The next space shuttle mission STS-129, slated to launch next Monday Nov. 16, is a “spare parts and stock-up” mission. And the needed extra parts and supplies delivered to the International Space Station by Atlantis will mean spare years on the station’s life once the space shuttle fleet is retired. The mission is a landmark of sorts — not sure if it is a good landmark or bad — but STS-129 is scheduled to be the last space shuttle crew rotation flight. From here on out, crew rotation will be done by the Soyuz and any future commercial vehicle that may come online. Besides the crew, a payload of spiders and butterfly larvae will be on board Atlantis for an experiment that will be monitored by thousands of K-12 students across US. Find out more about the flight with a video preview of the mission, below.
STS-129 will be commanded by Charlie Hobaugh and piloted by Barry Wilmore. Mission Specialists are Robert Satcher Jr., Mike Foreman, Randy Bresnik and Leland Melvin. Wilmore, Satcher and Bresnik will be making their first trips to space. The mission will return station crew member Nicole Stott to Earth.
The crew will deliver two control moment gyroscopes and other equipment, plus the EXPRESS Logistics Carrier 1 and 2 to the station. The mission will feature three spacewalks.
White dwarfs are strange stars, but researchers recently discovered two of the strangest yet. However, these two oddballs are a missing link of sorts, between massive stars that end their lives as supernovae and small to medium sized stars that become white dwarfs. Somehow, these two once-massive stars avoided the core collapse of a supernova, and are the only two white dwarfs known to have oxygen-rich atmospheres. These so-called massive white dwarfs have been predicted, but never before observed.
The stars, named SDSS 0922+2928 and SDSS 1102+2054 are 400 and 220 light years from Earth. They are both remnants of massive stars that are at the end of their stellar evolution having consumed all the material they had available for nuclear fusion.
The low levels of carbon visible in their spectra indicate the stars have shed part of their outer layers and burned the carbon contained in their cores.
“These surface abundances of oxygen imply that these are white dwarfs displaying their bare oxygen-neon cores, and that they may have descended from the most massive progenitors stars in that class,” said astrophysicist Dr. Boris Gänsicke from the University of Warwick, lead author on a paper appearing in this week’s edition of Science Express. Dr. Boris Gänsicke from the department of physics at the University of Warwick.
Gänsicke told Universe Today that he and his team didn’t start out specifically looking for these previously theoretical stars. “I’ve been working with our research student Jonathan Girven on several projects on white dwarfs, and we came across a range of unusual looking objects — some we are still puzzling what they are. From a theoretical perspective, I was wondering if white dwarfs with oxygen-rich atmospheres exist, and combining both angles, we developed a specific search for these stars.”
In a search of Sloan Digital Sky Survey data, the astrophysicists did indeed discover two white dwarfs with large atmospheric oxygen abundances.
Almost all white dwarfs have hydrogen and/or helium envelopes that, while low in mass, are sufficiently thick to shield the core from direct view. Theoretical models predicted that if stars around 7 – 10 times the mass of our own Sun don’t end their lives as supernovae, the other option is that they will consume all of their hydrogen, helium and carbon, and end their lives as white dwarfs with very oxygen-rich cores.
Astrophysicists could then detect an extremely oxygen-rich spectrum from the surface of the white dwarf.
Most stellar models producing white dwarfs with such oxygen and neon cores also predict that a sufficiently thick carbon-rich layer should surround the core and avoid upward diffusion of large amounts of oxygen.
However, calculations also show that the thickness of this layer decreases the closer the progenitor star is to upper mass limit for stars ending their lives as white dwarfs. Hence one possibility for the formation of SDSS 0922+2928 and SDSS 1102+2054 is that they descended from the most massive stars avoiding core-collapse, in which case they would be expected to be very massive themselves. However current data is insufficient to provide any unambiguous measure of the masses of these two unusual stars.
What is the future for these massive white dwarfs? Gänsicke said the two stars will evolve very slowly. “Given that they are burnt-out stellar cores that do no longer undergo nuclear fusion, their destiny is to continue cooling and fading. This will be a very slow process, and any noticeable change in their appearance will take 10s to 100s million years.”
Lead image caption: Sloan Digital Sky Survey spectroscopy of this inconspicuous blue object — SDSS1102+2054 — reveals it to be an extremely rare stellar remnant: a white dwarf with an oxygen-rich atmosphere
Upcoming commercial space flights are no longer only about rich, adventure-seeking space tourists. Researchers hope to capitalize on the prospect of quick, low-cost and frequent access to the micro-gravity environment of sub-orbital space. “We’ve got these great vehicles coming online and most of the discussion about them so far have centered on the tourism market,” said Erika Wagner, member of SARG – the Suborbital Applications Researcher Group. “As researchers we felt this was a fantastic opportunity to do both science and education, as well.”
SARG was chartered by the Commercial Spaceflight Federation, and consists of around a dozen scientists and researchers from across the spectrum of the different sciences. Led by Alan Stern who formerly headed NASA’s science directorate, the group has sponsored three different workshops for scientists in Boston, Houston and Los Angeles, with another upcoming in Boulder Colorado (Feb. 18-20, 2010). “We want to inform researchers on this opportunity,” Wagner told Universe Today,” and find out how they want to use the vehicles and any constraints they might have, and feed that back to the vehicle designers and flight providers.”
About a year ago, SARG started surveying scientists, as well as getting the word out to NASA and other funding agencies that scientists were excited about sub-orbital space. “We’ve started to build some momentum now with the Commercial Reusable Suborbital Research program,” Wagner said, “and NASA has put up $2.6 million to support suborbital research in 2010. We’re putting everything in place to get everything structured to make this a viable research platform.” Erika Wagner at the International Symposium for Personal and Commercial Spaceflight. credit: ISPCS
Sub-orbital science appears to be a win-win situation for both scientists and the nascent commercial spaceflight companies. For researchers, the flights represent cheaper and more frequent access to space than anything NASA can provide with the space shuttle, parabolic flights or sounding rockets. For companies like Armadillo Aerospace, Blue Origin, Masten Space Systems, Virgin Galactic, and XCOR, adding science to their payloads represents the possibility of an additional $100 million a year in fares — roughly equivalent to the fares that would be paid out by 500 passengers.
Wagner said this new sub-orbital realm represents an entire new dimension for scientists. “The researchers hadn’t thought about it much before,” she said. “Mostly the research being done now is on the space shuttle and space station and is geared towards long duration flights. But the idea of how we use 3 or 4 minutes of microgravity is a real paradigm shift.”
“They would be able to do anything that requires being above the atmosphere but doesn’t require a Hubble Space Telescope,” Wagner continued,” or planetary science measurements, or atmospheric measurements as you go up and down. There’s a whole area that is called the “ignorosphere” – the part of the atmosphere that is too thin for planes to fly in but too thick for satellites to fly through, which has been pretty much ignored by the scientific community. But the suborbital vehicles go right through it.”
Then there’s basic fluids research- how do bubbles and fluids interact, which has implications for designing spacecraft engines –, particulates research, studying how the human body adapts to space, and other medical investigations.
Trajectory of the Vomit Comet, the KC 135 flights. Credit: NASA
“Several years ago researchers developed techniques for CPR in microgravity in case they ever need it on the space station,” Wagner said. “They tested in on the Vomit Comet, (parabolic flights) and you have only 20-30 second bursts, and it’s really hard to develop procedures for that, or especially for minor surgery or emergency procedures in that amount of time. 3-4 minutes gives you an opportunity to practice them and do training.”
Wagner, who works in life science research at MIT said what she finds most exciting is that sub-orbital opens up much more broadly the range of people that can be sent into space.
“Of the 450 or so astronauts that have been to space, all have been between 25-50 year of age, been very healthy and well trained,” she said. “Soon, there will be thousands of people who will be going into space which means we can begin to study the differences between men and women, young and old, and open it up to people who never would have been eligible to fly with NASA. Then we could study the effect of microgravity for someone who has a chronic heart condition or diabetes, or people who are on medication. For me that is the most interesting.”
A recent market analysis predicts there could be a demand for 13,000 passengers a year for commercial spaceflight, and SARG predicts there could be demand for over 1,000 flights a year for researchers.
“Down the line, we see 1,000 flights a year,” Wagner said.” Right now we have just a small handful of vehicle developers that have actual hardware in hand, and double that that are in earlier stages. Virgin Galactic is talking about one flight a day or several flights a day, so eventually we can see reaching that flight volume but it will be probably be several years.” Space science on the space station. Credit: NASA
Early flights could include small payloads bolted to a rack or strapped down in the back of the vehicle, as well as passive data collection. “But once tourists start flying we can say, ‘Hey, would you mind if we took your blood pressure before the flight or would you be willing to wear an EKG harness?'” Wagner said, “– some easy things, which also might makes it more exciting for the tourists who can say they were part of an experiment on their flight.”
Later on, Wagner predicts researchers will be able to fly themselves to do hands-on science. “Does this mean that we are going to fly every scientist with his or her own payload or are there going to be a new class of payload specialists that emerge as commercial operators for science?” said Wagner. “It will be interesting to see how this develops.”
There’s plenty of potential for education, too. “Perhaps we can engage students in the work that is going on, and fly small payloads for students and actually allow them to get involved in science again,” Wagner said. “It’s been awhile since NASA has flown student payloads on the space shuttle, and these vehicles with higher flight frequency and lower costs are just custom made for getting students engaged. If commercial vehicles are flying every week, suddenly you can go end-to-end in a senior design project or have a master’s thesis where you’ve used the space environment for testing. Or you can design things that might fit in a tourist’s pocket, such as handheld sensors or iPhone apps and start to engage K-12 kids.” Alan Stern at ISPCS. Credit: ISPCS
Wagner and Stern recently spoke at a panel session at the International Symposium for Personal and Commercial Spaceflight in Las Cruces, N.M, where Wagner said the question she was asked most often was how suborbital science can contribute to the goal of humans living and working in space on a larger basis.
“For me it’s about opening the doors to the general population,” she said. “Right now if we were going to talk about sending people to Mars, it would be government astronauts — well selected, very fit, very healthy individuals. But if we are going to talk about a longer term vision of the future, where we open up that bottle and send the average Joe and Jane, now we can start to understand what might happen to you or I in space and what we need to do to support the general population – all ages, all genders, all nationalities, all health statutes. The opportunity to blow that wide open is really great.”
NASA is now joining in to combat the 2012 nonsense. Don Yeomans, manager of NASA’s Near Earth Object office has produced a video and written an article, providing the scientific realities surrounding the celestial happenings of 2012. Yeomans has done a wonderful job explaining everything that is and isn’t going to happen in 2012, and we’re happy to add his work to our collection of 2012 debunking articles. Continue reading “2012: NASA’s Scientific Reality Check”
In the microwave in your kitchen, food gets cooked (or heated) by absorbing microwave radiation, which is electromagnetic radiation between the (far) infrared and the radio, in the electromagnetic spectrum. The microwave region is rather broad, and somewhat vague, because the overlap with the radio (at around 1 meter, or 300 MHz) is not clear-cut, nor is the overlap with the sub-millimeter (or terahertz) region (at around 1 mm, or 300 GHz).
In astronomy, by far the most well-known aspect of microwave radiation is the cosmic microwave background (CMB), which has a near-perfect blackbody spectrum, of 2.73 K; this peaks at around 1.9 mm (160 GHz – the peak differs when measured by wavelength, from when measured by frequency).
The workhorse detector, in microwave astronomy (and much of radio astronomy, in general), is the radiometer, whose operation is described in considerable detail on this NRAO (National Radio Astronomy Observatory) webpage. The particular kind of radiometer which Penzias and Wilson used in their discovery of the CMB (at 7.35 cm, well away from the CMB peak) was a Dicke radiometer, designed by Robert Dicke (to search for the CMB!). And it was six differential microwave radiometers aboard the Cosmic Background Explorer (COBE) which first detected the CMB anisotropy, firmly establishing the CMB as the highly redshifted surface of last scattering (when baryonic matter and photons decoupled).
The microwave region, especially the short (millimeter) wavelength end, is a rich region for astrophysics, allowing the study of galaxy formation and evolution, stellar and planetary system birth, the composition of solar system body atmospheres, in addition to the CMB. There are already several observatories – many consortia – active in these fields; for example CARMA (Combined Array for Research in Millimeter-wave Astronomy), and ALMA (Atacama Large Millimeter/submillimeter Array) … astronomers just LOVE acronyms! (and no, that is not an acronym).
A new kind of microwave astronomical observatory has recently begun making obserations, the Allen Telescope Array, which provides instantaneous frequency coverage from 500 MHz to 11 GHz (among many other firsts). In many ways this serves as a technology demonstrator for the much more ambitious Square Kilometre Array.
[/caption]
Nereid is the name given to the third largest of Neptune’s moons, and the second to have been discovered … by veteran outer solar system astronomer, Gerard P. Kuiper (guess who the Kuiper Belt is named after!), in 1949. Prior to Voyager 2’s arrival, it was the last moon of Neptune to be discovered.
In keeping with the nautical theme (Neptune, Roman god of the sea; Triton, Greek sea god, son of Poseidon), Nereid is named after the fifty sea nymphs, daughters of Nereus and Doris, in Greek mythology … the nautical theme continues with the names of the other 11 moons of Neptune, Naiad (one kind of nymph, Greek mythology; not a Nereid), Thalassa (daughter of Aether and Hemera, Greek mythology; also Greek for ‘sea’), Despina (nymph, daughter of Poseidon and Demeter (Greek); not a Nereid), Galatea (one of the Nereids), Larissa (Poseidon’s lover; Poseidon is the Greek Neptune), Proteus (also a sea god in Greek mythology; Proteus is the Neptune’s second largest moon), Halimede (one of the Nereids), Sao (also one of the Nereids), Laomedeia (guess … yep, another of the Nereids), Psamathe (ditto), and Neso (ditto, all over again).
Almost everything we know about Nereid comes from the images Voyager 2 took of it (83), between 20 April and 19 August, 1989; its closest approach was approximately 4.7 million km.
Nereid’s highly eccentric orbit (eccentricity 0.75, the highest of any solar system moon) takes it from 1.37 million km from Neptune to 9.66 million km (average 5.51 million km); unlike Triton, and like the other inner moons, Nereid’s orbit is prograde. This suggests that it may be a captured Kuiper Belt object, or that its orbit was substantially perturbed when Triton was captured.
For an irregular moon, Nereid is rather large (radius approx 170 km). Its spectrum and color (grey) are quite different from those of other outer solar system bodies (e.g. Chiron), which suggests that it may have formed around Neptune.
The number of multiverses the human brain could distinguish. Credit: Linde and Vanchurin
[/caption]
To some extent, ‘parallel universe’ is self-referential … there are parallel meanings of the very term! The two most often found in science-based websites (like Universe Today) are multi-verse, or multiverse (the universe we can see is but one of many universes), and the many-worlds interpretation of quantum physics (most often associated with Hugh Everett).
Cosmologist Max Tegmark (currently at MIT) has a neat classification scheme for pigeon-holing most parallel universe ideas that have at least some relationship to physics (as we know it today).
The most straight-forward kind of parallel universe(s) is one(s) just like the one we can see, but beyond the (cosmic) horizon … space is flat, and infinite, and the laws of physics (as we know them today) are the same, everywhere.
Similar, but different in some key ways, are parallel universes which developed out of inflation bubbles; these have the same (or very similar) physics to what applies in the universe we can see, except that the initial values (e.g. fine-structure constant) and perhaps number of dimensions may differ. The Inflationary Multiverse ideas of Standford University’s Andrei Linde are perhaps the best known example of this type. Parallel universes at this level tie in naturally to the (strong) anthropic principle.
Tegmark’s third class (he calls them Levels; this is Level 3) is the many-worlds of quantum physics. I’m sure you, dear reader, are familiar with poor old Schrödinger’s cat, whose half-alive and half-dead status is … troubling. In the many-worlds interpretation, the universe splits into two equal – and parallel – parts; in one, the radioactive material decays, and the cat dies; in the other, it does not, and the cat lives.
Level 4 contains truly weird parallel universes, ones which differ from the others by having fundamentally different laws of physics.
Operating somewhat in parallel are two other parallel universe concepts, cyclic universes (the parallelism is in time), and brane cosmology (a fallout from M-theory, in which the universe we can see is confined to just one brane, but interacts with other universes via gravity, which is not restricted to ‘our’ brane).
As you might expect, much, if not most, of this has been attacked for not being science (for example, how could you ever falsify any of these ideas?), but at least for some parallel universe ideas, observational tests may be possible. Perhaps the best known such test is the WMAP cold spot … one claim is that this is the imprint on ‘our’ universe of a parallel universe, via quantum entanglement (the most recent analyses, however, suggest that the cold spot is not qualitatively different from others, which have more prosaic explanations What! No Parallel Universe? Cosmic Cold Spot Just Data Artifact is a Universe Today story on just this).
It’s time once again for another Where In The Universe Challenge. Test your visual knowledge of the cosmos by naming where in the Universe this image was taken and give yourself extra points if you can name the spacecraft responsible for this picture. Post your guesses in the comments section, and check back on Thursday at this same post to find the answer. To make this challenge fun for everyone, please don’t include links or extensive explanations to the answer in your comments. Good luck!
UPDATE: The answer has now been posted below.
Also, if you have suggestions for a future WITU Challenge, email me.
Yes, this is us, the planet Earth as seen by Voyager 1 from 3.7 billion miles (6 billion kilometers) away. I’ll let Carl Sagan explain it: (from an address he gave in 1996 and the basis for his essay and book, “Pale Blue Dot.”)
“Look again at that dot. That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every “superstar,” every “supreme leader,” every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.
The Earth is a very small stage in a vast cosmic arena. Think of the rivers of blood spilled by all those generals and emperors so that, in glory and triumph, they could become the momentary masters of a fraction of a dot. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner, how frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds.
Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.
The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment the Earth is where we make our stand.
It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we’ve ever known.”
Artist’s impression of a baby star still surrounded by a protoplanetary disc in which planets are forming. Credit: ESO
For decades, astronomers have known our Sun contains a low amount of lithium, while other solar-like stars actually have more. But they didn’t know why. By looking at stars similar to the Sun to study this anomaly, scientists have now discovered of a trend: the majority of stars hosting planets possess less than 1% of the amount of lithium shown by most of the other stars. “The explanation of this 60 year-long puzzle is for us rather simple,” said Garik Israelian, lead author on a paper appearing in this week’s edition of Nature. “The Sun lacks lithium because it has planets.”
This finding sheds light not only on the lack of lithium in our star, but also provides astronomers with a very efficient way of finding stars with planetary systems.
Isrealian and his team took a census of 500 stars, 70 of which are known to host planets, and in particular looked at Sun-like stars, almost a quarter of the whole sample. Using ESO’s HARPS spectrograph, a team of astronomers has found that Sun-like stars that host planets have destroyed their lithium much more efficiently than “planet-free” stars.
“For almost 10 years we have tried to find out what distinguishes stars with planetary systems from their barren cousins,” Israelian said. “We now have found that the amount of lithium in Sun-like stars depends on whether or not they have planets.”
These stars have been “very efficient at destroying the lithium they inherited at birth,” said team member Nuno Santos. “Using our unique, large sample, we can also prove that the reason for this lithium reduction is not related to any other property of the star, such as its age.”
Unlike most other elements lighter than iron, the light nuclei of lithium, beryllium and boron are not produced in significant amounts in stars. Instead, it is thought that lithium, composed of just three protons and four neutrons, was mainly produced just after the Big Bang, 13.7 billion years ago. Most stars will thus have the same amount of lithium, unless this element has been destroyed inside the star.
This result also provides the astronomers with a new, cost-effective way to search for planetary systems: by checking the amount of lithium present in a star astronomers can decide which stars are worthy of further significant observing efforts.
Now that a link between the presence of planets and curiously low levels of lithium has been established, the physical mechanism behind it has to be investigated. “There are several ways in which a planet can disturb the internal motions of matter in its host star, thereby rearrange the distribution of the various chemical elements and possibly cause the destruction of lithium,” said co-author Michael Mayor. ” It is now up to the theoreticians to figure out which one is the most likely to happen.”
Herschel in 3-D. Credit: Nathanial Burton-Bradford.
[/caption]
Sometimes, in astronomy, the name of a thing describes it well; a parabolic mirror is, indeed, a mirror which has the shape of a parabola (an example of a name that does not describe itself well? How about Mare Nectaris, “Sea of Nectar”!). Actually, it’s a circular paraboloid, the 3D shape you get by rotating a parabola (which is 2D) around its axis.
The main part of the standard astronomical reflecting telescope – the primary mirror – is a parabolic mirror. So too is the dish of most radio telescopes, from the Lovell telescope at Jodrell Bank, to the telescopes in the Very Large Array; note that the dish in the Arecibo Observatory is not a parabolic mirror (it’s a spherical one). Focusing x-ray telescopes, such as Chandra and XMM-Newton, also use nested parabolic mirrors … followed by nested hyperbolic mirrors.
Why a parabolic shape? Because mirrors of this shape reflect the light (UV, IR, microwaves, radio) from distant objects onto a point, the focus of the parabola. This was known in ancient Greece, but the first telescope to incorporate a parabolic mirror wasn’t made until 1673 (by Robert Hooke, based on a design by James Gregory; the reflecting telescope Newton built used a spherical mirror). Parabolic mirrors do not suffer from spherical aberration (spherical mirrors cannot focus all incoming, on-axis, light onto a point), nor chromatic aberration (single lens refracting telescopes focus light of different colors at different points), so are the best kind of primary mirror for a simple telescope (however, off-axis sources will suffer from coma).
The Metropolitan State College of Denver has a cool animation of how a parabolic mirror focuses a plane wave train onto a point (the focus).
