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The Planetary Society BlogBy Emily Lakdawalla
Feb. 3, 2012 | 12:09 PST | 20:09 UTC The Arecibo TripBy Bill Nye Audacious— that's how I describe the Arecibo radio telescope. For me, it was just hard to believe what I was seeing. I have just returned from my first Planetary Society-sponsored trip to Puerto Rico and this historic, remarkable, big idea of a telescope.
If you're not familiar with this machine designed to explore the cosmos and our own ionosphere, it was conceived in 1958, built by 1963, upgraded and refined in the decades since. The premise of the story (as we say in writing) was to build a telescope so big that it could and can detect electromagnetic signals at astonishingly low energy levels. These would be signals emanating from high in our own atmosphere as well as from fantastic astronomical distances. The reflector of this machine is too big to move. It fills a whole valley– an ancient sinkhole actually, a bowl created by the collapsed roof of an ancient underground limestone cave. The valley has been fitted with a reflective section of a sphere 1000 feet (305 meters) across that's round to within plus-or-minus 1.5 millimeters (1/16th of an inch). It is amazing in its construction. But for me, the more amazing aspect of the machine is the conception, the idea that humans could build such a thing— and have it work.
The receivers above the reflector are suspended on an almost crazy system of wire ropes (twisted steel cables) and pulleys. The receiving and broadcasting antennae for this thing are enormous. They appear to be suited for the Jolly Silver Giant, were he to exist, of radio astronomy. With a sphere for a reflector, rather than a parabola, the antenna is a stick… 25 meters long. Or, it's a detector big enough for a family of four to camp out in comfortably. This machine not only receives deep space waves; it can create them. In a separate building, we have a microwave-making klystron. High above the big dish, are two other klystrons in tandem. They're just like the one in your microwave oven; only these reckon their power in Megawatts. Radar signals can travel to 100-kilometer-diameter asteroids, millions of kilometers away, and record surface features just a few meters across— all in less than a second. When investigating Saturn, the astronomers have to plan for the Earth rotating as they wait the hour and a half for the electromagnetic waves to make the trip there and back. The wave-guide for the signals travels 1600 feet of perfectly machined square tubing. Its interfaces transmit microwaves, like in your oven, only these go into deep space with barely 3% of loss. The whole machine with its accompanying instruments and its dedicated staff is audacious. It's the work of a citizenry dedicated to exploration and learning more of our place in space. It is the product of the best use of our intellect and treasure. If you have a chance, consider a trip with the Planetary Society. We'll take you to remarkable places like the Arecibo telescope. There are many worlds out there; to learn about them, try a trip around ours.
Feb. 3, 2012 | 09:02 PST | 17:02 UTC Guest Post: Patrick Donohue: Six days in the crater (day one)Patrick Donohue is a fourth-year Ph.D. student working with Clive Neal at the University of Notre Dame, whose primary research focus is on the origin and evolution of high-titanium lunar basalts. He writes a geology blog and is active on Twitter under the username poikiloblastic. He's also an amateur photographer, shooting sports, and wildlife, and of course interesting geology! The following is the first in a series of posts based on field notes and memories supplemented by background reading material from the Meteor Crater Field Camp that was held from October 17-23, 2010. The field camp was run under the NASA Lunar Science Institute and headed by Dr. David Kring of the Lunar and Planetary Institute. I thank Patrick for permitting me to repost these entries from his blog. --ESL
Twenty-two of us are spread out between three Chevy Suburbans, and it's strange having legroom on a geology expedition. Not that there's far to go. We are camped out in an RV park a mere 5.5 miles from our field site: Barringer Meteorite Crater. This is the first day of the first ever Meteor Crater Field Camp, and we are making the first trip first thing in the morning to my first visit to any crater, ever. Everyone's ready to get started, and we don't have long to wait. Our first stop is approximately fifteen feet outside the gates of our campsite, and we step out of the vehicles after realizing the stop wasn't because of a forgotten water bottle or notebook.
We learn we wouldn't even last that long. At this distance the shock wave would reach you in less than a second, turning you inside out before the wind and heat simultaneously flash-cooked your body as it tumbled away in pieces with the desert sage. Oh well. Someone luckier and further away would have seen quite the show. 49,000 years later, as we pile back into the vans, it's mostly sunny and warming past 50°F on the high desert plains of Arizona. [*On the basis of thermoluminescence, 26Al, 10Be, and 36Cl studies, it's generally agreed that Meteor Crater formed 48 to 49 thousand years ago. More recently, updated 36Cl reference material argues for an older age of 60 to 65 thousand years.] On the docket for our first day at the crater is a 3.7 kilometer (2.3 mile) hike along the rim, about 1.8 km clockwise before lunch, then retracing our steps counterclockwise. There's House Rock (also known as Monument Rock), the largest (intact) boulder on the crater rim at about 10 meters tall. Pile on two more House Rocks and you'd have a reasonable estimate of the meteorite diameter. And maybe at one time there really was another House Rock or two on top. Surface exposure age dates from the top of House Rock are younger than the 49,000-year formation age.
On our counterclockwise hike back we generate a little erosion of our own by scrambling down the crater wall a bit from House Rock to see something (else) awesome. We start out on Kaibab limestone on the crater rim and walk down through Moenkopi formation, and end up back at Kaibab. The top slice of bread in the Kaibab-Moenkopi-Kaibab sandwich is ejected, overturned Kaibab. The bottom slice is in-situ Kaibab. And the meaty Moenkopi center is where it gets interesting. Look at the photo below. Both members of the Moenkopi are visible here. The pale reddish brown Wupatki (at left) is a massive sandstone underlying the dark, reddish brown fissile siltstone called the Moqui. The surrounding pale/tan blocks are dominantly Kaibab (limestone/dolostone), though most shown here are loose boulders.
Feb. 2, 2012 | 15:06 PST | 23:06 UTC SpaceUp unconference in San Diego on SaturdayThis weekend is SpaceUp unconference in San Diego, and I'll be attending on Saturday. I've never been to an unconference before, so I'm very curious to see how it all works! You can still register if you want to attend, but if you can't, some part of the unconference will be webcast on Spacevidcast. As per the unconference format, there is no set agenda yet, except for Saturday evening from 7:00 to 9:00 p.m. Pacifc, when there will be a series of T minus 5 talks. These are talks in which the hapless presenter is allowed 20 slides which rotate automatically every 15 seconds, described as "more like karaoke than giving a presentation," and I have foolishly agreed to give the first one. Wish me luck, and watch how I fare via the webcast! Or watch the #SpaceUp #SD hashtags on Twitter. And learn more about unconferences and SpaceUp in particular on last week's Planetary Radio interview of Chris Radcliff and Marimikel Charrier.
Feb. 2, 2012 | 14:33 PST | 22:33 UTC Yay for Juno! First major course correction completeJPL issued a news note today with that most dreaded of press release titles: "Mission Status Report," which I dread because it's usually a euphemism for "something bad has happened to one of our spacecraft." But this time it contains nothing but good news. It briefly notes that the Jupiter-bound Juno spacecraft has successfully completed the first of twelve trajectory correction maneuvers it'll perform between launch last year and Jupiter arrival in 2016. Its next maneuver will take place in August of this year. Go Juno!
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