Tag Archives: engineering

A ground-based telescope matches the Hubble Space Telescope-NOT

Correction.Regular reader James Fincannon emailed me to say that he thinks the image below is an artist’s impression. He is correct. I should have looked more closely at the press release. In reading the actual research paper [pdf] on the results it seems that the VLT did some very sophisticated spectroscopy, thereby measuring the uneven distribution of the velocity and density of the gas around the star. The image below was then created, based largely on Hubble images combined with the new data. In other words, this ground-based telescope did not match the abilities of a space-based telescope in any way. Had the Hubble images not existed the astronomers would have struggled to interpret their spectroscopic data.

Some important astronomy news: The European Southern Observatory’s Very Large Telescope (VLT) has released this spectacular image of supernova 1987a, the first and so far only supernova visible to the naked eye since the invention of the telescope.

SN1987a

This image is important for two reasons. First, The data shows that the supernova explosion was not symmetrical, with more material being thrown outward in some directions than in others. This fact confirms what astronomers in recent years have increasingly come to believe: Supernovae explosions are not simple spherical bursts, but chaotic events ripping stars apart in a lopsided manner.

Second, this image demonstrates that ground-based telescopes are becoming amazingly good at doing what the Hubble Space Telescope has done routinely for the past two decades. Five years ago, no telescope on the ground could have resolved the inner ring of supernova 1987a. Only Hubble in space had that capability. Now, VLT can do it, almost as well as Hubble. Though a space-based telescope can still beat any ground-based telescope, it is great news that the technology for ground-based telescopes has improved so much, especially since there presently are no plans to replace Hubble.

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Burt Rutan on future of space

At an airshow on Thursday, July 29, in Oskosh, Wisconsin, Burt Rutan, designer of SpaceShipOne, made some interesting remarks about the past and future of private space flight. Key quote:

Rutan said NASA should give 10 to 15 percent of its budget to new space companies like Elon Musk’s SpaceX without regulating how to spend the money. “That would allow them to not (have to) beg for commercial investment, while still working in an entrepreneurial mode.”

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Solar sail conference

Solar sail engineers from around the world gathered in Brooklyn last week for the Second International Symposium on Solar Sailing. Ben Diedrich, fellow caver, solar sail expert, and the man behind wiki.solarsails.info, gave two papers. He also emailed me to say that “Japan’s contingent gave several talks – many of which compared analysis of deployment, flight, or steering with actual flight data” of Ikaros. A review of the program [pdf] revealed some fascinating uses for solar sails. I like this paper title the best: “Deflecting Apophis with a flotilla of solar sails.” [ed. Apophis is an asteroid with the potential of hitting the Earth.]

Update: Japanese scientists have now announced that they have been able to adjust Ikaros’s attitude using sunlight.

Another update: Ben Diedrich emailed me the link to read the actual proceedings from the conference. See pg 103 to read the paper on using solar sails to deflect Apophis.

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Single Rope Techinque — on the Moon

James Fincannon of NASA took the two images of the Marius Hills lunar pit taken at different times by Lunar Reconnaissance Orbiter (which I posted here) and did an overlay so that the shadow produced by pit’s rim could be easily compared with the rim itself (see below). He then did some calculations based on the sun’s angle of light shining into the cave and came up with the following calculations:

I estimate it is 60 meters from rim to bottom. The floor is flat below the surface. The rocks on the flat surface below ground are in stark relief (hard shadows) compared to above ground due to the sun coming only at one angle while above ground the albedo/reflections makes for soft shadows at this high sun angle (65 deg elevation). I cannot tell if the black portion of the combo image is a slope or more flat floor. Need a different high sun angle or azimuth to fill that in. Still I like the general pattern of the rim matching the shadow on the floor, although the image I found originally has that edge of the cave rim in shadow for a large extent.

overlay of Marius Hill cave

A 60 meter drop is about 200 feet deep. This result is reasonably close to the depth estimated by Japanese scientists, 88 meters or 288 feet, based on images of the same lunar pit taken by their Kaguya probe.

Knowing the approximate depth of the entrance pit raises the much more important question: How will future lunar explorers to get to the bottom of this pit? It is ironic » Read more

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Solar powered plane flies for two weeks

Zephr, a British-built solar-powered unmanned plane was ordered to return to Earth after flying continuously for two weeks without refueling. Key quote:

Zephyr is set to be credited with a new world endurance record (336 hours, 24 minutes) for an unmanned, un-refuelled aircraft – provided a representative of the world air sports federation, who was present at Yuma, is satisfied its rules have been followed properly.

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