Falling from space, Lagrangian points and planetary assassins, the upcoming Large Synoptic Survey Telescope

Saturday, March 07, 2009

Figure 1. The 300-ton Large Synoptic Survey Telescope (LSST) structure is an elevation-over-azimuth configuration, constructed of pure awesome.

Three things to show today that I don't think I can write an entire post on but are worth sharing:

First of all, a video from 2006 that is worth checking out if you've never seen it before. This is what it's like to be an SRB (solid rocket booster) on the Space Shuttle, then ejected and fall back down to Earth:

Next is an interesting article from February about Lagrangian points and what they might hide. Lagrangian points are five points present between two bodies where their gravity cancels each other out and thus there is no pull to one side or another. This gravitationally stable area is a great place to locate certain probes, and a number of things could be hiding in them that we've never discovered. Here's why:
Of the five Lagrangian points, L4 and L5 are the most intriguing. They are the only ones that are stable: while a satellite parked at L1 or L2 will wander off after a few months unless it is nudged back into place, any object at L4 or L5 will stay put due to a complex web of forces. Lying 150 million kilometres away, along the line of Earth's orbit, L4 circles the sun 60 degrees in front of our planet while L5 lies at the same angle behind.
Here's where L4 and L5 are located:

Distance-wise that's not very far, so why haven't we been able to discover anything there as of yet?
The trouble is that our L4 and L5 points are not easy to see from the ground. They appear to lie close to the sun, so by the time night falls, the trailing L5 region is low in the sky and setting fast. On the other side of the sky, the preceding L4 point rises in darkness but the dawn is hot on its heels.
Then it gets into the STEREO probes and why there's a great deal of expectation about being able to find objects at the L4 and L5 points thanks to the probes (the explanation is pretty long so I won't try to do it here), and finally about the maximum size of any objects in this area:
No one knows how many asteroids the STEREO probes will see. Weigert and colleagues have performed a number of computer simulations that showed how asteroids can be nudged from a Lagrangian point due to Venus's gravity; it can happen on a timescale of a million years or so. However, the same simulations showed that this works both ways, with asteroids being nudged into the Lagrangian points by Venus as well. These results, and the failure of telescopes to find a Lagrangian asteroid to date, have made Weigert cautious about the number and size of the asteroids he expects STEREO to find. "I think there may be a few asteroids, but not hundreds, and I'm thinking that they are less than a kilometre across. In the main asteroid belt, a typical asteroid is 100 kilometres across."
and a ton of other information. Definitely get a cup of coffee and take the time to read the whole article if you're interested; it's very interesting.

Finally, an article here on The Large Synoptic Survey Telescope, which is partially funded ($10 million) by none other than Bill Gates:
The Large Synoptic Survey Telescope (LSST) is a new ground-based telescope designed to address some of today's most compelling questions in astronomy and high-energy physics. During its planned ten-year survey operation, it will map the visible sky deeply, rapidly, and continuously, producing an archive of hundreds of images covering the entire sky. The same data set can be used to characterize the properties of dark energy, produce nearly instant alerts of serendipitously detected optical transients (such as exploding stars in distant galaxies), discover and provide orbits for potentially hazardous near-Earth objects, and catalog billions of targets with high astrometric precision and to unprecedented photometric depths. By publishing the images, alerts, and catalog products (without any proprietary period), the LSST will transform the way astronomers and high-energy physicists conduct research.
That last sentence is what makes it particularly interesting. As this article states:
LSST is designed to be a public facility. The database and resulting catalogues will be made available to the public with no proprietary restrictions. A sophisticated data management system will provide easy access, enabling simple queries from individual users. The public will actively share the adventure of discovery.

A great deal of objects (comets / asteroids) are discovered by SOHO thanks to average people poring over images and looking for anything out of the usual, and this shows just how much unanalyzed data there is that the public really should have access to.


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