by Paul Gilster | Aug 5, 2008 | Culture and Society, Sail Concepts |
I’ve been surprised by the sizable reaction to my bet with Tibor Pacher, not just in terms of comments here but in related e-mails. For those of you who missed the original post, I found Tibor’s prediction that the first interstellar mission would be launched by 2025 to be an irresistible target. Tibor posted the prediction on the Long Bets site, and the way this works is that someone willing to make a bet on the prediction puts down the money upfront and challenges the predictor to match it.
Negotiations follow, the outcome being that if the terms are worked out and the bet is accepted, it is finalized. Both parties send in their money, and the money grows over the years in a long-term investment portfolio called the Farsight Fund. Ultimately, either the Tau Zero Foundation or (Tibor’s choice) the SOS-Kinderdorf International, will enjoy the result.
Now that Tibor and I have finalized the terms, the details will go up on Long Bets as soon as our funds arrive (which should be in a few days). Until then, I thought you might be interested in some of the details we settled upon. Among other things, we have agreed that:
- The mission can be a manned or unmanned, either a flyby probe or a spacecraft intended to be captured by the target star’s gravitational field. The mission will have been designed expressly as a mission to another star, and as not an outer-Solar System mission that simply keeps going, with a star more or less along its route of flight.
- The allowed launch location of the spacecraft is any place in the Solar system within the orbit of Neptune, either from the surface of a Solar System body or from any orbital position.
- The mission duration must be less than 2000 years.
- As a minimum requirement for the mission the spacecraft shall be capable of delivering data for at least one scientific measurement.
The actual text of these details and a few other matters will be posted soon on the Long Bets site — I’ll provide the link once it’s available. And as I’ve told more than a few people, I would be delighted to be proven wrong on this matter, for it would mean that our technology is advancing at a far faster clip than I currently assume, and also that enough public support will exist to make such a mission possible. That sort of optimism (even though I think it’s premature) is a bracing tonic after the weekend’s loss of NanoSail-D, a solar sail deployment experiment.
The last time I wrote about solar sails, I noted the frustration that the team at Marshall Space Flight Center in Huntsville must have been feeling about the concept. That frustration grows out of knowing that this technology is ready for space-testing but perennially short of resources, and I suspect it is shared among NASA scientists at all centers involved in sail work. The NanoSail-D deployment experiment, involving a 100-square foot sail, seemed made to order, since it hitched a ride aboard a SpaceX Falcon rocket to which NASA Ames had already committed.
Now we’ve lost both the SpaceX Falcon and NanoSail-D, a setback to be sure, but keeping Elon Musk’s words in mind is probably good advice. In a letter to SpaceX employees, the company’s CEO noted that the Merlin 1C first stage engine worked flawlessly, the problem occurring in staging. The latter evokes the spectre of Cosmos 1, the Planetary Society’s mission, which also perished through booster failure. Musk went on to say:
As a precautionary measure to guard against the possibility of flight 3 not reaching orbit, SpaceX recently accepted a significant investment. Combined with our existing cash reserves, that ensures we will have more than sufficient funding on hand to continue launching Falcon 1 and develop Falcon 9 and Dragon. There should be absolutely zero question that SpaceX will prevail in reaching orbit and demonstrating reliable space transport. For my part, I will never give up and I mean never.
Musk means business, and that same attitude is surely felt through the community involved in solar sail activity, and in the larger community thinking about deep space missions at various space agencies, universities and private companies around the planet. Solar sails, leaving the propellant at home and hence able to significantly ramp up payload possibilities, are probably going to be key players in opening up the Solar System. Factor in beaming concepts from microwaves to lasers and you’re talking about a technology that makes sense and is workable under the laws of physics as presently understood. NanoSail-D never made it, but the more commercial possibilities we explore via companies like SpaceX, the sooner we’ll get the next sail into full space deployment.
by Paul Gilster | Aug 4, 2008 | Deep Sky Astronomy & Telescopes |
by Larry Klaes
It’s been a tough weekend, not only with the loss of the SpaceX Falcon booster but also the NanoSail-D sail experiment that flew aboard it. I’ll have more on the loss of the sail tomorrow, but this may be a good day to look back and reflect on some of the titans of astronomical history, including the Hale instrument whose views of the heavens gave so many of us early inspiration. Tau Zero journalist Larry Klaes has been pondering these matters, and offers us a look at some of the people and instruments that proved essential in changing our view of the universe.
Sixty years ago, on June 3, 1948, the most massive astronomical tool of the era was dedicated on Palomar Mountain near Pasadena, California. Known as the Hale Telescope, this instrument was much bigger than any telescope that had ever come before it. In its nearly three decades as the reigning largest telescope on Earth, the “Giant Eye” of the Palomar Observatory revealed new vistas of the heavens ranging from nearby worlds in our Solar System to the most distant galaxies billions of light years away.
The key to the scientific success of the Hale reflector telescope was its main mirror, which was made by Corning Glass Works (now known as Corning Incorporated) in Corning, New York, using their new Pyrex glass that was stronger and more flexible than other types of similar material. Such a material was necessary, as the initial mirror design was 200 inches (16.6 feet) across, 26 inches thick, and weighed 20 tons.
Image (click to enlarge): Palomar Observatory on what appears to be a fine night for viewing. Note Orion just above the trees. Credit: Scott Kardel.
Corning built two such mirrors at its glass factory in 1934 (the first one, a flawed piece later used for testing, is still on display in the company museum) and shipped it out to Pasadena on a slow-moving train. During its two-week journey across the country, huge crowds all along the delivery route came out to see the monster mirror. In Buffalo and several other major cities that the mirror passed through, the local police were called to control the throngs of people who massed around the special train.
A combination of the years it took to polish the mirror to its nearly flawless finish, the subsequent intervention of World War Two, and other factors kept the Hale Telescope from going into full operation until the year after its public dedication in 1948. The giant instrument retains yet another connection to Central New York, for it is now operated by a consortium of Cornell University, Caltech, and the Jet Propulsion Laboratory.
For an interesting look at the Hale Telescope, check out Palomar Skies. This site contains news, history, and beautiful images of Palomar Observatory written by Palomar public affairs coordinator Scott Kardel.
This year marks another important and much older telescope anniversary, one that essentially made the device housed inside that large white art deco dome on Palomar Mountain and every other telescope before and after it possible: The first definitive description (via a patent application) of a telescope.
The idea of magnifying objects using lenses and mirrors made of glass, quartz, and other substances goes back to ancient times. Reading glasses, or spectacles, were made during the Middle Ages to help people with poor or failing eyesight. One century before the telescope was “officially” recognized, Leonardo da Vinci described in his famous notebooks how a combination of lenses and mirrors would help one “to see the Moon enlarged… and …in order to observe the nature of the planets, open the roof and bring the image of a single planet onto the base of a concave mirror. The image of the planet reflected by the base will show the surface of the planet much magnified.” Whether da Vinci ever actually built and utilized what he wrote about in 1508 is a subject of dispute among historians.
There were others throughout Europe and the Middle East who also described what might be called a telescope during this era, but it was the Dutch spectacle maker named Hans Lippershey who applied for a patent on the telescope on September 25, 1608. Although Lippershey was not granted the patent, he was paid well for the invention by the Dutch government, which was focused on the telescope’s military and commercial applications.
Image: Hans Lippershey (1570-1619), the first to apply for a patent on a telescope design, and possibly the inventor of the first practical refracting instrument.
Within months of the announcement of this new observing instrument, telescopes were being made across Europe. Among the scientists of the era who were interested in the astronomical possibilities of the telescope, the most famous of them was Galileo Galilei.
Dissatisfied with the rather crude instruments made in his day, the Italian astronomer constructed his own telescopes, which he began using in 1609 to start a revolution in humanity’s understanding of the Cosmos. Being one of the first scientists to aim his telescopes at the heavens, Galileo saw that Earth’s Moon was not a smooth, polished sphere as once believed, but a cratered, mountainous place: An actual world much like our planet.
When Galileo observed the planet Jupiter in January of 1610, he saw four small “stars” moving around the gas giant globe. These points of light turned out to be the four largest of Jupiter’s moons – Io, Europa, Ganymede, and Callisto – which were later dubbed the Galilean satellites in the astronomer’s honor. Not only were the satellites the first bodies known to circle a world besides Earth, this discovery gave weight to the theory of Nicholas Copernicus, who had declared nearly two centuries earlier that Earth and the other worlds of the Solar System orbited the Sun, rather than everything in the Universe circling our planet, as was long believed.
Image: Galileo Galilei, in a portrait by Justus Sustermans (1597-1681), ca. 1639.
These innovations by Galileo and his contemporaries forever changed the way humanity looked at the Universe and our place in it. As telescope technology improved, astronomers gained even more evidence that our world was neither the center of existence nor the lowest of all places in the Cosmos, but just one of many worlds in a Universe full of stars and planets collected into immense cosmic islands called galaxies.
Although we now have instruments much larger than the Hale Telescope and sophisticated satellite telescopes exploring the heavens beyond the blurring confines of Earth’s atmosphere, the basic design and purpose of all telescopes has remained the same since a Dutch spectacle maker built the first models, an Italian scientist aimed his own optical tubes at the sky, and a far-seeing astronomer made some of the largest telescopes of the Twentieth Century possible. The role of these instruments in enhancing our understanding is nowhere near the end of its journey.
by Paul Gilster | Aug 2, 2008 | Exotic Physics |
What could be causing gamma-ray photons to be streaming from the galactic core with a precise energy of 511 keV (8 X 10-14 joules)? It’s an interesting question, one tackled by Ian O’Neill on his astroENGINE site, as posted by 21st Century Waves in this week’s Carnival of Space. O’Neill notes the defining nature of this energy level, which turns out to be the exact rest mass energy of a positron, the antimatter equivalent of an electron. That fact suggests the annihilation of positrons in the galactic center, but what’s causing it?
The usual suspects just don’t fit, as O’Neill is quick to note:
The first thing that comes to mind is a gamma-ray burst, produced when a massive star dies and collapses as a supernova. But this is short-lived and not sustained. How about the supermassive black hole sitting in the middle of the Milky Way’s galactic nucleus? This theory was recently discussed on Astroengine, but the production of antimatter (i.e. positrons) is more of a slow leak than anything substantial, certainly not of the scale that is being measured. As we are dealing with gamma-rays of the exact rest mass energy as a positron, so we know that the source is some kind of positron annihillation. What could possibly be doing this?
Seong Chan Park (Seoul National University) and team may have an answer in their speculation about the existence of a new particle called the millicharged fermion. Now we’re in dark matter territory — the millicharged fermion has a history running back twenty years in dark-matter speculations. And the mechanism may work, for the particle is calculated to decay into an electron and positron, leading to quick annihilation. Moreover, the tiny charge of the millicharged fermion would make it all but transparent to detection efforts. Dark indeed.
Intriguing work, and good reason to keep following ESA’s INTEGRAL mission, launched in 2002, which focuses on gamma-ray sources (absorbed by the atmosphere, gamma-rays must be studied from space). But don’t assume gamma-ray bursts (GRBs) are the cause of the unusual emissions. They’re short-lived and can’t account for the renewable nature of what INTEGRAL has found flowing from the galactic bulge. As with dark matter speculation itself, the galactic core turns out to be a good place for what O’Neill calls “…new particle physics and some lateral thinking…”
by Paul Gilster | Aug 1, 2008 | Astrobiology and SETI |
Without the explosions of supernovae, the heavy elements so essential to life itself would be unavailable, and stars would lack the raw materials to form planets. Thus Carl Sagan’s famous “We are star-stuff” quotation, an idea validated by our extrasolar studies, which allow us to correlate the presence of planets with the existence of heavy elements in their stars. Much remains to be done here, but stars with higher metallicity and more heavy elements do appear more likely to have planets.
Volker Bromm (now at the University of Texas) puts it this way:
“We’re now just beginning to investigate the metallicity threshold for planet formation, so it’s hard to say when exactly the window for life opened. But clearly, we’re fortunate that the metallicity of the matter that birthed our solar system was high enough for the Earth to form. We owe our existence in a very direct way to all the stars whose life and death preceded the formation of our Sun. And this process began right after the Big Bang with the very first stars. As the universe evolved, it progressively seeded itself with all the heavy elements necessary for planets and life to form. Thus, the evolution of the universe was a step-by-step process that resulted in a stable G-2 star capable of sustaining life. A star we call the Sun.”
While at the Harvard-Smithsonian Center for Astrophysics, Bromm worked with Lars Hernquist and Naoki Yoshida (now at Nagoya University) on simulations of the first supernova explosions, studies designed to plot their evolution and the subsequent birth of stars like the Sun. The latter two, working with Kazuyuki Omukai (National Astronomical Observatory of Japan) have now released simulations offering a still more precise picture of the earliest stars, work that incorporates dark matter in the mix. The result: A protostar with one percent of the Sun’s mass would evolve into a massive star a hundred times as massive as Sol, one that would burn for no more than a million years and synthesize heavy elements.
All of this gets us into the spread of heavy elements not simply in later generations of stars but relatively soon after the Big Bang. Indeed, Bromm’s earlier work with Avi Loeb had determined that a first-generation supernova could produce the heavy elements needed to allow the first Sun-like stars to form. The upshot is that many second-generation stars would have had the size, mass and temperature of the Sun, but with such low abundances of metals that they would have been unable to form rocky planets. For that, we need subsequent generations of stars and a more metal-rich interstellar medium. But over what time frame?
Image: The first primordial stars began as tiny seeds that grew rapidly into stars one hundred times the mass of our own Sun. Seen here in this artist impression, swirling clouds of hydrogen and helium gasses are illuminated by the first starlight to shine in the Universe. In the lower portion of the artwork, a supernova explodes ejecting heavier elements that will someday be incorporated into new stars and planets. Credit: David A. Aguilar, CfA
From an astrobiological perspective, it would be fascinating to learn how quickly stars that could support planets and life might have formed. Here Fermi again raises his head — If the universe might have supported life billions of years ago (Charles Lineweaver has written fascinatingly on this), then shouldn’t there be civilizations billions of years older than our own? It’s an elegant supposition, but what Yoshida and team have accomplished thus far is but to simulate a protostar’s birth, one whose further growth will require more intensive computational resources as the simulation progresses toward the supernova stage.
Even so, says Lars Hernquist, “This general picture of star formation, and the ability to compare how stellar objects form in different time periods and regions of the universe, will eventually allow investigation in the origins of life and planets.” And that’s something anyone with a yen to understand life’s place in the universe will want to keep an eye on. The paper is Yoshida, Omukai and Hernquist, “Protostar Formation in the Early Universe,” Science Vol. 321, No. 5889 (August 1, 2008), pp. 669-671 (abstract).
