Space and astronomy news
David McCormack took this picture of Venus, Mercury and Saturn during their recent conjunction from Sunbury, Australia.
Do you have photos you’d like to share? Post them to the Universe Today astrophotography forum or email them to me directly, and I might feature one in Universe Today.
Deep Impact took this image of its own impactor drifting away from the spacecraft. Image credit: NASA/JPL. Click to enlarge.
One hundred and seventy-one days into its 172-day journey to comet Tempel 1, NASA’s Deep Impact spacecraft successfully released its impactor at 11:07 p.m. Saturday, Pacific Daylight Time (2:07 a.m. Sunday, Eastern Daylight Time).
At release, the impactor was about 880,000 kilometers (547,000 miles) away from its quarry. The separation of flyby spacecraft and the washing-machine-sized, copper-fortified impactor is one in a series of important mission milestones that will cap off with a planned encounter with the comet at 10:52 p.m. Sunday, PDT (1:52 a.m. on July 4, EDT).
Six hours prior to impactor release, the Deep Impact spacecraft successfully performed its fourth trajectory correction maneuver. The 30-second burn changed the spacecraft’s velocity by about one kilometer per hour (less than one mile per hour). The goal of the burn is to place the impactor as close as possible to the direct path of onrushing comet Tempel 1.
Soon after the trajectory maneuver was completed, the impactor engineers began the final steps that would lead to it being ready for free flight. The plan culminated with activation of the impactor’s batteries at 10:12 p.m., PDT (1:12 a.m. Sunday, EDT). Deep Impact’s impactor has no solar cells; the vehicle’s batteries are expected to provide all the power required for its short day-long life.
In order to release the impactor, separation pyros fired allowing a spring to uncoil and separate the two spacecraft at a speed of about 35 centimeters per second (0.78 mile per hour).
With Tempel 1 closing the distance between it and impactor at about 10 kilometers (6 miles) per second, there is little time for mission controllers to admire their work. Twelve minutes after impactor release the flyby began a 14-minute long divert burn that slowed its velocity relative to the impactor by 102 meters per second (227 miles per hour), moving it out of the path of the onrushing comet nucleus and setting the stage for a ringside seat of celestial fireworks to come less than 24 hours later.
Deep Impact mission controllers have confirmed the impactor’s S-band antenna is talking to the flyby spacecraft. All impactor data including the expected remarkable images of its final dive into the comet’s nucleus will be transmitted to the flyby craft — which will then downlink them to Deep Space Network antennas that are listening 134 million kilometers (83 million miles) away.
While all is going as expected on the Deep Impact spacecraft the comet itself is putting on something of a show. The 14-kilometer-long (8.7-mile-long) comet Tempel 1 displayed another cometary outburst on July 2 at 1:34 a.m. PDT (4:34 a.m.EDT) when a massive, short-lived blast of ice or other particles escaped from inside the comet’s nucleus and temporarily expanded the size and reflectivity of the cloud of dust and gas (coma) that surrounds it. The July 2 outburst is the fourth observed in the past three weeks.
Three of the outbursts appear to have originated from the same area on the surface of the nucleus but they do not occur every time that that area faces the Sun.
“The comet is definitely full of surprises so far and probably has a few more in store for us,” said Deep Impact Project Manager Rick Grammier of NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “None of this overly concerns us nor has it forced us to modify our nominal mission plan.”
Information and images from a camera aboard Deep Impact’s impactor and flyby spacecraft can be watched in near-real time at http://www.nasa.gov/deepimpact.
For additional information about Deep Impact on the Internet, visit NASA Deep Impact.
Original Source: NASA News Release
Hi folks, it’s Canada Day today here, so I’m taking the day off . Universe Today will be back on Monday with plenty of fresh space news.
Fraser Cain
Publisher
Universe Today
How many times have I been to space? Well, I lost count at, oh, none. So I, and nearly every other human being on Earth can’t compare with Story Musgrave, a legendary NASA astronaut who flew on the space shuttle six times, including leading the team that fixed the Hubble Space Telescope’s vision in 1993. He’s the subject of a recent biography called Story: the Way of Water, and has a new CD called Cosmic Fireflies, which sets his space inspired poetry to music. Story speaks to me from his home in Florida.
Continue reading “Podcast: Interview with Story Musgrave”
Computer illustration of a potential antimatter drive. Image credit: Positronics Research LLC. Click to enlarge.
We all played the game as children – “leapfrog” involved one child squatting on all fours while a second placed their hands on the first’s shoulders. Braced against the pull of gravity, the standing child bends at the legs deeply then thrusts up and over the top of the first. The result? The second child now squats and the another froglike leap follows in turn. Not the most efficient way to get to the swing set – but a lot of fun in the right company!
Leapfrogging however is not the same as ‘bootstrapping’. While bootstrapping, a single player bends and grabs the leather loops on the outside of both boots. The player then makes a tremendous exertion upward with the arms. Leapfrogging works – bootstrapping doesn’t, it just can’t be done without hopping – an entirely different thing altogether.
The NASA Institute for Advanced Concepts (NIAC) believes in leapfrogging – no not on the playground but in aerospace. From the institutes own website: “NIAC encourages proposers to think decades into the future in pursuit of concepts that will “leapfrog” the evolution of current aerospace systems.” NIAC is looking for a few good ideas and is willing to support them with six-month-long seed grants to test feasibility before serious research and development funds – available from NASA and elsewhere – are allocated. Hopefully such seeds are allowed to germinate and future investment grows them to maturity.
NIAC wants to separate out leapfrogging from bootstrapping, however. One works and the other makes no sense whatsoever. According to NIAC, the positron drive could lead to a giant leap forward in the way we travel throughout the solar system and beyond. There’s probably no bootstrapping about it.
Consider the positron – mirror twin of the electron – like human twins, a very rare thing. Unlike human twins, a positron is unlikely to survive the birth process. Why? Because positrons and their siblings – electrons – find each other irresistible and quickly annihilate in a burst of soft gamma rays. But that burst, under controlled circumstances, can be converted into any form of ‘work’ you might want to do.
Need light? Mix a positron and an electron then irradiate a gas to incandescence. Need electricity? Mix another pair and irradiate a metal strip. Need thrust? Shoot those gamma rays into a propellant, heat it to outlandishly high temperatures and push the propellant out the back of the rocket. Or, shoot those gamma rays into tungsten plates in a stream of air, heat that air and jettison it out the back of an aircraft.
Imagine having a supply of positrons – what could you do with them? According to Gerald A. Smith, Principle Investigator for Positronics Research, LLC of Sante Fe, New Mexico you could go just about anywhere, “the energy density of antimatter is ten orders of magnitude greater than chemical and three orders of magnitude greater than nuclear fission or fusion energy.”
And what does this mean in terms of propulsion? “Less weight, far, far, far less weight.”
Using chemically based propulsion systems, 55 percent of the weight associated with the Huygens-Cassini probe sent to explore Saturn was found in the probe’s fuel and oxidizer tanks. Meanwhile to hurl the probes 5650 kg of weight beyond the Earth required a launch vehicle weighing some 180 times that of fully-fueled Cassini-Huygens itself (1,032,350 kgs).
Using Dr. Smith’s numbers alone – and only considering the maneuvering thrust required for Cassini-Huygens using positron-electron annihilation, the 3100 kgs of chemical propellant burdening the original 1997 probe could be reduced to a mere 310 micrograms of electrons and positrons – less matter than that found in a single atomized drop of morning mist. And with this reduction in mass the total launch weight from Canaveral to Saturn could easily be reduced by a factor of two.
But positron-electron annihilation is like having plenty of air but absolutely no gasoline ? your car won?t get far on oxygen alone. Electrons are everywhere, while positrons are not naturally available on Earth. In fact where they do occur – near black hole event horizons or for short periods of time after high energy particles enter the Earth’s atmosphere – they soon find one of those ubiquitous electrons and go photonic. For this reason you have to make your own.
Enter the particle accelerator
Companies such as Positronics Research, headed up by Dr. Smith, are working on technologies inherent in the use of particle accelerators – like the Stanford Linear Accelerator (SLAC) located in Menlo Park, California. Particle accelerators create positrons using electron-positron pair-production techniques. This is done by smashing a relativistically accelerated electron beam into a dense tungsten target. The electron beam is then converted into high energy photons which move through the tungsten and turn into matched sets of electrons and positrons. The problem before Dr. Smith and others creating positrons is easier than trapping, storing, transporting, and using them effectively.
Meanwhile during pair-production, all you’ve really done is packed a whole lot of earth-bound energy into extremely small amounts of highly volatile – but extremely light-weight – fuel. That process itself is extremely inefficient and introduces major technical challenges related to accumulating enough anti-particles to power a spacecraft capable of journeying into the Great Beyond at velocities making large space probe – and human spacetravel – possible. How is all this likely to play out?
According to Dr. Smith, “for many years physicists have squeezed positrons out of the tungsten targets by colliding the positrons with matter, slowing them down by a thousand or so to use in high resolution microscopes. This process is horribly inefficient; only one millionth of the positrons survive. For space travel we need to increase the slowing down efficiency by at least a factor of one thousand. After four years of hard work with electromagnetic traps in our labs, we are preparing to capture and cool five trillion positrons per second in the next few years. Our long-range goals are five quad-trillion positrons per second. At this rate we could fuel up for our first positron-fueled flight into space in a matter of hours.”
While it is true that a positron-annihilation engine also requires propellent (typically in the form of compressed hydrogen gas), the amount of propellant itself is reduced to almost 10 percent of that required by a conventional rocket – since no oxidizer is needed to react with the fuel. Meanwhile, future craft may actually be able to scoop propellant up from the solar wind and interstellar medium. This should also lead to a significant reduction in the launch weight of such spacecraft.
Written by Jeff Barbour
One of the meteorites analyzed to help pinpoint the age of Milky Way. Image credit: Nicolas Dauphas, University of Chicago. Click to enlarge.
The University of Chicago?s Nicolas Dauphas has developed a new way to calculate the age of the Milky Way that is free of the unvalidated assumptions that have plagued previous methods. Dauphas? method, which he reports in the June 29 issue of the journal Nature, can now be used to tackle other mysteries of the cosmos that have remained unsolved for decades.
?Age determinations are crucial to a fundamental understanding of the universe,? said Thomas Rauscher, an assistant professor of physics and astronomy at the University of Basel in Switzerland. ?The wide range of implications is what makes Nicolas? work so exciting and important.?
Dauphas, an Assistant Professor in Geophysical Sciences, operates the Origins Laboratory at the University of Chicago. His wide-ranging interests include the origins of Earth?s atmosphere, the oldest rocks that may contain evidence for life on Earth and what meteorites reveal about the formation of the solar system.
In his latest work, Dauphas has honed the accuracy of the cosmic clock by comparing the decay of two long-lived radioactive elements, uranium-238 and thorium-232. According to Dauphas? new method, the age of the Milky Way is approximately 14.5 billion years, plus or minus more than 2 billion years.
That age generally agrees with the estimate of 12.2 billion years?nearly as old as the universe itself? as determined by previously existing methods. Dauphas? finding verifies what was already suspected, despite the drawbacks of existing methods: ?After the big bang, it did not take much time for large structures to form, including our Milky Way galaxy,? he said.
The age of 12 billion years for the galaxy relied on the characteristics of two different sets of stars, globular clusters and white dwarfs. But this estimate depends on assumptions about stellar evolution and nuclear physics that scientists have yet to substantiate to their complete satisfaction.
Globular clusters are clusters of stars that exist on the outskirts of a galaxy. The processes of stellar evolution suggested that most of the stars in globular clusters are nearly as old as the galaxy itself. When the big bang occurred 13.7 billion years ago, the only elements in the universe were hydrogen, helium and a small quantity of lithium. The Milky Way?s globular clusters have to be nearly that old because they contain mostly hydrogen and helium. Younger stars contain heavier elements that were recycled from the remains of older stars, which initially forged these heavier elements in their cores via nuclear fusion.
White dwarf stars, meanwhile, are stars that have used up their fuel and have advanced to the last stage of their lives. ?The white dwarf has no source of energy, so it just cools down. If you look at its temperature and you know how fast it cools, then you can approximate the age of the galaxy, because some of these white dwarfs are about as old as the galaxy,? Dauphas said.
A more direct way to calculate the age of stars and the Milky Way depends on the accuracy of the uranium/thorium clock. Scientists can telescopically detect the optical ?fingerprints? of the chemical elements. Using this capability, they have measured the uranium/thorium ratio in a single old star that resides in the halo of the Milky Way.
Original Source: University of Chicago News Release
Rosetta’s photograph of Comet Tempel 1, it’s down on the lower left. Image credit: ESA. Click to enlarge.
ESA?s Rosetta comet-chaser spacecraft has acquired its first view of the Deep Impact target, Comet 9P/Tempel 1.
This first Rosetta image of the Deep Impact campaign was taken by its Navigation Camera (NAVCAM) between 08:45 and 09:15 CEST on 28 June 2005.
The image shows that the spacecraft now points towards Comet 9P/Tempel 1 in the correct orientation. The NAVCAM is pointing purposely slightly off-target to give the best view to the science instrumentation.
The NAVCAM system on board Rosetta was activated for the first time on 25 July 2004. This system, comprising two separate independent camera units (for back-up), will help to navigate the spacecraft near the nucleus of Comet 67P/Churyumov-Gerasimenko in ten years time.
In the meantime though, the cameras can also be used to track other objects, such as Comet Tempel 1, and the two asteroids that Rosetta will be visiting during its long cruise, Steins and Lutetia.
The cameras perform both as star sensors and imaging cameras (but not with the same high resolution as some of its other instruments), and switch functions by means of a refocusing system in front of the first lens.
The magnitude of Comet Tempel 1 is at the detection limit of the camera: it is not as easily visible in the raw image and the image here is a composite of 20 exposures of 30 seconds each.
The comet is the fuzzy object with the tail in the lower left of the image. The faintest stars visible in this image are about 13th magnitude, the bright star in the upper left is about 8th magnitude. The image covers about 0.5 degrees square, and celestial north is to the right.
Original Source: ESA News Release
Story Musgrave on the launch pad for the space shuttle Discovery on mission STS-33. Image credit: NASA. Click to enlarge.
Listen to the interview: Interview with Story Musgrave (10 MB)
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Fraser Cain: We’re just about two weeks away from the next space shuttle going up to return to flight after the Columbia tragedy. How would you feel if you were in the space shuttle?
Story Musgrave: I was never comfortable with the shuttle, of course. The risk is a lot higher than I ever wished to tolerate. I’m not a risk taker. I’ve survived in the aerospace world for 53 years, and I’m a professional who wants to come back and do it again next year. I’ve never been happy with the amount of risk that the shuttle is. But, I think the current mission will probably be one of the safest ever. I think they will have done as much as they can, and they will have looked after the details, so I think this current launch will be as safe as any they’ve ever done.
Fraser: What’s the experience like of launching on board the shuttle? Pretty violent, I guess.
Musgrave: Uh yeah, I’d call it violent. It’s a lot of vibration, a lot of noise, and you’re just hoping that butterfly will just stick to that bullet.
Fraser: There’s been a lot of controversy about the Hubble Space Telescope, about whether to continue the repairs or not. You led the team for the first repair mission. How do you feel about bringing Hubble back to service?
Musgrave: I think we’ll give it one more shot. I think we will go and service it one more time. That’s not over, that game is not over yet, and I expect we’ll service it one more time. It may not be on the books now; what is on the books is don’t preclude it, not to preclude that possibility. I think once we get the shuttle flying again, and certainly the public wants that done. There’s nothing much more important to the public. The public doesn’t understand the space station, they don’t know what’s there, they don’t know what we’re doing, they don’t see anything from it. Once we get the shuttle flying again, and we’ve got an idea about the difficulties there with ice or foam and the thermal protection system, then we’ll get that confidence back. I think we’ll get the confidence to take the shuttle to somewhere other than space station. As you probably know, the only issue is – it’s not a matter of money or anything – the issue is that every time you fly the shuttle until it’s flown out its lifetime, which people are talking 2010; should you take it to the space station every time? You do have a lifeboat, you do have a means of inspection, possibly of repair, and a place for the crew to hang out until rescue if there is a problem. It gets down to the basic question: are you willing to take the risk to fly the shuttle anywhere other than the space station, such as Hubble? You can not make it to Hubble, and then make it to space station. They’re in different planes, and it takes to much fuel to change planes. So you can’t do both. If you go to Hubble, you can’t make it to station.
Fraser: How do you feel about the new Vision for Space Exploration?
Musgrave: A vision of “out there”, I am very happy with, to go beyond Earth orbit. Space station was a terrible strategic error. We’ve not had a solid vision, of course, since the Moon and Skylab. For Skylab, our first space station, I was involved in developing, and as a backup crew member on the first one in 1973. Now the Apollo and the Skylab programs had a vision. We knew where we were going and what we wanted to do, and it was exploration and discovery. It kind of lost the way from that point on, in terms of staying in touch with the public, who wants exploration and discovery, wants a little further out there. The Voyagers, of course, were fantastic successes and this year they’re planning to pull the plug on them just for money purposes when, in fact, the Voyagers are defining the edge of the Solar System. A new vision at least has words “back to the Moon and to Mars”, so it’s a little further out. How that unfolds, of course, no one knows. Where the resources will come from when we transition from the current efforts we’re doing. Until we get out of the current efforts, there’ll be no money for the further out explorations. But they also have to be done right; we can’t leap off and go. We have to lead with the robots. They have to go first to establish habitats and science centres. They need to go first. So then you can do space optimally, low cost option for space. Lead with the robots. We have to do that this time.
Fraser: And do you feel that the US, and maybe the world in general are more interested in space and space exploration then maybe the governments give them credit?
Musgrave: Oh yeah, the people are. The people are usually interested in exploration and discovery; they’re very interested in what kind of Universe they’ve got; what’s their place in it. They’re interested in the big questions. So, that’s what they’re after. That’s what’s exciting about space. Not the spinoffs, not the technical spinoffs, not just the technology. They’re interested in discovering their Universe. They want some answers to their existential questions. What’s life mean here? What’s the meaning of hope? What am I doing here? So things like Hubble tend to bridge those gaps between cosmology and theology, philosophy and astronomy. And that’s why Hubble has always meant so much to people. That’s why for that kind of exploration and discovery, you can do it in a microscope as well. You could do it with really cutting edge science, all those things are exciting to people. But space, going out to beyond Earth, whether you do it with telescopes or other robots or eventually humans, that’s why people are excited about space.
Fraser: Astronomy and the search for life on Mars and so on has a chance to really put things in perspective here in the Universe.
Musgrave: You’ll never know. You can’t know what happened here until you find one other. Of course, contact, you know with linear time and linear distances is going to be very difficult, but no way will we understand how creation, evolution and intelligent beings and the information age all came to pass on this planet. We’ll never understand that until we see how that happened on some other body. And so that is critical, very critical. We’re dealing, as scientists, we’re dealing with a sample of one; how it happened and why it happened. With a sample of one, usually you can’t make conclusions from one. So all those things are highly important. But we can take small steps before we make contact. You can make steps in that the human species accepts the other long before you get the proof of contact. That’s part of our growth, part of our Copernican growth; do we accept other living creatures, and accept other intelligent creatures. It’s all part of the Copernican thing – the Universe does not go around the Earth. It’s part of the Darwinian thing about evolution, it’s part of Freud, of the subconscious, which is very important to human behaviour even though you can’t get at it. It’s Einstein’s Relativity, the Heisenberg uncertainty. Those kinds of things, they are part of our species’ growth. And so I think that long before we get to physical proof of it, that part of our growth will be universal among the species acceptance of the other.
Fraser: Do you think that humans are emotionally ready to make contact with other alien species?
Musgrave: No, they’re not. They’re not, and it won’t happen. Anything that is so advanced as to be doing interstellar travel, and you know with the trillions of planets out there that could support life, there is interstellar travel going on. They wouldn’t come here, we’re not ready. We’re not ready because we are not ready to meet members of our own species. I mean, there are 60 wars this week on planet Earth. So, if we’re not ready to meet – to embrace – members of our own species, let alone other creatures or a sustainable behaviour with Earth, we are not advanced enough in our globalization and in our moving further out until we think of ourselves as galactic creatures on the journey together. No, we’re not ready to meet them, and we would not welcome them – we’d send the guns first. It would be a national defense. It would be a national security issue, as opposed to a communications issue. I’m not a cynic, and I’m not being skeptical, I’m pointing at the facts… the pure facts. But it also points out that humans have got to get it together. They’ve simply got to get the will, the desire, to get it together. And that has not become more important than protecting the tribalism and protecting our provincial interests. You know, globalization of the species, where we become global creatures, and then solar system, and then galactic kinds of creatures which would live at a different transcendent level. That’s obtainable to us today if we only have the desire.
Fraser: Do you think that the universities and the schools and even the popular culture are doing a good job of popularizing space and astronomy and science right now?
Musgrave: Yes, I think they do a good job. That’s not the problem: what do we give them? What are we handing them? For example, let me come back to you and ask you a question, what are we giving them today?
Fraser: On the news, people are interested in Michael Jackson’s trial more than the things being discovered in space.
Musgrave: I absolutely agree that the Michael Jacksons to Britney Spears and the Donald Trumps are running the world. There’s no question about that, and I’m serious, they really are. If you look at the internet, if you look at the explosion of information with 100 television channels, and the massive number of books, magazines, print and the satellite communications, the internet, all the rest of that; if you look upon that as we’re almost forming a global brain here, or we have already – it may even be conscious. That’s a stretch, but how are we to know? You know, a single brain cell doesn’t know it’s part of a brain; it can’t see that great big picture. But the gate guarders, the people who run the media and the like. There are people who, when they sneeze, the entire system reverberates; they kick off huge waves that go through this massive global brain that we have. And it’s not the scientists, and it’s not the scientific information. That’s not necessarily just a problem with the space program, that’s a cultural problem. You want to build the people; you want to make the people so that when they sneeze, the whole brain shivers. You make them, and then you mine money from them. But that’s a process where we really do need to get our priorities and get beyond that.
Fraser: I see a few glimmers of hope, with shows like CSI where the scientists and geeks are the heroes. Back in the 60s and 70s, the astronauts were seen as heroes and as rock stars in that world, so it’s definitely possible. It’s almost as if, this is what’s currently in focus, so that’s all people care about.
Musgrave: I guess it boils down to a sense of values. What are our values? What are our species, what are our cultural, what are our national, what are our values in terms of what do we value?
Fraser: I wanted to go a bit into the recent CD that we reviewed here on Universe Today a little way back. Can you give me some background on what went into doing this CD, and the people that you worked with?
Musgrave: Well, it was mostly my son who was instrumental in that. And we have some other musicians which I adore: Jonn Serrie writes a lot about space music. Harry Roberts, we discovered him. He was just living across the street from Todd in Austin. Brian Eno, I’ve always adored his stuff, the Apollo track, and that. It’s basically a montage of things we recorded some of my poems in the studio, and then Harry added some music to them. It kind of evolved in that way to be a space themed audio.
Fraser: And having finished Cosmic Fireflies, do you think you’ll do another CD?
Musgrave: Yes, I think we will. I think it may focus a little more heavily. The poetry I wrote were mostly class assignments. One poem, the longer poem about orbit about the Earth I wrote for National Geographic magazine. But if I’d had it in mind ahead of time, that we’d put the poems to music, then I would maybe do some different things. But I didn’t know that’s where those things would end up, when I wrote them, or when I recorded them. So it’s possible that with the specificity in mind, it’s possible that I could do a better job although, there’s nothing much like spontaneity. I think a live audience is very nice too, so you might do a live poetry reading. And I do live programs to record on DVDs. I’m just wrapping up one now on Australia from space. I’m going down to Sydney in two weeks and probably put the wraps on that. We’ve been in post production here for a year.
Fraser: One question I get a lot from readers, is how do they become astronauts. One suggestion I’ve heard is to save up $20 million and pay for a trip to space. Do you have any advice for the next generation of astronauts out there?
Musgrave: I disagree with money, I disagree, I think that’s the wrong thing to do. Money, just like we were talking about earlier, who runs the world, with celebrity running the world with celebrity money and power, they all go together of course. I disagree with the idea that money should go into space. The artists, the poets and scientists and other teachers and stuff, they don’t get to go because they don’t have money. So I disagree with that grab for resources. We had a wonderful communicator in space program, teacher in space program, but of course, Christa McAuliffe died on Challenger and we haven’t had the courage to reinstitute that program. We took her backup, Barbara Morgan, we took her on as a regular astronaut so that we would eventually get a teacher into space. The wider range of people you put in space, the more richly you’re going to communicate what space is about. I’ve always been highly in favour of flying a diversity of people in space. Money should not be the deciding factor. Your ability to have the experience and bring it home for others should be the deciding factor. Now, new things are happening; there’s SpaceShipOne, and the Ansari X-Prize. So new things are happening, but it’s not going to open a huge door right away. Space is so critical, you have to do it right. You can’t just do it, you know. You can’t just do it to pull it off. So you have to do more deeper engineering, and backup systems, and safety systems, and escape systems, and you have to get more into those kinds of things. Tourism in space by private enterprise will be a little slower to happen than maybe we perceive now, as we see private ventures getting into it. It’s very important to have those innovative kinds of things happening. It’s exceedingly important because NASA’s not doing it.
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Thanks for all your support, I’d better hurry and do some more interviews.
Fraser Cain
Publisher, Universe Today
The white dwarf star Gliese 86B is the tiny dot to the left of the bright star. Image credit: ESO. Click to enlarge.
The team has found that a star known as Gliese 86 – part of the southern constellation Erinadus, and just visible to the unaided eye – has another companion in addition to the gas giant planet that was found in a tight orbit around it seven years ago. However, this more distant companion is not another planet, but a white dwarf star that is about as far from Gliese 86 as is Uranus from the sun. The discovery marks the first time a planet has been found in the vicinity of a white dwarf, and could have implications for our own solar system – which will itself be centered around a white dwarf in a few billion years.
“This is the first observational evidence that planets can survive the white dwarf formation process of a star several astronomical units away,” said researcher team member Markus Mugrauer, a doctoral student at the Astrophysical Institute and University Observatory, University of Jena, Germany. “In theory, nearby planets should not survive the formation process, but this finding is evidence that, if they are sufficiently distant, they can. This is of interest because most stars in the galaxy, including our own, will eventually evolve into white dwarfs.”
The study, which Mugrauer conducted with Dr. Ralph Neuhaeuser, director of observations at the university’s astrophysics institute, were published as a letter in the May issue of “Monthly Notices of the Royal Astronomical Society.”
The planet itself was discovered in late 1998 at Switzerland’s La Silla observatory, and was the first exoplanet to be found using a telescope at La Silla that had been fitted with a spectrograph for the express purpose of searching for planets around other stars. Further analysis of Gliese 86’s movements indicated that the star also had a faint stellar companion that had not yet been observed, possibly a brown dwarf — an object with insufficient mass to sustain fusion in its core.
“No one was sure what it was, however,” Mugrauer said. “Just as the planet itself had been found by its influence on Gliese 86 but had not actually been ‘seen,’ the companion was tugging on the star but it was difficult to separate from background light.”
To resolve Gliese 86’s companion, the pair used high contrast observations using the 8m Very Large Telescope at La Silla together with a new simultaneous differential imaging device.
“With these instruments, we can resolve objects about 150,000 times fainter than the central star, but which are still very close to them,” Mugrauer said. “This allows us to search for close and very faint companions of our target stars.”
After filtering out the background noise, they found Gliese’s companion orbiting at a distance of about 21 AU, but were surprised to find it hotter than expected — at least 3700 Kelvin, too warm to be a brown dwarf. Judging by its velocity and distance from Gliese 86, they also found that the white dwarf has about 55 percent the mass of our sun, making it smaller than Gliese 86, which has 70 percent of our sun’s mass.
“But since a star loses a good deal of its mass as it evolves into a white dwarf, this companion was once much larger than Gliese 86, perhaps as large as our own sun or even larger,” Mugrauer said. “It was much closer to Gliese 86 before it became a white dwarf, perhaps 15 AU, or a distance about halfway between the orbits of Saturn and Uranus in our own system. It migrated outward after it lost mass during its evolution into a white dwarf.”
Because of the planet’s size and distance from the red giant, Mugrauer said, the companion’s evolution wouldn’t have dramatically affected the planet’s size.
“The planet’s gravity is simply too strong to lose mass because of the impacting material and due to its large separation,” he said. “However, during the red giant phase, the companion would have swollen up and become 10,000 more luminous. It would also have become the dominant heat source of the planet, heating it 1000K or more.”
Nowadays, he said, the companion would probably appear as a very bright star in the planet’s night sky, but would provide it with very little additional heat in comparison with Gliese 86, which the giant planet circles at about a tenth the distance of the Earth to the sun.
“We expect that distant planets — those farther than Jupiter is from our sun — can survive the evolution of a star from red giant to white dwarf. These observations tend to confirm that expectation,” Mugrauer said. “In the Gliese 86 system in particular, the separation between the white dwarf and the exoplanet is large enough that it seems very possible that a planet can survive the red giant phase of a G dwarf such as our sun.”
But Mugrauer said that he and Neuhaeuser would continue to search for companion stars in this and other exoplanetary systems because, despite the number of planets that have been found circling other stars, little is known about the properties of planets in binary systems. Planets in close binaries, like Gliese 86, are rare. “Gliese 86 is one of the closest binary systems hosting a planet,” Mugrauer said.
“These systems provide important information about the planet formation process and how the multiplicity of the host star may effect it,” he said. “Gliese 86 is only about 35 light years from earth, so it was near the top of our list of stars to explore. But we are on our way to checking out a lot more.”
Written by Chad Boutin
