British billionaire Richard Branson says he's sending over a medical officer to talk with physicist Stephen Hawking about getting him into space. That's how the founder of Virgin Galactic responded to Hawking's comment that "maybe Richard Branson will help" him achieve his long-held goal of reaching the final frontier, even though he's a quadriplegic who needs a blink-controlled computer to communicate.

Getty Images file

Stephen Hawking is arguably the world's best- known living physicist.

Branson and other Virgin executives indicated today that if there's any way on earth to accommodate the good doctor-with-a-disability, they'll do it. And for practice, Hawking could conceivably experience weightlessness aboard a Zero Gravity Corp. plane as early as next year.

It would be one giant leap for the world's best-known physicist - and a powerful signal of support for other people with disabilities.

Hawking, who has been coping with a degenerative nerve disease for decades and now spends most of his waking hours in a high-tech wheelchair, is famous for his theoretical work on black holes and other space curiosities. He's also a major-league space geek, going so far as to play a virtual version of himself on "Star Trek: The Next Generation." For months he's been dropping hints about going beyond mere theorizing and play acting, by flying to the edge of space on one of Branson's yet-to-be-built suborbital spaceships.

Today's public reference to Branson was the most explicit hint to date, and the rebel billionaire responded in a statement e-mailed by his office:

"Obviously we would be honoured to have Stephen fly with Virgin Galactic. We have a great medical team and we are planning to have our Chief Medical Officer sit down with Stephen, and we will do everything in our power to make his dream of going to space possible. But at the end of the day, it will be Stephen's decision, and it goes without saying we would be delighted to have him onboard."

Virgin Galactic is targeting the start of its $200,000-per-seat service for late 2008 or 2009, so there's plenty of time to make the arrangements. The company's head of astronaut relations, Stephen Attenborough, told me that Virgin has been in touch with Hawking in the past and will be following through on today's exchange.

"We're going to be making contact with Stephen in the next few days," Attenborough said.

For some time, Virgin Galactic has been working through the issues that need to be addressed in order to accommodate people with disabilities on suborbital spaceflights, Attenborough said. Because current regulations call for suborbital passengers to fly at their own risk, "there's probably no regulatory reason we couldn't fly anyone, with informed consent," he said. However, Virgin wants to make sure that its spaceflights are as safe as possible - a stance laid out in this passage from the recently published book "Kids to Space":

Q: What are Virgin Galactic's plans for taking disabled people to space?

A: According to Virgin Galactic, "We absolutely want and expect to be able to take disabled people to space. We do not need people to be super-fit, and there will be many physical conditions that will be no issue whatsoever. Unlike manned space travel to date, we will be looking to screen people in, not screen people out. However, it is incredibly important for the future of the industry that we fly people safely, so there will be restrictions that center around heart and circulatory conditions, and anything that prevents people from complying with emergency procedures … particularly being able to exit the vehicle quickly."

That last concern would be the key sticking point for Hawking's flight - and would no doubt be a subject for discussion with Virgin Galactic's medical team. One way to address that concern would be for an assistant or two to accompany him on the spaceflight. The assistants could place the physicist in his seat, ride along with him to the peak altitude in excess of 62 miles (more than 100 kilometers), guide him through the weightless portion of the flight, then settle him back in the seat for the landing.

All this assumes that Hawking could withstand the G-forces associated with the trip. Again, that's something for the medical team to judge. But if all the arrangements work out, Attenborough said having Hawking aboard SpaceShipTwo would recognize the physicist's "unique contribution" to science - and serve as a "really great demonstration" that disabilities needn't stand in the way of outer-space dreams.

"One of the key objectives has always been to make space as inclusive as possible. ... If there's one person we would love to realize the dream for, it would be Stephen," Attenborough said.

Noah McMahon, chief marketing officer for Zero Gravity Corp., said experiencing weightlessness could be a particularly liberating experience for people with disabilities. "If you're bound to a wheelchair, there's nothing more exciting than being able to float free," McMahon told me.

Zero Gravity gives customers that weightless feeling over and over again, for about a half-minute at a time, on planes that fly a series of special parabolic maneuvers. The package costs $3,750 per seat.

McMahon said Zero Gravity has already flown several of the disabled, including a blind person, and is finishing up work with the Federal Aviation Administration on procedures for accommodating paraplegics and quadriplegics. "We've just gone through all the steps we had to go through in order to make that happen," McMahon said.

Again, the main concern would be moving wheelchair-using fliers between their seats and the open space used for floating. Such fliers would be required to have one or two assistants, depending on their mobility, McMahon said.

McMahon said he expects that Hawking as well as other wheelchair users would be welcome to come aboard starting early next year.

"It's good timing," McMahon told me.

• Wired.com visits subatomic inferno (and physicists' paradise)
• Scientific American: 20 gadgets we love 
• LiveScience: Scientists say dino die-off took just one asteroid 
• Science @ NASA: A new paradigm for lunar orbits

The real-life spy thriller surrounding the poisoning of Russian defector Alexander Litvinenko makes the apparent poison, radioactive polonium-210, sound like a supersecret killer ingredient. It's rare to find it in lethal concentrations, to be sure - but actually not so rare to find it in everyday life.

In minute quantities, polonium-210 has been used over the years to spark up spark plugs and banish static cling. Polonium is one of the carcinogens in tobacco smoke, and you can buy a smidgen of it over the Internet at $69 a pop, as more than one news report has noted. Heck, there's even radioactive polonium in plain old dirt.

"It's present in all of us, in trace amounts - say, in nanocuries," said Keith Eckerman, a senior research scientist at Oak Ridge National Laboratory.

The amount is key. We might notice no ill results from billionths of a curie (which serves as a measure of activity). In contrast, Litvinenko is thought to have been exposed to something around 5 millicuries (thousandths of a curie), said Kelly Classic, associate editor for media relations at the Health Physics Society.

That's a minute amount - a speck of polonium that active would weigh less than a millionth of a gram, according to the Health Physics Society's information sheet on polonium (PDF file). But getting that much polonium together would probably require going to the source, which usually involves a nuclear reactor. This is why investigators are thinking the hit on Litvinenko was a high-level spy-vs.-spy job.

The amounts used in industrial applications - yes, including those $69 polonium samples, which are typically used to calibrate radiation detection devices - are far more minute: a speck of a speck of a speck.

Polonium is notable among radioactive substances because its radioactivity comes exclusively in the form of alpha particles - positively charged clumps comprising two protons and two neutrons. Such radiation poses a negligible external hazard, because it penetrates only a few cells deep. That's why it's useful for calibrating radiation detectors, Eckerman said.

But if enough polonium-210 is ingested or breathed in, it causes big trouble - as the death of Alexander Litvinenko has demonstrated. Within days, the spy-turned-whistleblower succumbed to radiation poisoning.

So should the authorities shut down the $69 polonium operation? Hardly.

The radioactive samples that United Nuclear is selling over its Web site are encased in disks of inert material, or planchettes, as a safety measure, and thus aren't considered all that hazardous, Eckerman told me. "It's physically bound to that substrate, so it's not possible to mechanically remove it," he said. "You'd have to dissolve the whole planchette."

United Nuclear does have an extra measure of intrigue because it was founded by Bob Lazar, who has claimed that he helped the U.S. government reverse-engineer alien UFO technology. But even if Lazar is a "UFO nut," there doesn't seem to be much mystery surrounding United Nuclear's scientific supply operation.

Polonium-210 also is contained within protective sheathing in the modern-day materials and devices used to cancel out static electricity - which would again make it difficult to turn the tiny radioactive mini-specks into something dangerous. "You would have to break the device open and scrape off the polonium," Classic told me.

Even if you could somehow isolate the polonium from hundreds of $69 disks, or thousands of static-neutralizing brushes, you wouldn't have nearly enough to create the Litvinenko effect. Theoretically, the best you might be able to do is elevate a person's cancer risk, years down the line.

The fact that polonium-210 isn't as well-known as plutonium or uranium is probably a big factor behind the interest in an incident that is sounding more and more like a "science-fiction spy thriller," Classic said.

"They happen to be using something that most of the population hasn't heard about before," she observed, "which makes it even more mysterious."

• National Geographic: Saturn the beautiful stranger
• Nature: Does everyone smell different?
• Champagne cork injuries and other lowlights from Mini-AIR
• The Onion: Kansas outlaws practice of evolution

Blue Origin, the secretive rocket venture backed by Amazon.com billionaire Jeff Bezos, has set aside time between this Thursday and Dec. 2 for another test launch from its ranchland spaceport in West Texas. The first test was conducted earlier this month, with Blue Origin calling it a success.

Word of the second scheduled launch opportunity comes in a notice to airmen issued by the Federal Aviation Administration, and picked up by the brand-new blog Futuresheet (thanks, John!). The required issuance of a notice to airmen is how we found out about the first test launch as well.

The latest notice sets up flight restrictions near Blue Origin's launch site, extending out in a 5-nautical-mile radius and up to an altitude of 10,000 feet, between 7:30 a.m. CT Thursday and 12:30 p.m. CT Dec. 2. The flight profile for these initial tests calls for an unmanned, rocket-powered prototype to lift off vertically, take a controlled flight to an altitude of a few hundred feet or even more, then come back down.

Over the next four years, the test flights would become increasingly ambitious, climaxing in passenger flights that would rise to altitudes in excess of 62 miles (100 kilometers). At that height, riders would feel a few minutes of weightlessness and see the curving Earth beneath the black sky of space. Technically speaking, they would be space travelers (although it might be too much of a stretch to call them astronauts).

Blue Origin was tight-lipped about the first test, although the venture's project manager did tell the Van Horn Advocate that the outcome was successful. That might be as much as we'll hear going forward.

"Blue Origin does not plan to comment on its ongoing test program and won't be releasing information on the individual tests scheduled," a spokesman for the venture, Bruce Hicks, told me today in an e-mail.

So if you're near Van Horn, Texas, and are disposed to keep an eye out for some rocket action, keep me posted on what you see over the next few days. But don't forget the binoculars: The launch pad is on Bezos' ranch, set off quite a ways from Highway 54. Daniel Schmelzer's Carried Away travelogue provides several pictures that will help you get situated.

• New Scientist: Europe joins hunt for missing Mars probe
• Aviation Week: White Knight flies on to new missions
• Defense Tech: The 'Deadlies' ... awards for the world's worst weapons
• N.Y. Times: A different kind of string theory

Two groups of European researchers are going ga-ga over gamma-ray blasts from different sources, both thought to be black holes acting up.

One gamma-ray source, known as IGR J717497-2821 (let's call it IGR for short), appears to be a newborn black hole. The other, LS 5039, is an unusual high-energy modulator that researchers call the first-ever "gamma-ray clock."

ESA

In this animated before-and-after image from Integral, the arrow indicates the gamma-ray source known as IGR J717497-2821. The other variable sources are well-known X-ray binaries.

IGR was spotted by the European Space Agency's Integral gamma-ray space observatory on Sept. 17, during a survey focusing on the center of our own Milky Way galaxy. "The galactic center is one of the most exciting regions for gamma-ray astronomy, because there are so many potential gamma-ray sources," Roland Walter, an astronomer at the Swiss-based Integral Science Data Center, explained in today's ESA advisory.

Once the Integral team spotted the blast, other astronomers around the world were alerted to watch the phenomenon as well. Ground-based telescopes as well as the ESA's XMM-Newton X-ray observatory, NASA's Chandra X-Ray Observatory and the Swift gamma-ray space telescope gathered more data about the flash, which became brighter for a few days, then faded away over a matter of weeks.

The rise and fall of gamma-ray emissions followed the pattern that astronomers associate with a double-star system - in which one of the stars is like our sun, and the other is actually a matter-sucking black hole. Such black holes result when a massive star collapses into a gravitational singularity so dense that not even light can escape from its grip.

In IGR's case, astronomers believe matter was pulled off the sunlike star to swirl into the black hole like water circling a bathtub drain. The swirling gas, known as an accretion disc, became unstable and collapsed into the black hole - sparking the outburst seen by Integral.

"Astronomers are still not sure why the accretion disc should collapse like this, but one thing is certain: When it does collapse, it releases thousands of times more energy than at other times," the ESA advisory observed.

Check out the Integral news release for still more information. A report on the nova is due to appear in the journal Astronomy and Astrophysics.

The same journal carries the report about LS 5039, from astronomers using the telescopes of the High-Energy Stereoscopic System in Namibia. LS 5039 was discovered last year by the HESS team, and found to be another type of double-star system.

One of the stars is known to be a hot blue star, 20 times as massive as our sun, and the other is presumed to be a black hole. The high-energy gamma-ray emissions from the system rise and fall in a complex cycle - apparently due to the way the stars orbit each other.

It takes four days to complete one orbit, and during that time the presumed black hole passes in front of the blue giant, then behind it. The gamma rays are strongest when the black hole is in front, and weakest when the blue star is in front.

Astronomers believe the ups and downs of the gamma-ray emissions have something to do with the interaction between the black hole and the blue giant's flux of subatomic particles. The weirder aspects of Albert Einstein's theories come into play, according to today's advisory from the HESS team:

"We know since Einstein derived his famous equation (E=mc²) that matter and energy are equivalent, and that pairs of particles and antiparticles can mutually annihilate to give light. Symmetrically, when very energetic gamma rays meet the light from a massive star, they can be converted into matter (an electron-positron pair in this case). So the light from the star resembles, for gamma rays, a fog which masks the source of the gamma rays when the compact object is behind the star, partially eclipsing the source."

The researchers say such interactions are what lead to the clocklike oscillations in the gamma rays, at cosmic energies 100,000 times higher than previously known. And the HESS team members say they'll keep their eyes on this clock for years to come.

"The way in which the gamma-ray signal varies makes LS 5039 a unique laboratory for studying particle acceleration near compact objects such as black holes," said the University of Durham's Paula Chadwick.

What part did Albert Einstein's first wife play in the origins of E=mc² and all that? First we had the allusion to the years-long debate over mathematician Mileva Maric's role ... then we had the argument against Maric's involvement from physicist/author Allen Esterson ... then we had the other side of the argument from Senta Troemel-Ploetz, speaking up for Maric ... and now we have a closing rebuttal from Esterson:

"I have only just seen Senta Troemel-Ploetz's response to my comments posted on Cosmic Log and my critique of her 1990 article, so my response is a little belated.

"Troemel-Ploetz writes that John Stachel is in a tradition that 'always attributes achievements to men even if the men themselves claim their wives were the authors.' She evidently knows nothing of Stachel's writings, which show that he is far from being the kind of person she characterizes in this way. His concern in relation to Mileva Maric is that 'exaggerated claims for her role on the basis of the present evidence can only do a disservice to her memory' ('Einstein from B to Z,' 2002, p. 37).

"In her comments Troemel-Ploetz fails to address what she is purportedly responding to and merely repeats arguments that have been rebutted by Stachel and me. Her omission of a crucial part of Stachel's argument makes her statement amount to a caricature of his position. On Cosmic Log I wrote: 'Leaving aside the work they did together on heat conduction, the topic they both chose for their diploma dissertations at Zurich Polytechnic, John Stachel has documented a score or more instances of Einstein's writing "I" or "my" in regard to the material in question. For instance, against the one occasion that Einstein wrote of "our work on relative motion" there are a dozen instances of his writing "I" or "my" in regard to the same subject matter - which, in any case, at that time involved classical Galilean relativity, not the groundbreaking special relativity principle he arrived at only in 1905.'

"Why does Troemel-Ploetz never mention the following sentences in Einstein's letters?

• "'I also wrote to Professor Wien in Aachen about my paper on the relative motion of the luminiferous ether against ponderable matter' (28 Sept 1899)
• "'I'm busily at work on an electrodynamics of moving bodies, which promises to be a capital piece of work' (17 Dec 1901)
• "'I spent all afternoon at [Professor] Kleiner's telling him my ideas about the electrodynamics of moving bodies.' (19 Dec 1901)

"Summarizing Stachel's full argument, whereas on the numerous occasions on which first-person singular pronouns are used in relation to this topic Einstein is alluding to specific ideas or work, the single use of 'our' in reference to 'relative motion' is unspecific (letter 27 March 1901). It occurs in a context in which he is seeking to reassure Maric about concerns she has that acquaintances might be saying 'bad' things about her, and reflects his desire at that time to draw his beloved in to his extra-curricular ideas that dominate his activities. Furthermore, in not one of her surviving letters does Maric respond with any mention of any extracurricular work or ideas of her own, nor in the two instances where we have her letters responding directly to Einstein's containing his ideas on physics does she so much as mention what he had communicated to her. On this issue it is important to examine all the evidence in its entirety, and draw conclusions on that basis, not simply select whatever items provide some support for one's position.

"Please note that Stachel and I are not downplaying Maric's role at that time as an eager and valued listener to his ideas, a companion when reading physics books he had sought out, and an occasional assistant in this process. But in the absence of a single document in which Maric mentions any ideas of her own on extracurricular topics, we don't believe there is any hard evidence that she made substantive contributions to his work, and certainly no evidence that she contributed to the celebrated papers of 1905.

"For a full response on this particular issue, see the comprehensive discussion in Stachel (1996, PDF file) and in my online article "Mileva Maric: Einstein's Wife."

"Troemel-Ploetz quotes Einstein: 'How happy I am to have found an equal in you (eine ebenbuertige Kreatur) who is as strong and independent as I am.' Does Troemel-Ploetz really think that a sentence like this in a letter by someone passionately in love with his beloved can be taken literally? (The 'strong and independent as I am' part was, unfortunately for Maric, not subsequently borne out, demonstrating that the sentence has no evidential value.) Einstein saw himself and Maric as nonconformists who rejected conventional views. Significantly, the two immediately preceding sentences refer to his pleasure at what he sees as their joint rejection of 'the philistine life,' so the context does not justify taking the sentiment in question to refer to academic ability.

"Troemel-Ploetz quotes Einstein: 'Until you are my dear little wife, we want to eagerly work together scientifically so that we won't become philistines...' In the overall context of the documentary evidence, with its complete lack of indications of independent ideas in physics by Maric, this is consistent with Einstein's fond hopes for their life together to be a joint pursuit of science rather than any reflection of actual joint achievements already attained. Furthermore, Troemel-Ploetz omits a single word at the end of the sentence that puts a slightly different complexion on it. Einstein finishes with '..., gellst' [as reproduced in Collected Papers, vol. 1, doc. 131]. This adds a note of tentativeness to the sentence [it roughly translates as 'right?' as given in the Collected Papers translation] missing in Troemel-Ploetz's version omitting that final word. She also fails to mention that in the immediately preceding letter Einstein writes, 'Soon you'll be my "student" again, like in Zurich,' which gives some indication of their actual roles when they were both at Zurich Polytechnic.

"Troemel-Ploetz writes: '[Maric] had the same training and more than Einstein.' Presumably she means by this that they both studied for a diploma for teaching mathematics and physics in secondary school. Many thousands of people of that age had the same 'training' as Einstein, but this says nothing of their capabilities or achievements. (What she means by 'and more' is anybody's guess - unless she is referring to the fact that Einstein was in the habit of skipping classes to follow up his ideas in physics.) One relevant fact that Troemel-Ploetz omits to mention is that, whereas Einstein was precociously gifted at mathematics, and later obtained grade 11 in the mathematics component of the final Diploma exam despite his neglect of the subject, Maric's early promise was unfulfilled, and she obtained only grade 5 on a scale 1-12, less than half of the grade of the other four candidates in their group. And despite Troemel-Ploetz's attempt in her writings (and in the 'Einstein's Wife' documentary) to play down Maric's Diploma failure in 1900, the fact remains that on the grading system 1-6 her overall final Diploma average grade approximated to some 18 percent less than Einstein's, whereas his was only some 11 percent below the candidate with the top overall grade average (though as the latter majored in mathematics they were not strictly comparable). Of course exam marks are far from everything - but in Maric's case we have nothing else to go on but her Polytechnic grades as a measure of her abilities.

"In historical investigations such as this one must be guided by the hard evidence, not (as Troemel-Ploetz writes) by what is 'plausible,' or 'for all we know.' Nor should we take (as Troemel-Ploetz does in her 1990 article) as serious evidence the mostly third-hand statements obtained many decades after the event from interested parties taking nationalist pride in what they fondly believe to be a Serbian achievement.

"In his book 'Don't Believe Everything You Think' (2006), Thomas Kida reports the research of two psychologists who secretly recorded a meeting held in Cambridge, England. Two weeks later, the participants were asked to write down everything they could remember. Among other gross inaccuracies in their memories, many participants 'remembered' hearing comments that were never actually made. That puts into perspective the utter unreliability of thirdhand reports provided decades later, largely on the basis of which Troemel-Ploetz wrote in her 1990 paper that 'If it were not for the cultural imperialism of the U.S. academic establishment, it might be known in Princeton what is known in Novi Sad [the Serbian home town of the Maric family] - that Einstein-Maric was the scientific collaborator of her husband.' (Troemel-Ploetz, 1990, p. 415)"

This all may sound like a tempest in a teapot of scientific history, but the debate takes on extra interest in light of more contemporary debates over women in science. Are the days of gender discrimination in science and education far behind us, or do women still need to break through the glass pipette ceiling?

• Sydney Morning Herald: Inca language enters digital age
• Science News: Supernovae serve up Cosmic Pops in stereo
• Sun-Sentinel: 'Dead zone' scrambles car locks (via Daily Grail)
• Hindustan Times: India plans Mars odyssey in 2012
• Mars Society tries out a new look for Web site

Moviegoers received a double dose of time-travel fiction this week, with the present-day(s) thriller "Deja Vu" on one hand and "The Fountain," a time-trippy love story, on the other. As we discussed earlier this week, "Deja Vu" reflects a bit more of the current scientific thinking about what time travel into the past, a.k.a. retro-causality, might look like if it were possible. But if you ask the physicists to list their favorite time-travel tales, the ones they mention are golden oldies going back to the days of classic "Star Trek."

Of course, the Starship Enterprise's crew was ready to travel back in time at the drop of a hat (preferably one that covered Spock's pointy ears). But for string theorist Brian Greene, a Columbia University physicist who was a consultant for "Deja Vu," the episode that stands out is "City on the Edge of Forever," in which Dr. McCoy changes mid-20th-century history and it's up to Kirk and the gang to change it back.

As history is rewritten and re-rewritten, items (such as the Enterprise) disappear and reappear to reflect the universe's changing timeline. That follows the same time-travel conventions put in place for the "Back to the Future" time-travel films (and "Star Trek IV: The Voyage Home," for that matter), but does not follow the two main scientific possibilities that Greene and others have laid out:

• The flow of past events is unchangeable, because any effect time travelers had is already reflected in the universe (Stephen Hawking's "chronology protection conjecture").
• The flow of past events can be changed - for example, by sending a signal or a person through a wormhole. But that merely creates a new branching in what is a multitude of universes. The universe from which the time traveler was sent back is unchanged (the "many-worlds" interpretation of quantum mechanics).

Thankfully, as a work of fiction, "City by the Edge of Forever" doesn't have to pass strictly scientific muster, and that's why Greene felt confident giving the episode an endorsement. "Put me down for that one," he told me.

Other physicists who have written about time travel (such as the University of New Hampshire's Paul Nahin and Princeton's J. Richard Gott III) have given thumbs-up to an even more unlikely entrant in the time-travel oeuvre: "Bill and Ted's Excellent Adventure," with a pre-"Matrix" Keanu Reeves as one of the slacker stars.

Of course, Greene is partial to the time-travel films in which he's been personally involved, including "Deja Vu" as well as "Frequency," where he played a time-warped cameo role. And Greene said he's involved in yet another time-travel movie project titled "Mimzy," based on the short story "Mimsy Were the Borogoves" and slated for release next year.

The physicist said he doesn't want to give the impression that time travel is a major focus of research. "Many of us see it as a lingering question in the back of our minds," Greene said. He and his colleagues are even more intrigued by the trippy concepts spawned by string theory - indicating that the universe could follow any of 10⁵⁰⁰ possible courses, and that our course seems to be going down just the right path to allow for the development of stars, galaxies and life.

For some physicists, this multiplicity of potential universes - a seemingly unprovable claim - is a scientific scandal. The criticism is voiced loud and clear in books such as "Not Even Wrong" and "The Trouble With Physics." But for Greene, the idea poses a challenge well worth accepting.

"If this is a feature of the theory, then it's one we have to better understand," he said. "If it is true, it's telling us something mind-bogglingly remarkable about the universe."

The deeper implications of physics will surely set the tone for the start-up of the Large Hadron Collider, scheduled for next year - as well as for the World Science Festival, a science-plus-art celebration scheduled to make its debut in New York in 2008. "I'm one of the festival's co-founders," Greene said.

Here are some of your own thoughts about time travel:

Stuart Greene: "I have always wondered myself about time travel. I was fascinated as a kid. My take on time travel is very simple.

"Let's assume in the future that there is a way to travel back in time. This would imply that time travel would have been infinitely possible, given that someone from the future has already traveled back to the past. And this person who traveled from the future would have transferred this and other technologies and knowledge to the past. From the fact that we know very little about the future, we could conclude that either the traveler from the future is either very selfish (giving his past self scores of the World Series), or he thinks that our knowledge of the future would be detrimental, or there is no future, or time travel is impossible. ...

"My opinion is that time is linear, and the only time travel possible would be to see images of  the past by traveling faster than the speed of light. Kind of sad, but way more interesting not to know the future."

Darrell A. Jones: "If you get a chance, go back and research the Philadelphia Experiment - not the movie, but the actual military research. ... It revealed that the time-travel experiment started out as a failure, then did succeed, yet was still a failure for they had to [go] back because of the hole that had developed and was left open. The scientist involved left a message and documents behind, so that the government did not get the complete files. ..."

Harold Estep, Clarksville, Tenn.: "I once read a novel which dealt with time travel.  It was titled 'Time and Again,' by Jack Finney.  Over the years I have read it three times because the author's premise of how to travel back in time, seemed so believable.  If you like this genre of fiction, I highly recommend you obtain a copy."

That sounds like this month's selection for the Cosmic Log Used Book Club, which highlights books with cosmic themes that you should be able to find at your local library or used-book shop. Before he passed away, Finney wrote a sequel to the novel titled "From Time to Time."

Do you have additional recommendations for time-travel tales - or observations on the facts and fictions surrounding the flow of time and causality? Feel free to add your comments below.

• New Scientist: Boulders dash hopes for Mars landing site
• N.Y. Times (reg. req.): A smarter computer to pick stocks
• Space Daily: Can Russia build a better Hubble? (via Daily Grail)
• 'Nova' on PBS: 'Dogs and More Dogs' 
• The Economist: Don't misunderestimate yourself

The military command in charge of defending North America from aerial threats is beefing up its volunteer corps to keep an eye out for Santa Claus this year – and they're expecting to get a billion Internet hits from wee ones around the world.

The North American Aerospace Defense Command, better known as NORAD, is offering a its traditional Santa-tracking Web site with lots of extra goodies. You can also check out NASA's Santa site, which takes advantage of the same software that helps you watch orbiting probes such as the Hubble Space Telescope as well as the international space station and shuttle.

NORAD's Santa role goes back to the days before NORAD itself technically existed. By now, the tale is almost as well-known as "The Night Before Christmas": how a wrong number was printed in a Colorado Springs newspaper ad, with the result that phone calls to Santa rang instead at the headquarters of CONAD, the predecessor to NORAD. Since that Christmas Eve of 1955, the air command has run a Santa hotline on a volunteer basis.

In 1997, NORAD's Santa operation entered the Internet era and nearly brought down the computer servers devoted to the effort (fortunately, there was no effect on NORAD's "real job"). Back then, the setup could barely handle a million hits - but each year, with the help of NORAD's corporate partners, the system has been upgraded to cope with a flood of seasonal Internet traffic and e-mails.

NoradSanta.com kicked off its holiday season last Friday, and expects to handle more than a billion hits from more than 200 countries and territories. In recent years, the Web traffic capacity has been able to keep up with ever-rising demand, said NORAD's program coordinator, Master Sgt. Tony Hill. But the phone banks and e-mail handling capacity were in need of a significant boost.

"We had 500,000 people who tried to get through last year, but only 52,000 were actually able to get through," Hill told me. "The most common type of call we get is from kids wanting to know where Santa is, and when he's going to be in their town."

This year, Hill said the operation will bring in 800 volunteers for holiday phone duty, compared with 550 last year. He said the number of phone lines has been raised from 35 to 70, and the number of computers set aside for handling e-mail is going up from 12 to 20. Almost 100,000 e-mails were received from children last year, according to last week's NORAD news release.

Christmas Eve is crunch time for the NoradSanta operation, but while the kids are working on their gift lists, they can click onto the Web site to watch preview videos, learn about the history of the program, do a puzzle, download coloring pages and maps, and even listen to holiday music from the U.S. Air Force Academy Band and the Naden Band of Maritime Forces Pacific of the Canadian Navy.

The Web site has an international flavor not only because NORAD is a U.S.-Canadian organization, but also because it's a public service with a worldwide clientele. Information is posted in English and French as well as German, Italian, Japanese and Spanish.

Starting at 4 a.m. ET Christmas Eve, NoradSanta.com will be providing minute-by-minute updates on Santa's travels. The gee-whiz effect will be provided by Analytical Graphics' satellite visualization software (which has applications far more serious than tracking the Jolly Old Elf).

Hill, who is in the midst of his first season as Santa-tracking program coordinator, can hardly wait. "The volunteers are calling every day," he said. "They're getting pretty excited, and I'm getting excited too."

For the nitty-gritty behind St. Nick's technical feats, Roger Highfield's look at the science of Santa Claus is a holiday classic. This engineering analysis, and this rebuttal, delve more deeply into the debate.

I'll be taking the holiday off for a little rest and relaxation (and a little Riesling), but here are a few links to get you through Thanksgiving:

• NASA: What to see in Thanksgiving skies
• Discovery.com: Surprising twists to T-day foods
• Wired.com: The Thanksgiving menu of the gods
• Minneapolis Star Tribune: The myth of tryptophan 

George Wang / UW

A depiction of present-day Earth overlaid with simulated atmospheric oxygen of the early Triassic period. Because oxygen was low even at sea level, animals would have been restricted to very low altitudes, green or light-shaded areas. Red or dark-shaded areas are higher elevations where many animals could not have found sufficient oxygen and so could not have lived or even traversed.

What was the murder weapon for our planet's biggest die-off? The Permian-Triassic extinction is the ultimate cold case, transpiring 250 million years ago. But some scientific sleuths have sketched out a scenario worthy of the trickiest mystery novel - involving a chain of volcanic eruptions, greenhouse-gas emissions, oxygen-deficient oceans, sulfur-loving bacteria and poisonous hydrogen sulfide, the compound that smells like rotten eggs. There are even those who would throw in an asteroid for good measure. The rotten-extinction theory gets a prime-time airing tonight on PBS' "Nova ScienceNow."

The event, which came at the transition between the Permian and Triassic geologic ages, ranks as the most severe of Earth's five mass extinctions (many people say we're in the midst of the sixth extinction). Based on the fossil record, more than 90 percent of marine species died out, along with about 70 percent of all land-based species.

Among the biggest losers were the mammal-like reptiles, which were thought to have given rise to mammals like us. The biggest winners were the dinosaurs, which came into their own during the Triassic and hung around until the Cretaceous-Tertiary extinction wiped them out 65 million years ago.

Most scientists have come to the view that the dinosaurs were doomed by the catastrophic impact of an asteroid or comet that blasted into Mexico's Yucatan Peninsula, though that claim is not beyond debate, and other factors may have been at work as well. The prime cause behind Permian-Triassic event is even more difficult to identify, though most suspect it had something to do with a million-year-long stretch of activity in a huge volcano field known as the Siberian Traps.

The timing was right for the Siberian Traps to play a role, and the volcanoes surely belched out enough carbon dioxide and other greenhouse gases to have an effect on climate. But the consensus is that the greenhouse effect by itself wouldn't explain the depth of the die-off.

This is the mystery that "Nova ScienceNow" traces in flashy TV fashion. For years, researchers such as the University of Washington's Peter Ward have been documenting the Permian-Triassic effect on land species, and looking for a climate-related mechanism that could deliver the killing blow.

"He was looking for a more potent killer," said Lee Kump, a geoscientist at Penn State University, "and we provided that to him."

Kump's research focuses on the tug of war between oxygen and hydrogen sulfide in the world's oceans. "One's going to win, and one's going to lose," he explained. "It's a fight to the death."

Right now, the world's oceans are well-oxygenated, and sulfide-producing marine bacteria are consigned to dismal dead zones where the water has gone anoxic. But Kump and his colleagues believe the situation was reversed at the end of the Permian era: Climate change warmed up the oceans so much that they couldn't retain oxygen, and most marine organisms that needed oxygen died out.

The sulfur-based ecosphere took over - so much so that toxic hydrogen sulfide bubbled up from the oceans into the atmosphere, killing off land species as well.

"What really looks like a universal way that this has happened is this global warming, leading to this terrible gas chamber atmosphere, killing off life in the ocean and land," Ward says during the "Nova" program. "It's not so much stuff from space that gets you, it's your own planet."

Computer simulations of Permian climate change appear to confirm this scenario, Kump said.

"Probably the smoking gun for the role of hydrogen sulfide in this mass extinction was the discovery of particular traces of ancient bacterial life in China and Australia from this Permo-Triassic layer," he told me. Such bacteria would need light as well as hydrogen sulfide to survive, he said.

It would take millennia for the sulfurous sickness to run its course, and for Earth's oceans to bounce back to their oxygenated state.

Could it happen again, in an age when CO2-driven climate change is a concern?

"One of the concerns about global warming is that it will affect that tenuous balance of ocean oxygen," Kump said. He subscribes to the view that there's a critical threshold of carbon dioxide levels, and that passing the threshold can set off a cascade of unpleasant environmental changes.

"All sorts of positive feedbacks come into play once this threshold has been exceeded," he said. "Those feedbacks are lurking there. That's the problem with positive feedbacks, you don't know if they're going to kick in until it's almost too late."

So have scientists finally nailed down the case? Kump, Ward and many others are pretty confident about the "sick Earth" scenario, but other investigators aren't so sure. Luann Becker, an earth scientist at the University of California at Santa Barbara, said even a climate catastrophe wouldn't have been enough to push the Permian ecosystem over the edge.

"It just simply cannot be done without having more than one catastrophe happening at the same time," she told me today.

Becker has proposed that a cosmic collision, perhaps occurring off the coast of Australia, provided an additional push. Other researchers point to a possible Antarctic impact as the culprit.

A massive asteroid impact could have set off a global chain reaction, exacerbating the climate crisis and sparking continued volcanic activity, Becker said.

She said she's working on yet another TV show about the Permian-Triassic extinction - a documentary that will be part of the National Geographic's "Earth Shocks" series. Her perspective on the puzzle will be that it takes more than one long stretch of global warming to deliver a Permian-sized death blow: It also takes a space rock. 

"We're going to revisit the idea that the catastrophes at the end of the Permian and the end of the Cretaceous are things that were somewhat unique - but how can you call it a coincidence when it's happened more than once?" she said. "We have volcanism all the time, and yes, volcanoes have their effects. But we never see extinctions like the extinctions we're talking about, unless the two are coming together."

So don't close the file on the Permian-Triassic murder mystery just yet. For more background on the case, check out our "Earth's Timeline" interactive dossier.

"Nova ScienceNow" is offering much more in tonight's episode, including a look at the controversial effort to reconstruct the 1918 pandemic flu virus, the rise of sociable robots (featuring MIT's Cynthia Breazeal) and a tale of papyrus scavenging. For Webheads, the coolest part is that all these segments will be watchable online after tonight's premiere.

• Detroit Free Press: Teen does nuclear fusion in parents' basement
• Discover Magazine: 25 greatest science books of all time 
• The New Yorker: Calls of the wild turkey
• N.Y. Times: A free-for-all on science and religion

We've gone back and forth over the role that Albert Einstein's first wife, Mileva Maric, may have played in the development of the special theory of relativity. Did she help her husband with the concepts or mathematics behind the theory? Or was Albert simply being generous when he referred to "our work"? We've heard from Allen Esterson, a physicist and historical author who's skeptical that Maric had much of an impact, and now I've gotten the other side of the story from Senta Troemel-Ploetz, a German linguist and author who has championed Maric's role:

"Dear Mr. Boyle: I am very sorry to be so late in answering - I was in Israel, actually reading the newly released Einstein correspondence and being the first person to do so, and then on a lecture tour in Germany. Your e-mail reached me when I could not read all my mail.

"As to your question: I do not know Esterson. Is he a historian of science, or just another physicist or journalist turned Einstein expert, without being able to read German or knowing anything about the historical context of women studying in Switzerland around the turn of the century?

"A case in point is [John] Stachel, who explains the "our work / our paper" in Einstein's letters with Einstein being in love, i.e., not meaning what he says. He is in a tradition that always attributes achievement to men even if the men themselves claim their wives were the authors. John Stuart Mill was still said to be in love when he argued his wife was a co-author - his wife was long dead.

"More importantly it seems that neither Stachel nor Esterson take Einstein at his word when he says even stronger things:

• "How happy I am to have found an equal in you (eine ebenbuertige Kreatur) who is as strong and independent as I am."
• "Until you are my dear little wife, we want to eagerly work together scientifically so that we won't become philistines...."
• "When I look at other people, I realize what I have in you / what mettle you are made of."

"Einstein-Maric was Einstein's first critic, a most important function for anyone, but especially a dialogic creature like Einstein. She was with him 24 hours from January 6, 1903 on, i.e., during the most important years before the so-called annus mirabilis. She had the same training and more than Einstein. It is plausible that she was his collaborator, his intellectual and emotional support. For all we know, she may have done what Sophie Taeuber-Arp did for Jean Arp: 'to translate his ideas into reality.'

"It is quite possible that the 'our,' written very early in their collaboration, is an understatement rather than an overstatement for what happened once they were married. ..."

Later, Troemel-Ploetz wrote an addendum:

"Sophia Yancopoulos, an American physicist, speaks of the 'subtler issues of collaboration,' and we are far from knowing much about them. What we do know is that again and again the work of creative women was appropriated by men in the arts and the sciences, and men who fairly give credit to their female collaborators are the exception. Einstein was a very normal man, as I said in New Orleans anno 1990."

Feel free to add your further comments about Mrs. Einstein and her math below.

• Neverworld: The picture of the century
• Science News: Dashing rogues
• New Scientist: Everyday wisdom behind Jedi tricks
• Metro: Is this the face of Jack the Ripper?
• LiveScience Blog: Leonid meteor shower was a stinker

Efforts to link the origins of the Dead Sea Scrolls with an ancient toilet site became the butt of a joke or two this week – and have touched off another round of debate over scroll history. Were the scrolls actually written by an eccentric sect based in Qumran near the Dead Sea? Does the ancient latrine really prove anything? University of Chicago historian Norman Golb, a tenacious scroll skeptic, thinks not.

Golb scorns the conventional wisdom that a community of Essene monks in Qumran was responsible for some of the oldest surviving Jewish texts. Rather, he points out that the scrolls represent a variety of traditions in Jewish religious thought, and surmises that they ended up in the caves around Qumran because refugees from a Jewish revolt in Jerusalem stashed them there. Qumran itself was likely some sort of fortress or pottery-making center, Golb says.

Eleven years ago, he advanced his ideas in a book titled "Who Wrote the Dead Sea Scrolls?" - and ever since then, he's been cast as something of a voice crying in the wilderness. Until this year. That's when a pair of Israeli archaeologists generated a lot of press with similar claims that the settlement at Qumran didn't have anything to do with the sacred scrolls. Now Golb is not so alone in the academic wilderness.

So what's the big deal? Over the years, the Dead Sea Scrolls have taken on an extra measure of mystery because of their association with a messianic sect that was active in Jesus' day. Some experts have drawn extensive parallels between the practices of early Christians and the Essene community at Qumran. If it turns out that the scrolls have a  different origin, historians would have to reconsider the linkages between Judaism and early Christianity - and where the scrolls figure into those linkages.

That's why every little finding from Qumran - even animal bones and latrines - can set off a scrum. In an e-mail, Golb noted that he hasn't yet seen the published research about the latrine discovery, but he did put together some bullet points based on his reading of this week's press release from the University of North Carolina at Charlotte (full PDF file). Here are Golb's observations:

"1) The author acknowledges the statement in Deuteronomy (Chap. 23, verses 13-14) commanding fecal sanitation outside of an inhabited encampment, but afterwards implies that the practice was 'revived' by a sect supposedly living at Khirbet Qumran. This, however, is merely a theory held by the author and based upon the widely believed assumption that a sect actually lived at Qumran. On the view, however, that Jews who were not sectarians lived at Qumran, the finding implies nothing more than that during the Intertestamental period those of them living in encampments or fortresses followed the aforementioned Biblical rule of Deuteronomy.

"The very most that can be said of the author's claim is that the finding does not in itself disprove the theory that a sect lived at Qumran - but it doesn't prove it either.

"2) To bolster his claim, the author alludes to two passages in the Dead Sea Scrolls; he is quoted in the news release as saying 'This group is very strict and they observe this practice rigorously - in one text it says go 1,000 cubits, and in another text 2,000 cubits....' The two texts to which the author alludes, however, are (a) the 'Temple Scroll' and (b) the 'War Scroll.' These texts are both apocalypses, the one describing an idealized Jerusalem Temple of future times, and the other cataclysmic battles between forces of good and evil.

"The Temple Scroll mentions a latrine placed three thousand cubits beyond the confines of the holy (Temple) precincts of Jerusalem, while the War Scroll describes a latrine placed two thousand cubits beyond the confines of the encampment of the (Israelite) forces of good. There is no proof whatever that these apocalypses served as models for actual buildings or structures of Intertestamental times; the varying measurements evidently derived from the writers' own imaginations.

"The author states in the news release that the latrine found by him was located five hundred meters from the Qumran settlement, or approximately 750 cubits. That would be two-thirds of the 'one thousand cubits' that the author claims is found in one of the two aforementioned (apocalyptic) texts but, despite the author's assertion, such a measurement is found in neither of those texts. The 'two thousand cubits' of the War Scroll would, on the other hand, bring one far beyond the discovered latrine, and the 'three thousand cubits' of the Temple Scroll all the more so. The attempt to treat apocalyptic imaginings in the Scrolls as reflections of historical reality is a most unfortunate development in the rhetoric of traditional Qumranology. The argument of the author boils down to a similarity between the fact that the Temple Scroll locates the latrine three thousand cubits 'northwest' of the holy precincts, while the latrine found 500 meters to the north of Qumran is not precisely due north but slightly northwest.

"By normal standards of identification of historical sites, this is not nearly enough to warrant the author's specific identification of Khirbet Qumran as a sectarian settlement, but seems rather to reflect a personal belief of the author.

"3). The description in the news release of Josephus's statement regarding the Essenes' personal habits is misleading. Josephus does not state that the Essenes refrained from defecating on the Sabbath because of a prohibition against walking outside of their settlement. Cf. his complete statement in Jewish War II, ed. Thackeray, pp. 379-381. The statement in the news release that 'Josephus described very similar exotic toilet practices among the religiously strict sect known as the Essenes' seems at first like an attractive analogy until one realizes that it begs the question.

"4). The news release fails to state why the author and his colleague turned to a parasitologist in France for the evaluation of the unearthed specimens rather than consulting with one in Jerusalem, the closest scientific center to the site under discussion."

Between the Qumran toilet and the Mexican monolith, this has been a big week for archaeology. So feel free to comment below on the mysteries surrounding the Dead Sea Scrolls, or ancient Aztec lore - heck, even the Bosnian pyramid.

• The Economist: Tilting at windmills
• Technology Review: Facing the dangers of nanotech
• SmartMoney: Fly me to the moon
• Salt Lake Tribune: Rocket motor test gives ATK a boost
• The New Yorker: What was Descartes thinking?
• Cosmic Log in Spanish: Los evangelios de la cienca

It might seem obvious that dwelling on money (or lack thereof) makes people focus more on themselves and less on others – after all, even the Bible says the love of money is the root of all evil. But is that the square root or the cube root? Experiments detailed in this week's issue of Science quantify how thinking about money, even subliminally, affects our behavior for good or for evil.

The researchers behind the study - University of Minnesota marketing professor Kathleen Vohs, Florida State University graduate student Nicole Mead and University of British Columbia doctoral student Miranda Good - started out with the proposition that thinking about money leads people to behave more self-sufficiently and less cooperatively. So they designed nine psychological experiments aimed at testing whether reminders of money would lead people to focus more on their individual tasks and less on what others were up to.

In some cases, the references to money were built into the experiment: For example, some subjects were asked to put together phrases like "a high-paying salary." Others read essays about growing up rich or poor, or played a game of Monopoly. Sometimes the reminders were more subliminal: Subjects filled out questionnaires while they sat in front of a computer screen that displayed dollar bills floating past, or worked at desk facing a poster showing different denominations of currency.

The experiments' control groups did the same tasks, but without encountering references to money. The screensaver showed fish floating past, or the poster showed a flower garden.

The point of each experiment wasn't usually the task itself, but how the references to money changed the way people behaved as they did the task.

The money-conscious groups consistently worked longer at their individual tasks than the control groups (or the people who read about growing up poor). But they also put less effort into helping out others, based on manufactured situations where assistance was requested.

For example, they donated an average of 77 cents to a "University Student Fund," compared with $1.34 for the control group. When a box of pencils was spilled "accidentally" on the floor, they picked up an average of 18 pencils, compared with 20 for the control group. They even kept their chairs farther away from each other (118 inches vs. 80 inches for the control group).

In all, about 450 people participated in the experiments, Vohs said. "We found no differences as a function of country of origin, no differences between men and women, no differences with respect to whether they grew up with wealthy or meager resources," she told me today.

The bottom line is that dwelling on money changes things for better or for worse, depending on the situation. Here's how the researchers put it in the last paragraph of their Science paper:

"The self-sufficient pattern helps explain why people view money as both the greatest good and evil. As countries and cultures developed, money may have allowed people to acquire goods and services that enabled the pursuit of cherished goals, which in turn diminished reliance on friends and family. In this way, money enhanced individualism but diminished communal motivations, an effect that is still apparent in people's responses to money today."

Is there any way to put this philosophy to practical use?

"Certainly you can use these results to one's advantage," Vohs observed. "As a business owner or a manager, if you would like people to work cooperatively on a project, you would be better served by minimizing the references to money. But on a personal level, if you want to motivate yourself to achieve a goal, you might want to use that concept of money."

It doesn't even have to be real money.

"It's the mere presence of money or the activation of the concept of money, but it wasn't anything about earning money, it wasn't about rewards, it wasn't about salaries," she said. "It was about activating the concept of money, even at a level that's beneath awareness."

So let's say you'd like your teenage daughter to be more diligent about cleaning her room or doing her homework. Could you get away with putting up a poster or giving her a screensaver rather than promising to raise her allowance?

Vohs chuckled at that, but agreed that "it doesn't have to be about the attainment of money, just monetary reminders." Now she and her colleagues are looking at how to apply that insight in the real world. "One of my next goals is to look at vulnerable populations, like the elderly, and see if we can promote self-sufficiency for them," she said.

And that finding - about the power of money as a concept as well as hard currency - might not be so obvious. "I certainly don't think that it was something everyone knew about."

For more perspectives on the research, you can check out the news releases from the University of Minnesota and Florida State University, as well as The Associated Press' story and this report from ScienceNow, the journal Science's news site.

Blue Origin, the secretive rocket venture backed by Amazon.com billionaire Jeff Bezos, says this week's first test launch in West Texas was a success - but details are still hard to come by. Over the next four years, Bezos' venture plans to offer passenger rides to the edge of outer space, 62 miles (100 kilometers) up and back, but this first test was an unmanned flight that reportedly went no higher than 1,000 feet (300 meters).

"We're excited to see this successful first flight as we experiment with engine and vehicle designs," Rob Meyerson, Blue Origin's program manager, is quoted as saying in the local newspaper, the Van Horn Advocate.

Blue Origin is based in Kent, Wash., near Bezos' Seattle home base, but about 250 employees and family members converged on the launch site near Van Horn, Texas, to take in the maiden test launch at 7:30 a.m. CT Monday, the Advocate says

"Van Horn was very friendly and welcoming to our staff and their families. The town made us feel very much at home — it made the trip highly enjoyable for everyone," Meyerson told the newspaper.

• JHU: Exotic relatives of protons and neutrons discovered
• Scientific American: Cancer clues from pet dogs
• Seattle P-I: Going for a blast into the real past 
• The Guardian: We will not be alone in 2056

NASA / JPL-Caltech

The Opportunity rover captured this stereo image of Mars' Victoria Crater on Oct. 5. Viewing the image through red-blue glasses produces a 3-D effect.

To mark the Opportunity rover's 1,000th Martian day of operation, NASA has released a panorama of the crater that the robot is currently exploring – and you've got to see this 8-meg bad boy in 3-D. So dig out the red-blue glasses and take a virtual field trip to Mars.

The wide-angle view looking down into Victoria Crater was actually taken more than a month ago, back on Sol 959 (a sol is the Martian day, equal to 24 hours, 39 minutes and 35 seconds). But Opportunity hasn't wandered away from Victoria - it's continuing to survey the half-mile-wide (800-meter-wide) crater's rim, looking for the best place to venture down into the dune-covered interior.

Victoria's big attraction is the layered bedrock on the way down. The crater is about 230 feet (70 meters deep), which should provide an unprecedented opportunity to analyze the Red Planet's geological history in depth. If Opportunity's luck holds up, it will likely still be working on the rock analysis when it marks its third full Earth year on Mars, next Jan. 24. As I've said for months: Not bad for a mission that was originally scheduled to last just 90 days.

The Spirit rover, Opportunity's twin on the other side of the planet, marked its 1,000-sol milestone a couple of weeks ago - and it's still making scientific observations in place while it waits for the winter sunshine to strengthen. Once the solar-powered Spirit starts generating enough power to support mobile operations again, it will head back toward a feature called Home Plate to study some deposits that have been intriguing scientists for months.

Now, about those 3-D glasses: The rovers have produced scores of stereo images that have been converted to anaglyphs - that is, pictures that create the illusion of 3-D perspective when viewed with the kinds of red-blue spectacles associated with bad sci-fi flicks.

I've grown accustomed to carrying a cardboard pair of 3-D glasses with me wherever I go, just in case I run into an anaglyph I can't resist (or someone I need to impress with my geekitude). You should be able to find the spectacles at novelty stores, and NASA's STEREO mission even provides directions for making your own. If you really want to impress your geek friends, you might want to get something more durable than cardboard.

You can use these glasses for much more than the Mars missions: Eventually, the STEREO spacecraft will be providing 3-D images of the sun, and there are already some practice images up on the STEREO Web site. Besides, you never know when "The Creature From the Black Lagoon" will make a reappearance.

• IEEE Spectrum (reg. req.): The new search for E.T.
• Esquire: Big freakin' laser beams in space (via Slashdot)
• Nature: Sharpest cut from nanotube sword
• Space.com: Nearby stars come out of hiding
• Slate: I'm a math moron

'Tis the season for annual reports, and now the global space industry has a doozy: a full-color, 176-page book put out by the Colorado-based Space Foundation, simply titled "The Space Report." The inaugural report estimates the total size of the space economy at $180 billion in 2005, based on the foundation's reading of government budgets and industry revenues worldwide. And although space tourism accounts for less than 1 percent of that total, the foundation's president and chief executive officer says that little wedge of entrepreneurship will be "exceedingly important" in the years to come.

The "entrepreneurial effect" is one of the top trends highlighted in this first of what the foundation hopes will be an authoritative series of annual reports, said Elliot Pulham, the president and CEO. Pulham told me the space tourism factor plays an outsized role because it's bringing "outside-the-box" thinking to the industry, and because it's sparking a fresh wave of public interest in the final frontier.

"Creating public interest, both through what NASA's doing with human exploration of the solar system and through what these entrepreneurs are doing, trying to make space accessible to everyone, has a huge upside," he said. That could fire up the next generation of students about career opportunities in aerospace - which is of increasing concern to industry leaders.

"It's hard to quantify that in terms of dollars," Pulham said.

But the Space Foundation has put a lot of work into quantifying other aspects of the space business, blending estimates from governments as well as private industry to arrive at the big $180 billion picture. That bottom line includes:

• $80 billion in revenue for commercial satellite services.
• $57 billion in budget allocations for U.S. government space budgets, both civilian and military.
• $12 billion for other governments' space budgets.
• $29 billion in revenue for commercial infrastructure, such as satellite manufacturing and launch services.
• $1 billion for commercial institutional infrastructure, such as insurance and industrial research and development. 
• Less than $1 billion for commercial space transportation services, such as space tourism.

Of course, these figures are based on 2005 activities, so they don't include the $500 million NASA has set aside over the next four years for its Commercial Orbital Transportation Services program, or COTS, which many see as a relatively small but vital sparkplug for private-sector space travel.

Pulham said COTS has inspired even the established satellite operators to start thinking outside the box. For example, he recalled a recent conversation with one satellite executive who described a scheme under which antennas could be mounted on the backsides of a fleet's worth of telecommunications satellites - providing a low-cost, commercial successor to NASA's maxed-out Deep Space Network.

Pulham likes the fact that "Old Space" companies such as Lockheed Martin and ATK are partnering with "New Space" companies such as Bigelow Aerospace and Rocketplane Kistler. "The more fuzzing of the lines, the better," he told me.

Lines are also being fuzzed between satellite data and terrestrial databases: The mashups of satellite imagery and locational tags serve as one set of examples; new types of GPS-based applications such as Caffeine Finder and RFID trackers provide yet more signposts toward the future.

"Space is becoming the background architecture that everything runs on, and we don't even realize it," Pulham said.

The Space Foundation wants to help people realize it, through the annual "Space Report" as well as through a new index of space equities that will be updated quarterly.

The Space Foundation Space Index follows 30 companies that derive a significant portion of their revenue from space activities, ranging from Boeing and Lockheed Martin to the XM and Sirius satellite radio services. Pulham noted that the index increased by more than 8 percent between June 2005 and June 2006 - outperforming the NASDAQ and S&P 500 indices.

The point isn't so much to provide a new financial instrument for investors as it is to provide a yardstick for tracking the ups and downs of outer-space commerce from quarter to quarter, and year to year. "I think this model, as a new way of understanding that this is a no-kidding industry, is a real contribution," Pulham said.

Correction for 12:30 p.m. Nov 15: When referring to COTS, I initially wrote "billion" instead of "million" - thanks to Clark Lindsey for alerting me to the error.