Lick Observatory

Lick Observatory, pictured above, is situated in the mountains east of San Jose, and when it was constructed in 1887 it was the world’s largest refracting telescope (a title it held for about 10 years).  Its benefactor, James Lick, made his fortune buying up real estate during the California Gold Rush (and incidentally, was the one who convinced his Peruvian friend Ghirardelli to move to California and start selling chocolate).  According to the historian-in-residence, the 40-tonne telescope itself is so finely balanced that it can be turned around by hand.  Though to reach the eyepiece, you need to move up the entire wooden floor surrounding the base of the telescope, a feat that’s possible through a mechanical water elevator.

The observatory also recently dug up the only known seismogram of the 1906 California earthquake recorded in North America:

As it turns out, 2009 marks the 400th anniversary of Galileo‘s telescope (though he wasn’t the first to invent one – historical evidence suggests that honor goes to either Hans Lipperhey or Zacharias Janssen).  The progress of astronomy over time could be measured by tracking the resolving power or light-gathering ability of telescopes built:
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A telescope’s ability to detect fine detail in object at distance is known as resolution or resolving power… resolution is inversely proportional to the size of a telescope’s primary mirror.  A 5-inch telescope… could distinguish two quarters placed an inch apart from 3 miles away.  A 1.3-meter telescope could distinguish heads from tails on the quarters.  A 10-meter telescope could read the letters on the quarter spelling out ‘in God We Trust’… bigger telescopes can also see fainter objects.  The light-gathering ability is determined by the area of the primary mirror.” – Robert Duffner, the Adaptive Optics Revolution

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Based on the list here, you can see the progression over time:

One should note that most of the new telescopes achieve their apertures through either segmented mirrors (a bunch of small mirrors put together) or optical aperture synthesis (mirrors separated by some distance joining to create a single image through interferometry) – simply because it’s prohibitively expensive to make large, smooth, light-weight concave mirrors with the accuracy demanded by telescopes (the mirror surface for one of Keck’s telescopes required ion milling to within a few nanometers).  Even with all this, if it weren’t for adaptive optics, the huge telescopes would be generating blurry images due to atmospheric turbulence (which is why astronomers tried to bypass this by creating Hubble and launching it into space).  It was originally thought of by Horace Babcock in 1953, developed by DARPA at the Starfire Optical Range, and improved by Will Harper’s sodium waveguide laser concept.  Modern telescopes also use liquid-nitrogen-cooled CCDs (which increases their sensitivity to photons) to capture digital images of the stars.

What’s next?  The 30-meter telescope on Mauna Kea, the Giant Magellan Telescope (a description of how they make their mirrors), the James Webb Space Telescope (the successor to Hubble).  In addition, alternative designs using liquid mirrors and membrane mirrors are being developed.

bad statistics

There was something bothering me a few weeks ago about an argument I remembered from James Surowiecki‘s book, the Wisdom of the Crowds, which is surprising as I had read it about two years ago.  It regards the passage below, from page 8:
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What this means is that the stock market had, almost immediately, labeled Morton Thiokol as the company that was responsible for the Challenger disaster… the steep decline in Thiokol’s stock price – especially compared with the slight declines in the stock prices of its competitors – was an unmistakable sign that the investors believed Thiokol was responsible… on the day of the disaster there were no public comments singling out Thiokol as the guilty party… regardless, the market was right… six months after the explosion… Thiokol was held liable for the accident.

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First off, the word “competitors” is not accurate – because the correct comparison to be made is to other companies who manufactured parts for the space shuttle, not companies who were competing with Thiokol but had nothing to do with the spacecraft; but no worries, the paper he cites is a-OK in this regard.

The claim being made is that because the stock price of Thiokol went down further than the other manufacturers, the market must have “known” they were guilty.  Given the nature of insider trading, this is a possibility.  But can you make such a claim from the evidence?

Let’s look at the data, then: a few of the large companies that built components for the space shuttle included Lockheed, Martin Marietta, and Rockwell International.  Here are graphs of the stock prices, and traded volumes, of their ticker symbols (LK, ML, and ROK, respectively, along with Thiokol’s MTI) the month of the disaster (thanks to my friend Salman for digging up some of the historical data for me – the horizontal axis is in days the stock market was open, so day -18 is January 2, 1986):

while all 4 stocks have a jump in volume on the 28th (the day of the disaster), Thiokol’s certainly does dip lower than the rest.  According to the paper written by professors Mulherin and Maloney, Thiokol dipped 12% compared to 3% for the others.  They mention that the “data show no evidence of trading by insiders on January 28, 1986,” yet go on to make the claim that there was “no ambiguity that the stock market quickly isolated Morton Thiokol as the cause of the accident.”  Moreover, “the fact that market liquidity was available to maintain a market in Lockheed, Martin Marietta, and Rockwell while the market for Morton Thiokol dried up suggests that the stock market discerned the guilty party within minutes of the announcement of the crash” (an older draft of the paper used “is evidence that” in place of “suggests that”).

Even if it was statistically significant, I’d say the evidence is still inconclusive, simply because you can’t rely on correlation to be anything more robust than an indicator.  Perhaps I should proffer an alternative explanation for the larger fall in Thiokol’s stock price, then?  How about, Morton Thiokol was a much smaller, less-diversified company than any of the other three, and had the most to lose from the space shuttle disaster?  If I could get my hands on some of the annual reports to see what percentage of their revenues come from NASA contracts…

Nevertheless, I don’t think the argument holds water.  But I do love it when people anthropomorphize the markets

the Stock Market Reaction to the Challenger Crash

Steve Squyres talks about the Mars rovers

Prof. Steve Squyres from Cornell delivered an awe-inspiring lecture a few months ago about his work on the NASA Mars rovers, and later signed his book for the audience.

or download the MP3 here.

It was cool how he made a point of answering questions from children in the audience first – a true successor to Carl Sagan. I wanted to ask him how they navigate if there is no GPS system on Mars – it seems like this is the answer, which would have to be supplemented with visual calibration of some sort.  As Mars has days shorter than here on Earth, every team member had specially-designed watches made that would run on Mars time, bringing them into work half an hour earlier every day!

You can download and play around with the software that the engineers at NASA use to control the rovers, using real data.  You can fly around Mars as well, using digital elevation data with software like this or this.  Astronomy is becoming more accessible now thanks to Microsoft’s WorldWide Telescope and Google Sky.

Most of the deep-space probes actually only send data using a single radio sideband in order to save power, and are received through the Deep Space Network (I visited the Goldstone site in the Mojave desert outside L.A. a few years ago, which is actually situated on the live-fire Ft. Irwin military base).

Here are some of the pictures/videos from his slide deck:

sunset on Mars:

dusty solar panels:

purgatory dune (video of the wheels burning rubber here)

the landing site:

soil test:

parachute testing in the wind tunnel at Moffett Field (they have great tours)

Mars rover petals unfolding

wheels burning rubber

dust devils on Mars:

the Mars 2020 video referred to in the Q&A session is here.