What should be the goals of the next generation of X Prizes? Peter Diamandis is just the man to ask the question. It was Diamandis’ foundation that led to the launch of a private manned spacecraft in 2004, and since then his team has gone on to sponsor an automotive X Prize offering $10 million to anyone who can produce a marketable car that can get 100 miles per gallon. Sixty teams are at work on that one, and prizes focusing on renewable energy are also in the works. The big fish in the pond is the Google Lunar X Prize, which offers $30 million for the first privately funded robotic mission to the Moon.
Nor is Diamandis alone. In fact, the landscape is awash in prizes. The Virgin Earth Challenge, brainchild of British aviation mogul Richard Branson, offers $25 million to anyone who designs a viable way to remove greenhouse gases from the Earth’s atmosphere. For that matter, what about the Saltire Prize, for which Scotland has found £10 million for renewable energy breakthroughs? The US Department of Energy is in on this act as well, with $4 million in the offing for the winner of the Freedom Prize, designed to reduce US dependence on overseas oil.
It’s no surprise, then, to find Diamandis pondering what a truly long-term X Prize might look like. On Friday, he’ll discuss ideas that are seemingly impossible but could change the world in a talk sponsored by the Long Now Foundation in San Francisco. If you’re unable to be there, Diamandis has put a video up on YouTube asking for input on the question (you can send in your thoughts here). He wonders what would have happened if, in the 1870s, someone had offered a major cash prize for a heavier than air flying machine, or a way to communicate instantly between London and New York: “People would have thought you were nuts, that these are literally impossibilities, magic.” But we know the outcome.
A future X Prize, Diamandis opines, might be focused on a colonizing mission to Mars. Or it might involve transforming energy into matter (here he recalls Star Trek‘s transporters). Maybe we can take the prize notion to outrageous limits and suggest an interstellar component. Heck, we’ll even offer a head-start. In a recent post on his systemic site, exoplanet hunter Greg Laughlin offered an interesting comment on Alpha Centauri, one worth keeping in mind for would be prize designers:
We’re fortunate that we’ve arrived on the scene as a technological society right at the moment when a stellar system as interesting as Alpha Cen is in the very near vicinity. During the last interglacial period, Alpha Cen did not rank among the brightest stars in the sky. A hundred thousand years from now, the Alpha Cen stars will no longer be among our very nearest stellar neighbors, and in a million years, they will have long since faded from naked-eye visibility. At the moment, though, Alpha Centauri is drawing nearer at 25 km/sec, a clip similar to the Earth’s orbital velocity around the Sun. It’s as if we’re on the free trial period of an interstellar mission…
A free trial period is usually enough to quicken the pulse of consumers. So why not use it to tantalize potential prize donors with the prospect of a truly long-term, outlandishly expensive prize, one designed to spur efforts to put a man-made payload with the capability of returning scientific data into the Centauri system? The data returned could well prove less significant than the breakthroughs achieved to make the journey.
Prizes capture the imagination and can create new ways of thinking because the people involved in them often put far more time, energy and money into the process than the prize itself justifies. You wanted long term, Peter, so how about a Centauri Prize for the first interstellar flyby?
A massive gamma-ray burst detected last March, believed to be the brightest ever seen, turns out to have been aimed directly at the Earth. A narrow jet that drove material toward us at 99.99995 of the speed of light is revealed in the data, itself wrapped within a somewhat slower and wider jet. The best estimates are that an alignment like this occurs only once every ten years. Says Paul O’Brien (University of Leicester, and a member of the team working on the Swift satellite):
“We normally detect only the wide jet of a GRB as the inner jet is very narrow, equivalent to not much more than 1/100th the angular size of the full Moon. It seems that to see a very bright GRB the narrow jet has to be pointing precisely at the Earth. We would expect that to happen only about once per decade. On March 19th, we got lucky.”
It could be said that any information we get about GRBs is in a sense lucky, given how tricky are the constraints for observing them. And indeed, another GRB just degrees away from this one was already under observation when the big blast went off, making it hard to miss. But wherever the GRB, the Swift satellite is making it possible to gather data from it, finding the original explosion and quickly alerting optical telescopes on Earth — so that they can begin observing within minutes. In this case, the blast was so intense that it temporarily blinded Swift’s X-Ray Telescope and UltraViolet/Optical Telescope, and its visible light was quickly being examined by wide-field cameras in Chile.
Image: This artist’s concept shows the “naked-eye” GRB close up. Observations suggest material shot outward in a two-component jet (white and green beams). Credit: NASA/Swift/Mary Pat Hrybyk-Keith and John Jones.
All of this gives us the opportunity to study a GRB from gamma-ray to radio wavelengths, examining what happened to one massive star that exhausted its fuel. GRB 080319B seized the attention of the world when it became clear that the burst was actually bright enough to be visible to the unaided eye, cresting at a magnitude of 5.3 even though the star that spawned it was located over 7.5 billion light years away. The bright afterglow is the result of the gas jets muscling out from the collapsing stellar core, striking gas the star had previously shed and heating it.
The paper is Racusin et al., “GRB 080319B: A Naked-Eye Stellar Blast from the Distant Universe,” slated for publication in Nature tomorrow and available here.
Addendum: Interesting comment by Alex Filippenko (UC Berkeley) in a just arrived news release (not yet up on the Berkeley site): If the supernova that produced this GRB were located 6000 light years from us, the event would have appeared as bright as the Sun. Filippenko calls it “…the most powerful event ever seen in human existence.”
Who would have thought the planet Mercury would prove so useful in explaining how solar sails work? The Messenger spacecraft’s recent course adjustment maneuvers have proven unnecessary because controllers have been able to use its solar panels creatively, harnessing solar radiation pressure (SRP). And what better place to shake out such methods but on your way to a Sun-drenched planet that moves in an environment where SRP can be eleven times higher than that near Earth?
It may come as a surprise that we are already using solar sailing techniques on operational missions, but Messenger is not the first. In fact, we can go back to another Mercury mission, Mariner 10, which took advantage of the effect of solar photons on its twin solar panels, each about nine feet in length and three feet in width, a highly usable 55 square feet that not only generated power but got the spacecraft out of serious trouble. Launched in 1973, Mariner 10 ran into problems with its stabilizing gyroscopes and, later, with flaking paint on its high-gain antenna. The latter confused the spacecraft’s navigational sensors and caused it to lose its lock on the guide star Canopus.
The result: On March 6, 1974, Mariner 10’s troubled star-tracker induced a roll that lasted forty minutes, using up vital attitude control gases as the spacecraft tried to stabilize itself. Here’s what happened next, as told in the mission report:
On 11 March the spacecraft was not oriented in roll on the star Canopus as it went out of the star sensor’s view early in the morning due to the distraction of stray bright particles. However, the spacecraft was stable in its roll attitude because the tilt of Mariner’s solar panels is such that solar pressure on the panels created a torque counter to the natural drift in roll of the spacecraft. This stable condition was the result of skilled testing over the weekend to develop various combinations of panel tilt angles. One panel is at 66 deg and the other at 66½ degrees. The Mariner 10 roll attitude can be controlled by judicious tilting of the spacecraft solar panels.
So there you are, solar sailing at work, or at least, solar attitude correction made possible by the transfer of momentum from solar photons hitting those big solar panels. Messenger has done Mariner 10 one better by tilting its solar panels to adjust its trajectory, ensuring that the spacecraft would meet the 200-kilometer Mercury flyby point (it missed by a mere 1.4 kilometers), a targeting feat that Jim McAdams (Johns Hopkins Applied Physics Laboratory) describes as ‘spectacular.’
Look for more of the same on Messenger’s second Mercury flyby as controllers continue to use solar radiation pressure to control trajectory. In this case, the combination of spacecraft attitude and solar array orientation should continue to reduce the need for trajectory correction maneuvers using more traditional thrusters. By the time Messenger goes into orbit around Mercury in 2011 following gravity assist flybys of Earth, Venus (twice) and Mercury itself (three times), the use of solar radiation pressure should be better understood in a critical operational environment.
Image: Artist’s impression of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft in orbit at Mercury. MESSENGER launched on Aug. 3, 2004, and will begin a year-long orbital study of Mercury in March 2011, materially aided by solar sailing techniques. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington.
We’re closing on the second Mercury flyby, which takes place on October 6. The vehicle is now 90.04 million kilometers from the Sun and 140.9 million kilometers from Earth. All of the practical information we can learn about solar sailing from such encounters points to the need to get a working sail into near-Earth space for rigorous testing. With NanoSail-D’s duplicate ready to go, let’s hope a dedicated space sail can find a ride to orbit to extend the hard won experience of the Messenger mission.
Making contact with an extraterrestrial civilization, whether by microwave, laser or neutrino, highlights the problem of time. Suppose you are looking for a newly emerging technological culture around another star. When do you transmit? After all, even the most powerful signal sent to Earth a million years ago would have no listeners, which is why some have suggested putting actual artifacts in promising solar systems. Rather than transmitting over time-scales measured in eons, you leave an object that can be decoded and activated for communications. All kinds of interesting science and science fictional scenarios flow from that idea.
But what if you want to contact not just a few highly targeted systems, but instead send a signal intended for everyone in the galaxy with the means to receive it? As John Learned (University of Hawaii) and team speculate in a new paper, one way to do that would be to select highly visible and important stars to carry your message. Cepheid variables are a natural fit. Because of the clear relation they show between luminosity and variability, they’ve helped us figure out distances on a galactic scale, and have been crucial in our studies of the Hubble constant. As well as being important to science, they’re bright and easily observed, like the ‘water-hole frequencies’ an obvious place to search for signals.
Image: This NASA Hubble Space Telescope image of a region of the galaxy M100 shows a class of pulsating star called a Cepheid Variable. Though rare, these stars are reliable distance indicators to galaxies. Could they also be put to work as galactic communications beacons? Credit: Dr. Wendy L. Freedman, Observatories of the Carnegie Institution of Washington, and NASA.
Exactly how might a super-civilization modulate an entire star? The authors speculate about using neutrinos for the purpose:
Neutrinos would seem to be the ideal delivery means for transporting a pulse of energy to the stellar core, both due to penetration ability and to speed. If one wanted to employ infalling material as the trigger, this disturbance would propagate at near the local speed of sound, and might well evaporate prior to reaching the core in any event. Neutrinos of about 1 TeV would have an attenuation length of about 106 km at solar densities. We have not modeled Cepheids in order to determine the optimum neutrino energy, but it is irrelevant for the present discussion: we leave it as an engineering problem for the star tickling civilizations out there. The initial ?avor mix of the neutrino beam makes little difference since oscillations will mix the ?avors and in any event the cross-sections are ?avor independent.
The Star Ticklers — it sounds like a 1950’s title, maybe from one of the Ace science fiction double paperbacks. And it’s a curiously provocative concept. Deeply interesting here is the supposition that, if a modulated signal were being broadcast through the use of Cepheid variables, we might already have evidence for it in the abundant data collected about these stars. Normally, Cepheids are studied through a small number of randomly spaced observations conducted over a long period of time. The authors run through the methods of data collection and analysis, and point to places where those methods might actually mask the presence of an interesting signal. And they suggest a way to pull a signal, assuming one is there, out of the noise. This is also worth quoting:
Thereafter the conclusive ?nding of an ETI signal would come about by identi?cation of regularities which are hard to understand from any natural oscillator, such as involving repeated complex sequences, prime numbers, a limited “alphabet” (e.g. something akin to the familiar ASCII code), or even an apparent raster-like arrangement. At this point we cannot but fall back upon the supposition that we will recognize unnatural stellar ?uctuations when we see them. In sum, we think the normal method of employing Fourier transforms (with windowing, gap ?lling, long term averaging, etc.) and other methods in common use to analyze the periodicity of Cepheids may cloud the discovery of intentional modulation, and that cycle-by-cycle periods need to be examined.
The prospect that existing records of Cepheids and possibly other variables might contain the signature of a galactic internet is an exciting one indeed. It’s also interesting to look at the mechanism involved in generating the signal. The neutrino trigger generator might consist of a power station perhaps 100 AU out, one that draws energy from the radiation of the Cepheid itself, accumulating it over the course of a complete cycle and then setting off the trigger pulse. An unstable stellar system becomes the universe’s biggest signal amplifier.
Anything that helps us with what the authors call the ‘needle in a haystack’ problem is all to the good. We want to find ways to narrow the SETI search in productive directions. Here Cepheids are useful because the entire galaxy contains only about 500 known examples. Giant yellow stars massing between five and ten times the mass of the Sun, with 103 to 104 times solar luminosity, Cepheids would be not only visible but highly studied by any civilizations trying to learn about the cosmos. That makes them a productive medium for the kind of culture that can muster the resources to impose a signal upon them.
The paper is Learned et al., “The Cepheid Galactic Internet” (abstract).
In Centauri Dreams, Paul Gilster looks at peer-reviewed research on deep space exploration, with an eye toward interstellar possibilities. For many years this site coordinated its efforts with the Tau Zero Foundation. It now serves as an independent forum for deep space news and ideas. In the logo above, the leftmost star is Alpha Centauri, a triple system closer than any other star, and a primary target for early interstellar probes. To its right is Beta Centauri (not a part of the Alpha Centauri system), with Beta, Gamma, Delta and Epsilon Crucis, stars in the Southern Cross, visible at the far right (image courtesy of Marco Lorenzi).
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