you".

The errors she(Amy Manizer) mentioned are various, including his(Myhrvold) confusing diameter with radius in his calculations and using a model that incorrectly determines diameters

The real scientists used IR measurements of asteroids to which the distances and sizes are known by other means (Radar, occulations, etc) to calibrate the IR signature, and used that to estimate the size of other objects. Myhrvold assumed that all asteroids must be perfect blackbodies and did some math (in which he additionally made some elementary errors, like confusing radius and diameter).

 

[Genesius]

Phil Plait covered this a month ago: http://www.slate.com/blogs/bad_astr...ists_asteroid_calculations_are_all_wrong.html

TL;DR version: Myrhvold is wrong.

 

[Reality Check]

Nathan Myhrvold is pretty well-known, I hope.

Actually Nathan Myhrvold is quite obscure in science. ADS has another 2016 paper and his non-astronomy thesis in 1983. Nathan Myhrvold has a 1983 thesis in Quantum Field Theory and then writes a couple of astronomy papers 33 years later. He worked in the computer industry (lots of patents for Microsoft) and is now basically a venture capitalist.

That 33 year gap explains why Nathan Myhrvold could make basic mistakes as pointed out by Phil Plait's article.

His one published astronomy paper is Comparing NEO Search Telescopes, Publications of the Astronomical Society of Pacific, Volume 128, Issue 962, pp. 045004 (2016).
This paper is cited in Modeling the Performance of the LSST in Surveying the Near-Earth Object Population, The Astronomical Journal, Volume 151, Issue 6, article id. 172, 8 pp. (2016).

The limiting magnitudes and solar elongation coverage presented here are at odds with Myhrvold (2016); his Figure 7 shows much fainter limiting magnitudes than presented here. While Myhrvold (2016) cites the possibility and capability of LSST observing at much smaller solar elongations, this is inconsistent with the published cadences provided by the LSST project and would potentially interfere with its other science goals. Additionally, Myhrvold (2016) incorrectly assumes that an object need only be detected once for it to be counted as discovered, cataloged, and tracked.