A Launch to Remember (Part 6) April 30, 2011Posted by Lofty Ambitions in Space Exploration.
Tags: A Launch to Remember, Space Shuttle
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Saturday Afternoon: Yesterday was a very long day for us. You’d think that a scrub shortly after noon, shortly after the excitement of witnessing the crew walkout, would mean that we could kick back for the rest of the day. But whenever there’s a significant change in plans, the Kennedy Space Center (KSC) Press Center schedules a briefing at some point. We wanted to stay for that. Besides, we were concerned about traffic. The driver of the bus back from the crew walkout to the Press Center said that he had a long shift ahead of him but that he didn’t mind because he imagined that it would take four or five hours for some of the people who were heading out right away to get home. Indeed, one photographer staying at a hotel about a dozen miles away from the Press Center spent about 90 minutes getting back to his room, and he waited until after 4p.m.
Yesterday’s press briefing was delayed a bit, so that it could focus on two things: the political, or President Obama’s visit to KSC and Representative Giffords’s plans, and the procedural, or what it will take to get Endeavour ready to fly. While we were happy to see the president’s helicopter land behind the Vehicle Assembly Building across the street from the Press Center and then see his motorcade drive by, that wasn’t really our bailiwick for our blog. The procedural boils down to repairing a malfunctioning heater in the orbiter’s left APU, or Auxiliary Power Unit.
As we listened to Launch Integration Manager Mike Moses and Shuttle Launch Director Mike Leinbach, we understood that the problem was either a faulty thermostat, which could be relatively easily switched out, or the larger line of heaters on string B that wraps around a hydraulic fuel line. Had they discovered this problem once in orbit, they would have burned off that system and gone on their way, but the concern about flying with this known problem is the possibility of a frozen line, the possibility that a frozen line would thaw at some point after pressure had built up, and the possibility that a thawed line could catch fire during reentry. This problem meant they were in violation of launch criteria and the decision to scrub was “straightforward” according to both Moses and Leinbach.
We hope that a faulty thermostat is the problem. Leinbach pointed out that changing out the larger system, the box that houses various parts, would take an additional two days of retesting after the fix itself is completed. That would make a Monday or Tuesday launch an impossibility, and then KSC runs into a conflict with the Air Force, which is launching an Atlas rocket this week. If they must delay, they also have to look at the whole mission schedule so that undocking from the International Space Station in preparation to return to Earth doesn’t fall on the same day as the scheduled Soyuz undocking. It’s a complicated syncing up.
We’re now in the Press Center, where we just received the inside scoop that workers have entered the aft section of the shuttle, where the heater is located. It took them a full day to get into the shuttle to take a look because, once the external tank is full of fuel, it takes 24 hours to drain it and let the remaining hydrogen evaporate. In addition, they had to roll the Rotating Service Structure back into position to provide access to the shuttle. We’re hoping that another update is available on the KSC website at about 4:30p.m., or shortly after the Press Center closes for the day. In the meantime, we’re heading to the KSC Visitor’s Complex for further research.
A Launch to Remember (Part 5) April 29, 2011Posted by Lofty Ambitions in Space Exploration.
Tags: A Launch to Remember, Serendipity, Space Shuttle
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Friday at 1:30p.m.: We went to the STS-134 crew walkout! Woohoo, we saw all the astronauts in their orange launch suits!
We have lots to say about the crew, even though, as we rode the bus back to the Press Center, we heard news that the launch was scrubbed until at least Monday. We are unfortunately familiar with this news, as a result of our experience last November. As you might expect, this news isn’t slowing us down. We have a few one-on-one interviews scheduled, and we want to share some info about the six-man crew of STS-134.
STS-134 is all men this time. Mark Kelly, the husband of Congresswoman Gabrielle Giffords, is the mission’s commander. We’ve written about him before HERE and HERE. He’s flown three previous shuttle missions—two on Discovery and one on Endeavour—and logged 38 days in space.
Greg Johnson is the pilot for STS-134 and was the pilot on a mission in 2008. Andrew Fuestal is one of the mission specialists, was on the shuttle’s last servicing mission to the Hubble telescope, and will be doing several EVAs, or extravehicular activity spacewalks. Greg Chamitoff is another mission specialist and previously served on the International Space Station (ISS). Roberto Vittori is the Italian on board this mission and has flown to the ISS twice before.
Our favorite astronaut on this mission, though, is Mike Fincke. His early education and career did not foretell great success. In an interview that aired on NASA-TV, Fincke admitted that his grades were not always stellar, and he’d known a C or two along the way. Even worse, he washed out of pilot training. Even worse than that, the day he washed out of pilot training was his birthday.
He attributes his ultimate success as an astronaut, in part, to five years of studying Latin. He said that made learning Russian much easier, and learning Russian allowed him to travel to the ISS and also become qualified to fly as a left-seat flight engineer on Russian Soyuz spacecraft. And he speaks Japanese fluently too.
Fincke’s enthusiasm is obvious and often punctuated with a grin that exudes childlike glee. This guy never gave up. When he washed out of flight training, someone suggested he think about engineering, so he gave that a whirl. He was ambitious, but more than that, he’s not easily daunted.
What’s especially interesting is that, upon completion of STS-134, Mike Fincke will hold the American record for number of days in space, as a result of his two stints on the ISS. He shrugs at the milestone, pointing out that Russians have well surpassed the hours in space he’s logged. The interesting part of his American record, though, is that Fincke has never before flown on the space shuttle and will be listed as the last-ever shuttle astronaut. While Roberto Vittori hasn’t flown a space shuttle mission yet either, their mission specialist designations place Mike Fincke behind Vittori, and all the STS-135 crew have flown shuttle missions before.
That’s just the kind of who’d-have-thought serendipity story that Lofty Ambitions likes: the guy who washes out of flight school ends up holding the American record for time in space and gets listed as the last space shuttle astronaut ever.
A Launch to Remember (Part 4) April 29, 2011Posted by Lofty Ambitions in Space Exploration.
Tags: A Launch to Remember, Space Shuttle
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Friday 9:30a.m.: The KSC press rooms are buzzing now. The folks with the big cameras are busy setting up. Reuters and CBS are the only news organizations with permanent structures, so they have rooftop viewing posts. We’re sitting next to the reporter from the Miami Herald.
For those of you who know Anna personally, you can imagine her panic when she discovered that the beverage vending machine was sold out. Luckily, the snack truck arrived at 8am with cans of Diet Coke. Rest assured that Lofty Ambitions has recaffeinated and will schedule another break at the appropriate time.
We’re unlikely to be able to see the astronaut walkout. The Press Center posted the sign-up sheet yesterday morning, and the 150 spaces filled up quickly. We’re on a standby list, but there are about a dozen people ahead of us and even more behind. The press officer who manages the launch events for us said that, in his memory, they’ve never taken 150 members of the press out to see the astronauts wave on the short walk from the suit-up room to the van that takes them to the launch pad. Another reporter just said that he’s on the list to go to the walkout, but he can’t imagine that they’ll be able to fit 150 people in the space for the press there, and it’s a lot of effort for a few seconds of waving. Still, since we haven’t seen astronauts in launch suits up close and personal, it seems pretty appealing to us.
We’re also unlikely to have coffee with the president, but we’ll see what happens. The KSC Press Center doesn’t know anything about the president’s schedule. We imagine that the White House coordinates their own press corps traveling with President Obama. He has a busy schedule today, with a stop in Tuscaloosa to survey storm damage and speak with residents there as well as his stop here for this afternoon’s launch.
We’re having a great time despite these possible missed opportunities. We picked up the official photos of the STS-134 crew (we’ll have more on the crew later), Endeavour on the launch pad, and Discovery landing. We also picked up a couple of stickers of the STS-134 official patch.
The weather is looking to be relatively good for launch. There’s a 30% chance that clouds or wind could be a problem, but the talk is positive. If you judged by the way the sky has looked these past three hours, though, you’d have trouble believing the optimism.
The countdown clock just hit the three-hour mark, which signals a built-in hold. There are seven planned clock-stops in this launch countdown.
A Launch to Remember (Part 3) April 29, 2011Posted by Lofty Ambitions in Space Exploration.
Tags: A Launch to Remember, Space Shuttle
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Thursday at 9:20p.m.: Already, this launch feels markedly different than our visit last November for what has become known around Lofty Ambitions as the not-launch. Getting off the plane this time brought with it waves of that famous Florida humidity. Last fall, the Space Coast was actually a bit chillier than our adopted Southern California home. The differences kept piling up.
Last fall, the drive across the parkway was dark and solitary. This time, we faced a nonstop display of lightning illuminating hundreds of cars sharing the road with us. The car rental agent quipped that he’d checked in a party of thirty Brazilians the day before, all here to see the launch.
As we pulled into our familiar Titusville Super 8, we were stunned to find that the mom-n-pop Italian restaurant, Jimmy and Cora’s II, where we had eaten every dinner during our last trip, was gone, replaced by the Garden Club. While Anna checked in, Doug grabbed a table at the restaurant. It still served Yeungling on tap.
We would have posted this after dinner, but we were tired, and the hotel wireless connection wasn’t cooperating, perhaps because of the rough weather. Some things feel the same, but we’re hoping for a different outcome.
Friday 7:15a.m.: We woke at 5am. That’s 2am in our reeling California minds. The news reported that the countdown was running smoothly.
As we headed to the accreditation office for our media badges, we saw pockets along the coast filled with RVs, cars, and tents. The news reported that 750,000 people are expected to view the launch in person here. They recommended that people driving in from Orlando (a 25-minute drive for us last night) leave by 8am to arrive in time for the 3:47pm launch. Who knows when we’ll be able to get back to the motel, if the launch goes off as planned?
Meanwhile, we secured a shared spot in the Annex at the KSC Press Center, and we’re parked in an extra lot. The main building’s desk spots are full, and the Annex is nearly so, though reporters are only now trickling in. We’re on a standby list for the astronaut walkout, the seats on the bus having been filled yesterday. We have a few one-on-one interviews set for this afternoon.
Nuclear Secrecy April 27, 2011Posted by Lofty Ambitions in Science.
Tags: Books, Nobel Prize, Nuclear Weapons, Physics, Radioactivity
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At the end of March, an interesting article appeared on CNN.com in the TECH section. Entitled “Former truck driver deciphers top secrets of first atomic bombs,” the article detailed the efforts of John Coster-Mullen to understand the physical aspects of Fat Man and Little Boy, the weapons that gave rise to the atomic age and the Cold War. Coster-Mullen’s book Atom Bombs: The Top Secret Inside Story of Little Boy and Fat Man, of which we have a copy, is an exacting, detail-driven exploration of the construction of those two weapons (and the dozens of test and engineering articles that were also constructed).
Coster-Mullen’s book has much in common with Chuck Hansen’s U.S. Nuclear Weapons: The Secret History, in that they were both created through extensive research, exhaustive Freedom Of Information Act (FOIA) requests, and obsessive mindsets. A detailed discussion of the two texts is something that we’ll probably do in the future, but for this post, we’d like to address two of the misunderstandings that are created by the CNN article’s title and the follow-on, user-generated commentary.
Every time a book (or even an article about the book) like Coster-Mullen’s comes along, there is an outcry that the author shouldn’t be making so-called secrets about nuclear weapons public. Really, though, there has never been any such thing as an atomic secret, at least not one that could be kept secret for very long. Despite the uninformed blathering of our elected class that took place during the Cold War, it was clear by 1945 to most of the Manhattan Project scientists that it was only a matter of time until other nations had learned the secrets of manufacturing nuclear weapons. As was said at the time, “No nation has a monopoly on the laws of nature.”
This acknowledged fact led to vigorous debate among top Los Alamos scientists about the advisability of simply making the designs for Little Boy and Fat Man open secrets, not really secret at all. The history and background on this debate is covered exhaustively in the Trinity chapter and Epilogue of Richard Rhodes’s The Making of the Atomic Bomb. The leading proponents for this open dissemination of the bomb designs were Nobel Prize winners Niels Bohr (known as not-so-tricky Nicholas Baker when extra security was employed) and Leo Szilard, holder of the patent for sustain chain reaction.
Even though the Manhattan Project designs were never released into the open scientific literature, a staggering amount of information about the design and implementation of nuclear weapons was publically available in scientific journals throughout the Cold War. Any sufficiently motivated group of scientists and engineers would have been able to build their own nuclear weapon, probably from the moment that the designs for the Manhattan Project weapons were finalized.
The clearest test of this thesis came about as a byproduct of the so-called “Nth Country Experiment,” which was run by the Atomic Energy Commission and Lawrence Livermore Laboratory in the 1960s. Predicated on the fact that the United States was the first country to develop nuclear weapons, Russia was the second, and so on, the experiment asked: What resources would it take for a small, presumably hostile (or at least moderately belligerent) nation to become the Nth-country?
The program took three recent physics Ph.D.s who had no prior exposure to nuclear weapons development, provided them with access to open literature and computational resources, and tasked them with developing a nuclear weapon. The young physicists took up the challenge of designing the more difficult Fat Man or implosion-type weapon. Their design was completed in two-and-a-half years—even though they weren’t working on this project full time—and adjudged by weapons experts to have a fair probability of having produced a plausible, working weapon.
Then, as now, the only technical activities that stand in the way of the production of nuclear weapons is obtaining and enriching the fissile materials: uranium and plutonium. That’s what we hear about in the news—acquisition and enrichment—because the secret was out before it could be kept.
The Anniversary of Chernobyl April 26, 2011Posted by Lofty Ambitions in Science.
Tags: Museums & Archives, Radioactivity
Today marks the twenty-fifth anniversary of the accident at the Chernobyl nuclear power plant in Pripyat, a small town in what was then the U.S.S.R. (For information about the National Chernobyl Museum in Kiev, click HERE.) Less than a month ago we commemorated the less worrying Three Mile Island accident. The anniversary of Chernobyl has an unfortunately heightened significance this year because another nuclear catastrophe occurred just weeks ago, on March 11, at the Fukushima Daiichi nuclear power plant in Japan.
That accident in Japan is ongoing. The International Atomic Energy Agency’s update today begins, “Overall, the situation at the Fukushima Daiichi nuclear power plant remains very serious, but there are signs of recovery in some functions, such as electrical power and instrumentation.” The evacuation zones have been expanded, and white smoke is still billowing from Units 2, 3, and 4. Yesterday, TEPCO, the Tokyo Electric Power Company, reported that there are 70,000 tonnes of highly radioactive water in the basements under Units 1,2, and 3. The levels of radioactivity being detected in the surrounding areas and in the food are falling, and some restrictions on the distribution of milk and vegetables have been lifted. As bad as the accident in Japan is, and even though it is rated a 7 (the worst on the INES scale), it doesn’t seem nearly as bad as Chernobyl was—and continues to be.
Several days ago, NPR ran a story on All Things Considered that featured journalist Svetlana Alexievich’s oral history project Voices of Chernobyl, which she collected in the 1990s and which was translated into English in 2005. The book’s historical notes remind readers of the scope of the catastrophe and its lack of resolution. One reads, “As a result of Chernobyl, the country lost 485 villages and settlements. Of these, 70 have been buried underground.” Another reads, “The fourth reactor, now known as the Cover, still holds about twenty tons of nuclear fuel in its lead-and metal core. No one knows what is happening with it.”
The rest of Voices of Chernobyl is much more difficult to read. The Prologue is the voice of Lyudmilla Ignatenko, the wife of a firefighter. Her husband rushed to the initial scene in his shirt sleeves. He died in a hospital in Moscow within a couple of weeks, as did the other first responders. Though the doctors forbade it, she hugged and kissed her radioactive husband. When she gave birth to her daughter a few months later, the baby died within a few hours of liver cirrhosis and heart disease.
In Lyudmilla Ignatenko’s own words: “While I was there with him, they wouldn’t, but when I left—they photographed him. Without any clothes. Naked. One thin sheet on top of him. I changed that little sheet every day, and every day by evening it was covered in blood. I pick him up, and there are pieces of his skin on my hand, they stick to my hands. […] Any little wrinkle [in the sheet], that was already a wound on him. I clipped my nails down till they bled so I wouldn’t accidentally cut him. None of the nurses could approach him; if they needed anything they’d call me.”
In the words of Nadezhda Vygovskaya, an evacuee: “At eight in the morning there were already military people on the streets in gas masks. When we saw them on the streets, with all the military vehicles, we didn’t grow frightened—on the contrary, it calmed us. The army is here, everything will be fine. We didn’t understand then that the ‘peaceful atom’ could kill, that man is helpless before the laws of physics.”
In the words of Ivan Zhykhov, a chemical engineer: “What’s radiation? No one’s heard of it. Whereas I’ve just gone through a civil defense course where they gave us information from thirty years before, like that 50 roentgen is a fatal dose. They taught us to sit down so the wave of the explosion would miss us. They taught us about irradiation, thermal heat. But about the radioactive contamination of an area—the most dangerous factor of all—not a word.”
Zhykhov goes on: “In the middle of our time there they finally gave us dosimeters. These little boxes, with a crystal inside. Some of the guys started figuring, they should take them over to the burial site in the morning and let them catch radiation all day, that way they’ll get released sooner. Or maybe they’ll pay them more. So you had guys attaching them to their boots, there was a loop there, so that they’d be closer to the ground. It was theater of the absurd. […T]hese were little toys they’d picked out of their warehouse from fifty years ago. It was just psychotherapy for us. At the end of our time there we all got the same thing written into our medical cards: they multiplied the average radiation by the number of days we were there. And they got that initial average from our tents, not from where we worked.”
By the end of 1986, Chernobyl had been sealed with a concrete sarcophagus, and most of us thought that concluded the event. Of course, that’s not the case. The hope is that the Chernobyl nuclear power plant will be fully decommissioned by 2013. In the meantime, as Svetlana Alexievich points out in her afterword, “Thousands of Russian refugees from Armenia, Georgia, Abkhazia, Tajikistan, Chechnya—from anywhere where there’s shooting, they come to this abandoned land and the abandoned houses that weren’t destroyed and buried by special squadrons. […] All the talk about how the land, the water, the air can kill them sounds like a fairy tale to them. They have their own tale, which is a very old one, and they believe in it—it’s about how people kill each other with guns.”
In Japan, TEPCO has recently drawn up plans to do a cold shutdown within nine months and decommission Fukushima Daiichi within ten years, plans that strike some as overly optimistic.
Look for our post tomorrow for more in our series about radioactivity and things nuclear.
A Launch to Remember (Part 2) April 25, 2011Posted by Lofty Ambitions in Science, Space Exploration.
Tags: A Launch to Remember, Apollo, Space Shuttle
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Our first post in this series, “A Launch to Remember,” was on Friday, April 22. Scroll down, or click HERE to read from the beginning.
For the past two years, a part of what we’ve been up to in our day jobs is building a collection of NASA related materials at the Leatherby Libraries. NASA has been divesting itself of an extraordinary range of its material culture through the GSAXcess website. When we first started requesting items in the fall of 2009, artifacts from the earliest NASA human-rated programs, Mercury and Gemini, were still available. There were also items such as crew clothing from Apollo.
So why aren’t we sporting Michael Collins’s spare spacesuit? The request process is set up so that government affiliated institutions, such as the National Air and Space Museum, get first pick. In the end, we didn’t get any Apollo-era goodies, but it was a beautiful dream while it lasted.
That said, we didn’t come up empty handed. In fact, we have received a number of items, and we are expecting more as the space shuttle program heads off into the sunset (or moonrise). On December 1, 2010, NASA announced an adjunct to the larger artifacts program in the form of a giveaway of space shuttle tiles. As a qualifying entity (a university library in this case), we immediately dashed off our request. Our piece of tile arrived just over three months later.
Pulling the bubble-wrapped packaging out of the shipping box revealed a black-and-white block roughly five inches by five inches and about two inches thick. The tile was shrink-wrapped itself, and the lone documentation in the box, attesting to the tile’s authenticity, cautions against removing the wrapping. In a bit of irony to which we’ve grown accustomed recently, the document indicates that the “silica material in Shuttle tiles is not classified as hazardous. However, material from the silica fiber layer can cause temporary irritation of the throat and/or itching of the eyes and skin. Touching a bare tile should be avoided.” (The emphasis is all NASA’s.) That’s the old government lawyerese two-step: this isn’t dangerous when it’s doing what it’s designed for (i.e., protecting the space shuttle from the searing heat of reentry), but if you touch it, you might regret it.
The first thing that everyone notices when handling the tile is just how ridiculously light it is. This leads a lot of people to speculate that the white underside is made of polystyrene, which goes by a common brand name. In reality, the silica material is lighter than polystyrene by virtue of the fact that it is 94% air by volume. (For more on the Orbiter Thermal Protection System, including the LI-900 silica, click HERE.) The tile’s black and white coloration makes it seem as if the block has two halves. In fact, it is all one piece of silica, and the black part is a glass coating added to the tile to both waterproof it and enhance its heat sink properties.
The next thing that people notice is the sequence of numbers that has been painted onto the tile. In the case of our piece of the tile, the number is V070-396050 -020 -008043. The number can be used to recreate an identical tile if necessary, and it also serves as a bit of metadata about the tile, giving information such as: 1) the kind of tile type, of which there are at least four—HRSI, FRCI, TUFI, and LRSI; 2) the shuttle orbiter; and 3) the installation location on the orbiter. A kind friend of the Leatherby Libraries was able to use our tile’s identification number to track down its history. Our tile is of the 9lb high-temperature reusable surface insulation (HRSI) type. The 9lb designation means that the material weighs nine pounds per cubic foot. The tile was originally installed on the left, Orbital Maneuvering System pod. These are the two humps that you see at the base of the shuttle’s horizontal stabilizer. The OMS pods can be removed from the shuttle orbiter, and they are, to some degree, interchangeable (excepting the right/left symmetry). Our tile was originally attached to pod #021. Our tile never flew; for some reason it was removed and replaced on July 14, 1982. This particular pod, OMS021, was initially attached to either Challenger or Columbia, but our reliable friend was unable to verify this piece of information precisely.
As we consider our trip to Cape Canaveral later this week, holding this tile in our hands reminds us that each shuttle is made of myriad upon myriad little pieces, all fit together in a particular way. Likewise, each of the machines pieces represents the work of many individuals, all working individually and in sync to make the penultimate space shuttle mission go smoothly.
A Launch To Remember (Part 1) April 22, 2011Posted by Lofty Ambitions in Collaboration, Space Exploration.
Tags: A Launch to Remember, Countdown to the Cape, Radioactivity, Space Shuttle
In a stroke of luck emerging out of hard work, we have been granted press credentials to attend next week’s scheduled launch of space shuttle Endeavour. Both of us! In the press stands! As close as the public can get!
Doug got the approval from NASA earlier this week. Elation, from the Latin meaning to bring out of, as in Doug was brought out of a funk. Elation, meaning joyfulness or exaltation of spirit as a result of success or relief. As much as he had looked forward to walking the four miles from the motel to the coast, then holding his viewing spot for hours among throngs of people, Doug is now looking forward to being right there with the rest of the press corps.
Shortly after the news that Doug was approved for media credentials for the impending mission, the White House announced that the Obama family plans to join Lofty Ambitions to view the launch. Representative Gabrielle Giffords, the wife of STS-134 commander Mark Kelly, plans to be there too. (We’ve written before about Kelly and Giffords, who is recovering from a gunshot wound, and about astronauts Mark and Scott Kelly. Click HERE to read Obama’s write-up of Giffords as one of Time’s 100 most influential people.) Okay, the press viewing area is separated from the bleachers designated for officials and astronauts’ families—a move made after the Challenger accident—but not by very much. It’s easy waving distance. Kennedy Space Center employees get a little closer to launch pad 39A.
Doug will be covering the event for Knox Magazine, the publication of our alma mater and of Barack Obama’s, if you count honorary degrees. Anna will be covering, once again, the end of the space shuttle program for Chapman Magazine. Our article on November’s not-launch of Discovery is in press right now with that publication. Of course, our series about that trip—“Countdown to the Cape” (October 27 through November 7)—is available right here at Lofty Ambitions, too.
We wish we could go a couple of days before launch for all the press events, but Anna teaches on Wednesday night, so we’ll swoop in the night before the launch. (Don’t worry, we already arranged to have someone watch our humble abode while we’re away.) We’ll miss the rollback of the Rotating Service Structure, but we have close-ups of that from Discovery. If the launch doesn’t face delay, tanking will begin at 6:22a.m. Friday, April 29, just after the crew wakes up. We’ll already be awake and heading toward the press site.
The launch is scheduled for 3:47p.m. that day, and we should have several posts to share! In the coming few weeks, we’ll also continue our series on Fukushima Daiichi and how we talk about radioactivity (March 16 through April 20 thus far). But check back on Monday for Part 2 in this new series that starts today: “A Launch to Remember.”
Radioactivity Units of Measurement April 20, 2011Posted by Lofty Ambitions in Science.
Tags: Nobel Prize, Physics, Radioactivity
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Recently, the ongoing nuclear disaster that is Fukushima Daiichi Nuclear Power Station was given the ultimate designation on the International Nuclear and Radiological Event Scale (INES), a 7. Many media outlets covered the rationale behind the reclassification, including an article from the New York Times. The IAEA also has a pamphlet online that explains the various designations.
What’s common to both the NYT article and the IAEA pamphlet is the use of terminology—in the form of units—that attempts to quantify some aspect of measuring radioactivity. Most of the articles that discuss the upgrading (the use of the word upgrade here is unfortunate, as if the Japanese people have somehow had their lot improved) of the Fukushima Daiichi disaster to a level 7 also mention that at least some part of the rationale for the higher designation is the amount of radioactive materials that have been released into the environment. Most articles cite a report from the Nuclear Safety Commission that puts the total amount of released radioactive materials at 630,000 terabecquerels (TBq). (By comparison, the Chernobyl disaster is estimated to have had a total release of 5.2 million TBq.) The INES pamphlet also makes use of radiation measurement units. For example, in a level 2 incident, members of the public would have to receive dosages of greater that 10 millisieverts (mSv).
Articles about the Fukushima Daiichi accident have contained a bewildering array of terms that are used in measuring radiation: curies, rads, rems, becquerels, and sieverts are among those that we recall reading over the last month. A couple of others used for measuring radiation, but that we haven’t seen mentioned, are grays and roentgens.
One of the reasons for the multiplicity of the radiation measurement units is the dilemma that we have faced in the United States for far too long now, the use of U.S. common units versus SI units (SI stands for the International System). The other reason for the wide array of units is vastly more interesting: there exist a range of types of radiation measurements that one might want to take. For the purposes of this post, we’re going to address four types of radiation measurements and their respective units: 1) Activity, 2) Exposure, 3) Absorbed dose, and 4) Equivalent dose.
Measuring activity is effectively asking the question, “How much?” In other words, one type of measurement assesses how much radioactivity has been released into the environment. As was mentioned earlier, in the case of Fukushima Daiichi, the answer to that question is 630,000 TBq. The becquerel is an SI unit that that corresponds to a single radioactive decay (or disintegration) event per second. The U.S. unit that describes activity is the curie (named for Pierre and Marie Curie, about whom we’ve written before), and it’s tied to the radioactive decay processes of a sample of radium (an element the Curies discovered). So, one curie is equal to the amount of radioactive decay that take place in radium in one second. In mathematical terms, that’s 3.7 x 10 to the 10th decays (37,000,000,000, if you’re keeping score at home). The conversion relation for curies and becquerels is an relatively straightforward: 1 curie = 3.7e+10 becquerels. The important think to keep in mind is that both curies and becquerels are measurements of activity.
The next radiation measurement worth exploring is exposure. Although you might naturally assume that exposure would imply a human or some other tangible target, that wouldn’t be exactly right. (In fact, that’s closer to dosage, which we discuss below.) Instead, radiation exposure measures the ionization of a mass of dry air, whether or not any person is exposed to it. In fact, using the term exposure has an even more constrained meaning in that it is only applicable to energy deposited in the air by gamma and x-rays (not, say, for beta decay). (See more about radiation terms HERE.) The U.S. unit for measure exposure is the roentgen, and the SI equivalent is coulombs/kilogram. But there are better measures than exposure for describing the biological dangers that one might face by coming into contact with radioactivity.
Dosages come in several flavors; two of the most common are absorbed dose and equivalent dose. Each of these dosage measures attempts to quantify the biological impact of coming into contact with radioactive materials. The first measure—absorbed dose—addresses the effects of the energy that is deposited—or absorbed—as ionizing radiation interacts with the body. The U.S. unit for this measurement is the rad, which is an acronym for radiation absorbed dose. The SI unit for absorbed dosage, and one that we haven’t yet seen in the press, is the gray (gy). One gray is equivalent to 100 rads.
The final dose measurement of particular interest to us right now is the radiation measure that we have encountered most frequently in the media: equivalent dose. The equivalent dose differs from the absorbed dose in that it accounts for differing types of radioactivity. Different types of radiation—alpha-, beta-, gamma-, x-rays—interact with matter in distinctive and unequal ways. The equivalent dose introduces a quality factor to address the discrete biological damage regimes of each type of radioactivity. The U.S. unit for equivalent dose is the rem. Again, this is an acronym; it stands for roentgen equivalent man—or roentgen equivalent in man, meaning mammal. To come up with a measurement in rems, it is necessary to multiply rads by the quality factor for the specific radiation type. The SI unit of equivalent dose is the sievert (sv). It can be exchanged with rems in the same way that rads and grays are converted: a single sievert is equivalent to 100 rems. In other words, equivalent dose—as expressed in rads or sieverts—is really important because it’s a way to weight absorbed dosage in a way that better reflects what radioactivity means to the human beings who come in contact with it.
(For a big conversion chart of these and other measurements for radiation, click HERE.)
The INES grades radiological events as either incidents (levels 1-3) or accidents (levels 4-7). No number on this scale is exactly equivalent to any of the four ways of measuring radioactivity, and other factors, in addition to radioactivity levels, are considered when assessing the extent of a radiological event. We’d like to suggest another term for the worst nuclear accidents: cataclysm. Thankfully, there have been only two level-7 accidents; Chernobyl and Fukushima Daiichi clearly meet the intended definition of cataclysm, a word whose etymology comes from the Greek kataklysmós, meaning flood deluge. In the case of these two events, it hasn’t been torrents of water that have changed the earth’s surface, rendering the area uninhabitable. Instead, showers of radioactive isotopes—such as the cesium, iodine, and strontium we discussed last week—have turned the areas around Chernobyl and Fukushima Daiichi into a wasteland.
Guest Blog: Ken Kremer April 18, 2011Posted by Lofty Ambitions in Guest Blogs, Science, Space Exploration.
Tags: Art & Science, Biology, Mars
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Today, we feature a guest blogger who will catch us up with two of the space program’s greatest accomplishments, the Mars rovers. Anna met Ken Kremer as part of the press core for STS-133 back in November and was especially impressed by his range of knowledge about NASA and his enthusiasm.
Ken Kremer is a freelance science writer and scientist who regularly publishes writing and photography in online and print venues, including New Scientist, Science News, Aviation Week, and Spaceflight Now. For more of Ken Kremer’s work at Universe Today, click HERE. He does lectures around the country at museums, universities and schools, and clubs. He’s served as a Solar System Ambassador since 2005.
Photo credit for the three panoramic photographs here: NASA/JPL/Cornell, Marco Di Lorenzo, Kenneth Kremer.
MARS ROVERS CELEBRATE SEVENTH ANNIVERSARY ON RED PLANET
NASA’s twin Mars rovers Spirit and Opportunity surely rank as one of the greatest triumphs in the history of space exploration.
Seven years ago, the dynamic duo landed on opposite sides of the Red planet on January 3 and January 24, 2004. They were originally designed to operate for just 90 Martian days, or sols, with an outside possibility they might last a few months longer. In actuality—during the extended mission phase—they have endured light years beyond the mere three-month warranty proclaimed by NASA as the mission began with high hopes following the nail-biting so-called six minutes of terror as the twins plunged through the Martian atmosphere with no certainty as to the outcome of the landing.
Since 2004, the rovers’ longevity has far exceeded all expectations, and no one on the science and engineering teams that built and operate the twins can believe they lasted so long and produced so much.
Spirit and Opportunity have accomplished a remarkable series of scientific breakthroughs, far surpassing the wildest dreams of all the researchers and NASA officials. Indeed, both rovers are positioned at scientific goldmines on the red planet’s surface. Opportunity is still alive and trekking across the Martian plains, now 84 months into the three-month mission. By the time of her last dispatch from Gusev crater, Spirit had lasted for nearly six years of bonus mission time.
New images taken by the rovers appear at NASA’s Mars Rover websites on a continuing basis. The raw images have inspired myself and others to assemble panoramic mosaics from the individual snapshots to illustrate the broader context of what Spirit and Opportunity see. This blog post includes a few photomosaics created by Marco Di Lorenzo and myself to show the current environments explored by both rovers.
Spirit last communicated with mission controllers back on Earth on March 22, 2010. The rover had entered hibernation mode as the autumn sunlight available to power her life giving solar arrays was diminishing. NASA hopes to reawaken Spirit from a long slumber and reignite her illustrious campaign of exploration and discovery. No one is giving up hope for Spirit, and NASA is stepping up operational efforts to contact the plucky rover since the amount of springtime Martian sunlight is now increasing over the next few months.
Although Spirit has been stalled at a place called Troy since April 2009, the rover made a significant science discovery at that exact spot. Spirit examined the soil in great detail and found key evidence that water, perhaps as snow melt, trickled into the subsurface fairly recently and on a continuing basis. While driving on the western edge of an eroded over volcanic feature named Home Plate, Spirit unknowingly broke through a hard surface crust (perhaps 1 cm thick) and sank into hidden soft sand beneath. At Troy, the rover discovered that the crust was comprised of water related sulfate materials and therefore found further evidence for the past flow of liquid water on the surface of Mars – a great science discovery! Our photomosaic shows the very last panoramic view taken by Spirit at Troy.
Meanwhile, Opportunity is blazing a trail of discovery in the Meridiani Planum region of Mars. This rover completed exploration of the stadium-sized Santa Maria Crater which holds deposits of water bearing minerals that will further elucidate the potential for habitability on the red planet. The rover arrived at the western edge of the relatively fresh impact crater on December 16, 2010 (Sol 2451). This intermediate stop on the rover’s 19-kilometer journey from Victoria Crater to giant 14-kilometer-wide Endeavour Crater provides important ground truth observations to compare with the orbital detection of exposures of hydrated sulfate minerals.
Opportunity is driving to different vantage points around the steep walled crater and snapping a series of gorgeous Martian vistas. The rock-strewn crater is a Martian geologist’s dream. As our photomosaics show, the robot was imaged on New Year’s Eve in exquisite high resolution from Mars orbit while parked at the sharp edge as she was simultaneously snapping a multitude of awesome views peering inside the stunning and scientifically interesting crater.
Santa Maria is just six kilomters from the western rim of Endeavour which shows spectral signatures of phyllosilicates, or clay bearing minerals, which formed in water about four billion years ago and have never before been directly analyzed on the Martian surface. Phyllosilicates form in neutral aqueous conditions that could have been more habitable and conducive to the formation of life than the later Martian episodes of more harshly acidic conditions in which the sulfates formed that Opportunity has already been exploring during her seven-year overland expedition. See the Astronomy Picture of the Day featuring Opportunity HERE.
Opportunity remains healthy and has abundant solar power for the final leg of the long eastward march to Endeavour, with arrival later in 2011. See the rover’s progress HERE. And click HERE for Google Mars.