Bolide in Italy. Credit: Ferruccio Zanotti of Ferrara, Italy, via Spaceweather.com
A fireball seen over Texas during the daytime on Sunday, Feb. 15th, triggered widespread reports that debris from the recent satellite collision was falling to Earth. The FAA even issued a statement that airplanes should watch for falling debris. However, those reports and statements were premature. Researchers have studied video of the event and concluded that the object was more likely a natural meteoroid about one meter wide traveling more than 20 km/s–much faster than orbital debris. Meteoroids hit Earth every day, and the Texas fireball was apparently one of them. Additionally, a spokeswoman for U.S. Strategic Command said the fireball spotted in the Texas skies Sunday was unrelated to the satellite collision. And as always, the Bad Astronomer was on top of it from the beginning, so check out his first post here (which includes several updates as the news broke), and a follow-up here. There were other fireballs, too….
There was one bolide event in central Kentucky on Friday, February 13. People heard loud booms, felt their houses shake, and saw a fireball streaking through the sky. This occurred just hours after another fireball at least 10 times brighter than a full Moon lit up the sky over Italy. Although it is tempting to attribute these events to debris from the Feb. 10th collision of the Iridium 33 and Kosmos 2251 satellites, the Kentucky and Italy fireballs also seem to be meteoroids, not manmade objects. Italian scientists are studying the ground track of their fireball, which was recorded by multiple cameras, and they will soon begin to hunt for meteorites.
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Air Force Major Regina Winchester said that Joint Space Operations Center at California’s Vandenberg Air Force Base has been monitoring the debris from the collision, and that could not have caused the dramatic sight. She also said the fireball was not related to the estimated 18,000 man-made objects that the center also monitors.
“There was no predicted re-entry,” Winchester said about the objects in Earth’s orbit.
She said it was likely a natural phenomenon such as a meteorite.
Ice core from Mars? Not quite. But this aggregation of soil grains, from Antarctica ice, derived from the same process now proposed for the Red Planet (Credit: Hans Paerl, University of North Carolina at Chapel Hill).
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Ice core from Mars? Not quite. But this aggregation of soil grains, from Antarctica ice, derived from the same process now proposed for the Red Planet (Credit: Hans Paerl, University of North Carolina at Chapel Hill)
The puzzling Meridiani Planum deposits on Mars — discovered by NASA’s Opportunity rover — could be remnants of a massive ancient ice field, according to a new study online in Nature Geoscience.
Paul Niles of NASA’s Johnson Space Center and Joseph Michalski, of Université Paris-Sud, analysed the chemistry, sedimentology and geology of the Meridiani Planum deposits using data from Opportunity. They suggest that sulphate formation and chemical weathering occurred within an ice deposit as massive as today’s polar ice caps on Mars. Once the ice sublimed away in a warmer climate, the remaining sediments kept their chemical signature, the authors suggest.
The new theory gets around a weakness in the previous belief, that the deposits were formed in a wet, shallow basin — because no evidence of such a basin has been found yet. But it comes with its own baggage: there’s not much evidence of massive ice in the region, either.
The Meridiani represent one of the flattest areas on the Martian surface, with long, rolling smooth plains, linear dunes and ridges. Based on the number of craters, scientists have speculated that it formed early in the Hesperian Era, roughly 3.8 billion years ago.
The intriguing place — right at the crosshairs of zero degrees longitude and zero degrees latitude — was initially spotted by the Mars Thermal Emission Spectrometer aboard NASA’s Mars Global Surveyor (1996-2006). It was then chosen as the landing site for NASA’s rover Opportunity, in 2004.
“Immediately upon touchdown, when we turned on the cameras for the first time and looked out on the plains, it became obvious that it was a different kind of place on Mars than we’d ever been before,” Michalski said.
Since then, the place has been the object of numerous chemistry studies which have generated a handful of competing theories about how its odd sulfate deposits might have formed. The prevailing theory, fronted by scientists on the Mars Exploration Rovers team, has it that the Meridiani Planum was once a shallow evaporation basin which was periodically wet, where wind helped drive away the moisture and left the deposits behind. Other scientists have proposed a catastrophic event like a volcano or major impact, perhaps with volcanic aerosols altering layered rocks at the surface. Microscopic image of Meridiani Planum sediments. Image of outcrop of sediments at Meridiani Planum inside Endurance crater taken by the microscopic imager on sol 145 (Credit: NASA/JPL/Cornell/USGS).
But Michalski and Niles say the deposits formed when the area was covered with thick ice. Dust trapped within the ice would have warmed in the presence of sunlight, causing minor melting nearby. And because the ice also contained volcanic aerosols, the water that formed would have been highly acidic, and reacted with the dust, yielding the perplexing products in pockets within the ice that became the deposits when the ice sublimed. The same process happens to a limited extent in the Earth’s polar regions, Michalski said. The Meridiani Planum is near the equator, where large ice fields are lacking today. The authors propose that the ice could have formed in ancient times, when the poles were in a different place or when the Martian axis of rotation was at a different angle.
Michalski said the new theory gets around a lot of the sticking points in the older ones.
“It doesn’t require a basin to be present; it doesn’t require the groundwater,” he said. “We like a lot of aspects of the MER team’s hypothesis. One of the big problems is that you have to have a lot of acidic water in that situation.”
Brian Hynek, an atmospheric and space physicist at the University of Colorado in Boulder, had proposed a volcanic origin for the deposits in the past, but he said there are strengths to the new theory as well. For starters, he said, the ice pocket hypothesis could explain why salts of varying water solubility co-exist so closely in the Meridiani Planum deposits.
“The volume of the Meridiani deposits is similar to the amount of sediment contained within the layered ice-rich deposits at Mars’s south pole,” he added. “And sublimation of a sufficiently large dusty ice deposit would provide a convincing source for all the sediment, which other models have failed to provide.”
But he said there are shortfalls to the new theory too: No model has allowed for the necessarily massive ice deposits at the Martian equator, for example, and it’s curious how the dust and aerosols “could aggregate into consistent sand-sized particles” in the examined bedrock.
Hynek said of all the theories that could explain the strange deposits in the Meridiani Planum, none has emerged yet as a clear winner: “All have their strengths and all have significant weaknesses. I don’t think we’ve solved this mystery yet.”
Michalski is less cautious about the implications of the new work.
“We’re able to propose this process for the Meridiani deposits because there are a lot of data,” he said. “We think that it’s likely that the other sulfate deposits on Mars could have been formed by the same mechanism.”
The switch to digital will eliminate the Big Bang channel.
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The switch from analog to digital television broadcasting signals in the United States , which was originally scheduled for February 17th, has been postponed until June 12th, 2009. To those anticipating the higher-quality picture and more reliable signal that this switch will afford, the delay is surely a downer, though some stations may begin broadcasting digital signals before this date. You may be surprised, though, that the change in signal may no longer allow you to see leftover radiation from the Big Bang in the static on your television screen.
That’s right – when you are between channels on an analog television, the snow that you see on the screen is made up of interference from background signals that the antenna on your TV is picking up. Some of the “snow” is from other transmissions here on Earth, and some is from other radio emissions from space. Part of that interference – about 1% or less – comes from background radiation leftover from the Big Bang, called the Cosmic Microwave Background (CMB). The same is true for FM radios – when the radio is tuned to a frequency that is between stations, part of the hiss that you hear, called “white noise”, is leftover radiation from the Big Bang some 13.7 billion years ago.
In other words, your TV and radio are telescopes, good for receiving transmissions here on Earth, but really, really bad telescopes for viewing the Universe (a 1:100 signal-to-noise ratio is pretty poor). Why does your TV or radio allow you to tune into the Big Bang, however poorly? Analog television signals are basically radio waves that your television picks up, decodes, and turns into an image on your television using what’s called a cathode ray tube (CRT) in older televisions, and in newer TVs, plasma displays.
These analog signals are broadcast between 7-1002 Mhz, and TV tuners are designed to receive in this range. The CMB peaks in the microwave, at around 160 Ghz, but the frequency of CMB photons can be lower than 100 Mhz (.1 Ghz). Your television antenna is constantly being bombarded by these signals, but when it’s tuned to a specific station the overwhelming intensity of the signal at that frequency makes a crisp picture on your screen, and drowns out everything else. When your TV or radio isn’t tuned into a channel that is brodcasting clearly, it picks up whatever radio transmissions are available and displays those transmissions as the black and white static that is oh-so annoying when you are trying to acrobatically align your TV antenna and stand in just the right place to clearly show your favorite program. Here’s a short clip from First Science explaining the CMB and white noise.
Digital signals eliminate the interference while watching a program because instead of broadcasting the picture as a radio wave which communicates to the CRT or plasma screen what to “paint” on the screen by the frequency of the signal, all a digital signal communicates is a 1 or 0, and the digital converter takes care of decoding and sending information as to what the picture and sound on your screen should look like.
In fact, it was annoying “noise” that led to the discovery of the Cosmic Microwave Background in the first place. In 1965, Arno Penzias and Robert Wilson had built a Dicke radiometer for Bell Telephone Laboratories to use in radio astronomy and satellite communication experiments. Their instrument kept receiving a background signal that they could not account for. After trying everything imaginable to eliminate the noise (including removing the pigeon droppings from the telescope), they finally realized that the signal wasn’t “noise”, but photons from the Big Bang. Penzias and Wilson share the 1978 Nobel Prize in physics for this discovery, and the CMB has since been studied as a way to learn more about the beginnings of the Universe.
Arno Penzias and Robert Wilson in front of the Horn Antenna. Image Credit: AIP Niels Bohr Library
Televisions manufactured after March 1, 2007 for the U.S. are required to have Digital Television (DTV) tuners or be DTV ready. Some broadcasters are already transmitting TV programs in both analog and digital formats, but they will all be required to broadcast only in digital format after June 12, 2009. If you have an older television that doesn’t contain a built-in DTV tuner, you will have to buy a digital converter box. So, if you want to see static created by the CMB, unplugging the converter after June 12th will suffice. If you have a newer TV that only has a digital tuner, you will sadly be unable to experience that small percentage of influence the ancient event of the Big Bang has on something quotidian as the television in your living room.
The South Pole Telescope under the aurora australis (southern lights). Photo by Keith Vanderlinde
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During the next decade, cosmologists will attempt to observe the first moments of the Universe, hoping to prove a popular theory. They’ll be searching for extremely weak gravity waves to measure primordial light, looking for convincing evidence for the Cosmic Inflation Theory, which proposes that a random, microscopic density fluctuation in the fabric of space and time gave birth to the Universe in a hot big bang approximately 13.7 billion years ago. A new instrument called a polarimeter is being attached to the South Pole Telescope (SPT), which operates at submillimeter wavelengths, between microwaves and the infrared on the electromagnetic spectrum. Einstein’s theory of general relativity predicts that Cosmic Inflation should produce the weak gravity waves.
Inflation Theory proposes a period of extremely rapid and exponential expansion of the Universe during its first few moments prior to the more gradual Big Bang expansion, during which time the energy density of the universe was dominated by a cosmological constant-type of vacuum energy that later decayed to produce the matter and radiation that fill the Universe today.
In 1979, physicist Alan Guth proposed the Cosmic Inflation Theory, which also predicts the existence of an infinite number of universes. Unfortunately, cosmologists have no way of testing that particular prediction. The South Pole Telescope takes advantage of the clear, dry skies at the National Science Foundation’s South Pole Station to study the cosmic background radiation, the afterglow of the big bang. The SPT measures eight meters (26.4 feet) in diameter. Photo by Jeff McMahon
“Since these are separate universes, by definition that means we can never have any contact with them. Nothing that happens there has any impact on us,” said Scott Dodelson, a scientist at Fermi National Accelerator Laboratory and a Professor in Astronomy & Astrophysics at the University of Chicago.
But there is a way to probe the validity of cosmic inflation. The phenomenon would have produced two classes of perturbations. The first, fluctuations in the density of subatomic particles happen continuously throughout the universe, and scientists have already observed them.
“Usually they’re just taking place on the atomic scale. We never even notice them,” Dodelson said. But inflation would instantaneously stretch these perturbations into cosmic proportions. “That picture actually works. We can calculate what those perturbations should look like, and it turns out they are exactly right to produce the galaxies we see in the universe.”
The second class of perturbations would be gravity waves—Einsteinian distortions in space and time. Gravity waves also would get promoted to cosmic proportions, perhaps even strong enough for cosmologists to detect them with sensitive telescopes tuned to the proper frequency of electromagnetic radiation.
If the new polarimeter is sensitive enough, scientists should be able to detect the waves.
“If you detect gravity waves, it tells you a whole lot about inflation for our universe,” said John Carlstrom from the University of Chicago, who developed the new instrument. Carlstrom said detecting the waves would rule out various competing ideas for the origin of the universe. “There are fewer than there used to be, but they don’t predict that you have such an extreme, hot big bang, this quantum fluctuation, to start with,” he said. Nor would they produce gravity waves at detectable levels.
A simulation at this link portrays the distortions in space and time at the subatomic scale, the result of quantum fluctuations occurring continuously throughout the universe. Near the end of the simulation, cosmic inflation begins to stretch space-time to the cosmic proportions of the universe.
Cosmologists also use the SPT in their quest to solve the mystery of dark energy. A repulsive force, dark energy pushes the universe apart and overwhelms gravity, the attractive force exerted by all matter.
Dark energy is invisible, but astronomers are able to see its influence on clusters of galaxies that formed within the last few billion years. NASA’s Wilkinson Microwave Anisotropy Probe collected data that produced this chart of sound waves from the universe. Called a power spectrum, the chart plots the cosmic microwave background radiation as ripples of different sizes across the sky. The data are consistent with predictions of cosmic inflation theory. Courtesy of the WMAP Science Team
The SPT detects the cosmic microwave background (CMB) radiation, the afterglow of the big bang. Cosmologists have mined a fortune of data from the CMB, which represent the forceful drums and horns of the cosmic symphony. But now the scientific community has its ears cocked for the tones of a subtler instrument—gravitational waves—that underlay the CMB.
“We have these key components to our picture of the universe, but we really don’t know what physics produces any of them,” said Dodelson of inflation, dark energy and the equally mysterious dark matter. “The goal of the next decade is to identify the physics.”
The world is not going to end in 2012. If anyone reading this has any doubt about that, you need to read each and every one of Ian O’Neill’s articles here on Universe today about every facet of the 2012 mania. And then if you still have any doubts, here’s another voice you might recognize who will tell you the same thing: Dr. Neil deGrasse Tyson of the Hayden Planetarium and NOVA ScienceNow, has a few choice words for the entities out there spreading fear and disinformation (and looking to make a few bucks along the way) about everything that could possibly (not) happen in 2012.
I also recommend listening to the February 2, 2009 edition of The Planetary Society’s Planetary Radio, where David Morrison, Interim Director of the Lunar Science Institute and Planetary Radio host Mat Kaplan have a discussion (near the end of the show) about how the completely false claims of the 2012 fear mongers are needlessly scaring people. Its sobering.
And the V we’re taking a stereo look at on Valentine’s Day is V838 Monocerotis – an unusual “light echo” from a variable star. If you’re curious to know more about what you’re looking at, then prepare to take a 20,000 light year journey across space and step inside…
Like all our our “stereo” image produced for UT by Jukka Metsavainio, two versions are presented here. The one above is parallel vision – where you relax your eyes and when you are a certain distance from the monitor screen the two images will merge into one to produce a 3D version. The second – which appears below – is crossed vision. This is for those who have better success crossing their eyes to form a third, central image where the dimensional effect occurs. Jukka’s visualizations of what Hubble images would look like if we were able to see them in dimension come from studying the object, its known field star distances and the different wavelengths of light. Are you ready to “cross” the boundary? Then let’s rock…
V838 Monocerotis Cross-Vision by Jukka Metsavainio
When you’re ready to come back to your seat, let’s talk just a little bit about what V838 Monocerotis is and what we currently know about it.
The primary source of light that you’re seeing in here comes from a variable star – the 838th variable star discovered in the constellation of Monocerotis – which underwent a very strange reaction early in 2002. At first astronomers believed it to be a pretty normal nova event, but it didn’t take long to realize this was something altogether different than anything they’d ever witnessed.
When it first began to brighten on January 10, 2002, the light curve measurements began. These graphs show the intensity of light as a function of time – and they came back as ordinary… a white dwarf shedding accumulated hydrogen gas from its binary neighbor. By February 6th, it had reached its maximum visual brightness and started to dim again, just as expected – but only weeks later the infrared wavelength began to do some very strange things – it brightened unexpectedly and did it again just a few more weeks later! This was something astronomers had simply never witnessed…
According to Howard Bond; “Some classes of stars, including novae and supernovae, undergo explosive outbursts that eject stellar material into space. In 2002, the previously unknown variable star V838 Monocerotis brightened suddenly by a factor of ~104. Unlike a supernova or nova, it did not explosively eject its outer layers; rather, it simply expanded to become a cool supergiant with a moderate-velocity stellar wind. Superluminal light echoes were discovered as light from the outburst propagated into the surrounding, pre-existing circumstellar dust. At its maximum brightness (it) was temporarily the brightest star in the Milky Way. The presence of the circumstellar dust implies that previous eruptions have occurred, and spectra show it to be a binary system. When combined with the high luminosity and unusual outburst behaviour, these characteristics indicate that V838 Mon represents a hitherto unknown type of stellar outburst, for which we have no completely satisfactory physical explanation.”
At the time, V838 expanded in size to the point where it would have filled our solar system to the size of Jupiter’s orbit and output a million times the luminosity of our own Sun – changes that happened in an abnormal time span of just months. Since science did have pre-eruption photographs, V838 was thought to be an under luminous F-type dwarf – much like Sol – which deepened the mystery even further. Just what could cause it to go against the laws of thermodynamics?
According to R. Tylenda; “The eruption phase, which lasted till mid-April 2002, resulted from a very strong energy burst, which presumably took place in last days of January at the base of the stellar envelope inflated in pre-eruption. The burst produced an energy wave, which was observed as a strong luminosity flash in the beginning of February, followed by a strong mass outflow in form of two shells, which was observed as an expanding photosphere in later epochs. In mid-April, when the outflow became optically transparent and most of its energy radiated away, the object entered the decline phase during which V838 Mon was evolving along the Hayashi track. This we interpret as an evidence that the main energy source during decline was due to gravitational contraction of the object envelope inflated in eruption. Late in 2002 a dust formation started in the expanding shells which gave rise to a strong infrared excess observed in 2003.”
Since then we’ve learned the V838 eruptive star may have just been entering the main sequence at the time, and we also know it has a B-type companion that’s also just come aboard the main sequence train. This type of information doesn’t add up to a nova event which occurs to older, white dwarfs… even though it may be something we don’t yet understand. It’s possible that V838 Monocerotis may be a post-asymptotic giant branch star – about to end – but again, it doesn’t fit the spectral patterns. According to some evidence, V838 Monocerotis may be a very massive supergiant that experience “carbon flash”… making their way towards the Wolf-Rayet star end of the chapter. It’s possible that the event could have been a “mergeburst” – where a main sequence and pre-main sequence star combined forces – or even a planetary captured event which triggered deuterium fusion.
And maybe we’ll never know in our lifetimes…
No matter if we understand precisely what created it or not, we can still enjoy the wonderful “light echo” produced by V838 Monocerotis, imaged by the Hubble Telescope and visualized for dimension by Jukka. He understands how the light reflects from clouds of interstellar matter between the star and point of the observer. He knows which wavelengths arrived into the camera lens first and which arrived last…
And we’re grateful to have the chance to look straight into the “heart” of this unusual phenomena!
Arabia Terra, a possible MSL landing site on Mars. Credit: NASA/JPL/HiRISE team
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In March 2007, the Spirit rover found a patch of bright-colored soil rich in silica. Scientists proposed water must have been involved in creating the region, and not just water, but hot water. Now, data from retrieved from the Mars Reconnaissance Orbiter (MRO) suggest the discovery of another ancient hot springs region in Vernal Crater in Arabia Terra, an area in the northern hemisphere of Mars that is densely cratered and heavily eroded. The research team says the striking similarities between these features on Mars and hot springs found on Earth provide evidence of an ancient Martian hot-spring environment. On Earth these environments teem with microbial life.
If life forms have ever been present on Mars, hot spring deposits would be ideal locations to search for physical or chemical evidence of these organisms and could be target areas for future exploratory missions such as the Mars Science Labortory. Arabia Terra is currently on the list of possible landing sites for MSL.
In their research paper “A Case for Ancient Springs in Arabia Terra, Mars,” Carlton C. Allen and Dorothy Z. Oehler, from the Astromaterials Research and Exploration Science Directorate at the NASA Johnson Space Center, Houston, Texas, propose that new image data from the HiRISE (High Resolution Imaging Science Experiment) camera on MRO show structures in Vernal Crater that appear to be the product of ancient spring activity. The data suggest that the southern part of Vernal Crater has experienced episodes of water flow from underground to the surface and may be a site where Martian life could have developed.
Vernal Crater is a 55-km diameter crater located at 6°N, 355.5°E, in the southwestern part of Arabia Terra. From orbital images, the crater appears to have layered sediments, and potentially, remnants of activity from water. THEMIS image A. Credit: Allen and Oehler
One feature that is bright in both daytime and nighttime in THEMIS infrared images is prominent in the southern part of Vernal crater. In this image, marked A, the feature appears dark, as the THEMIS grayscale was inverted to resemble HiRISE images in the visible range. The feature is 3 km wide and is composed of alternating light-toned and dark-toned subunits, which the researchers interpret as cemented, resistant dunes,and water-laid deposits.
The research team compares this and other structures in the region with hot springs regions on Earth, using Google Earth. The similarities of the features on Mars and Earth, the researchers say, provides a strong case that the Vernal Crater structures are relics of ancient Martian springs. Regional view of aligned outcrops. CTX image P04_002456_1858. Credit: Allen and Oehlers
The team says their results are consistent with the growing body of orbital and rover data that is suggestive of widespread hydrothermal activity and possible spring deposits elsewhere on Mars.
“If clays or chemical precipitates such as evaporates or silica comprise the terraced structures or tonal anomalies, signatures of that life may be preserved in those minerals,” write the research team in their paper. “The fact that several other potential spring deposits occur on-trend with Vernal structures suggests that this may have been a significant province of long-lasting spring activity.”
A simulated view of the debris clouds shortly after the collision on Feb. 10, 2009. Image courtesy of Analytical Graphics, Inc. (www.agi.com)
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The collision this week involving an active U.S. commercial Iridium satellite and an inactive Russian Cosmos 2251 satellite in low Earth orbit has, if nothing else, raised public awareness of the growing problem of space debris. But how and why did this collision happen? If NORAD, the U.S. Air Forces’s Space Surveillance Network, NASA’s Orbital Debris Program Office and other entities are tracking space debris, did anyone know the collision was going to occur? Those who analyze data and track satellites say predicting collisions is difficult because of changes in satellite orbits which occur due to solar radiation and the gravitational effects of the Moon and Earth. Therefore, the orbit analysis is only as good as the data, which may be imprecise. “The main problem here is the data quality for the data representing the satellites locations,” said Bob Hall, Technical Director of Analytical Graphics, Inc. (AGI), the company that released video and images on Thursday recreating the collision event. “Given the uncertainty in the accuracy of the TLE orbital data, I do not believe anyone was predicting or necessarily expecting an event.”
AGI has tools that run automatically every day such as SOCRATES – (Satellite Orbital Conjunction Reports Assessing Threatening Encounters in Space) which is based on the current space catalog supplied by NORAD to look for close approaches.
“This analysis is performed automatically every day and you can easily go in and search it,” Hall told Universe Today. “Because the analysis is performed with the public two-line element (TLE) set satellite catalog, the analysis is only as good as that imprecise data is. So when it shows conjunctions on any given day (and for Tuesday this Iridium event was not even in the ‘top 10’ close approach predictions!) this has to be taken with some uncertainty.”
Hall said the closest approach predicted for last Tuesday’s Iridium-Cosmos event was predicted to be 584 meters. “Again, as close as that sounds (and it is), there were at least 10 other on-orbit conjunction predictions that day alone with smaller miss distances,” Hall said. Simulation of the satellite debris break-up. Image courtesy of Analytical Graphics, Inc. (www.agi.com)
The crash occurred on Tuesday 485 miles above northern Siberia in a crowded polar orbit used by satellites that monitor weather, relay communications and perform scientific surveys.
The International Space Station, as well as most satellites can be maneuvered out of harm’s way to avoid a possible collision, but a defunct satellite like the Russian Cosmos 2251 has no such ability.
Even with the uncertainties of tracking orbiting satellites, one group, the Secure World Foundation, is calling for the need to establish a civil space traffic control system.
“Unfortunately, it appears that there was data warning about the possibility of this collision beforehand,” noted Brian Weeden, Technical Consultant for Secure World Foundation. “However, it must be stressed that close approaches between satellites somewhere in Earth orbit occurs on almost a weekly basis…and until this event, have never before resulted in an actual collision.”
Weeden agreed that in every case it is impossible to give a definite answer on whether or not two objects will actually collide, only probabilities and potential risks.
“Getting the right information to the right authorities in time to make the right avoidance maneuver decision is a very complicated process that doesn’t entirely exist yet,” Weeden said. “The Secure World Foundation is working with many other organizations around the world to try and develop this process.”
The Secure World Foundation endorses the creation of a space traffic control system.
“This collision underscores in a dramatic way the importance of instituting an international civil space situational awareness (SSA) system as soon as possible,” said Dr. Ray Williamson Executive Director of Secure World Foundation.
Williamson said that such a civil SSA system could have been used to warn the Iridium operations managers of the danger of collision and allow them to take evasive action. “In the absence of reliable ways to clear debris from orbit, it will be increasingly important to follow all active satellites to prevent future preventable collisions,” he added.
Before this collision, another collision event happened in 1996, when a French spy satellite called Cerise was severely damaged by a piece of debris from the rocket that launched it.
The United States tracks debris or micro-meteorites down to 10 cm wide, but objects as small as a scrap of peeled-off paint can pose a threat once they start hurtling at orbital speeds through space.
With a target launch date of March 5, NASA’s Kepler mission is just weeks away from its tantalizing journey to peer at faraway stars and the Earth-like planets they may be hosting. Hundreds of astronomers from all over the world have a stake in the data. The United States participants hail from all the usual astronomy hubs, among them Arizona, California, Texas and … Iowa? Steve Kawaler, an astrophysicist at Iowa State University, took a moment to chat with Universe Today about his role in a less-publicized goal of the Kepler mission — and his research out of a less-publicized astronomy program.
Q. Why Iowa?
Kawaler: Iowa’s a great place. I’m originally a New Yorker, and went to grad school at the University of Texas, but landing at Iowa State (mostly by chance) still feels right.
(Still Kawaler:) You can get a lot of work done here. We’ve organized and run the Whole Earth Telescope from here for about 10 years. A few years ago [in 2004], the WET team showed a pulsating white dwarf (BPM 37093, but later dubbed the ‘Diamond Star’) may truly be crystalline. Finding one of the biggest diamonds in the cosmos and announcing it around Valentine’s Day was pretty fun! I’ve been part of some big collaborations where nearly all the work is done remotely, and that is important as we stare at the mountain of data we’re about to see.
Q. What’s your role in the Kepler mission?
Kawaler: I serve on the Steering Committee for the Kepler Asteroseismology Research Consortium. We’ll use the exquisite time-series measurements of the brightness of over 100,000 stars to measure their internal properties. The KASC has over 250 scientists involved, and the Steering Committee is charged with helping organize and coordinate their efforts in reducing and interpreting the data.
Q. What’s most exciting about the science in this mission?
Kawaler: The most exciting discovery will be the discovery of Earth-like planets around other stars. It’s what we all wonder about – are there other planets out there that host life? That said, most of the stars that Kepler examines won’t show any signs of planetary transits … but the data will provide a gold mine of information about how stars behave. From the point of view of my own research, the most exciting thing that will come out will be improvement, by a factor of almost 100, in the measure of brightness of over 100,000 stars. Asteroseismologists are drooling at this prospect, because we expect to find oscillations in many stars, but this huge increase in sensitivity is bound to reveal new phenomena that we can’t even guess at yet.
Q. A press release described part of your interest as “peering into stars.” Can you elaborate?
Kawaler: Until very recently, everything we know about stars, we learned from looking at the outsides. When you want to really need to know what’s going on, you need some sort of probe that goes beneath the surface. For the Earth, seismic waves generated by earthquakes give you that kind of probe. For stars, we have to measure their vibrations from (very!) far away. Those vibrations produce only tiny signals — very subtle brightness variations. We can also look at how the surfaces move up and down and use those as a measure of the oscillations that are going on inside. Once we do make those measurements, we use the tools that terrestrial seismologists have developed, along with some of our own that are adapted to the special circumstances within stars, to probe the insides of the stars.
Q. Why can’t we do this work from Earth?
Kawaler: The short answer is that we can, sort of, but Earth is a really poor place to do this kind of work. An astronomer can only look at a star for a couple hours a night before the star sets or the sun comes up. It’s kind of the equivalent of listening to Beethoven’s 5th Symphony and listening to every third note. You can sort of do it from the ground by putting together a network of telescopes. We’ve had some remarkable successes. But it’s much easier if you can observe from a platform that isn’t rotating. And if that platform is above the atmosphere, you get the added benefit of a direct line of sight to the star that doesn’t have the atmosphere degrading the image. With continuous views and no atmosphere, Kepler can do way, way better than we can from the ground.
6. Is this helping to realize a life-long ambition for you?
Kawaler: Absolutely – I’ve always been a space program ‘geek.’ I grew up in the 60s. My older brother grew up in the 50s, and he got caught up in the whole Sputnik thing. There were all these books and toys about space; I picked them up and was instantly fascinated. Later, I was just riveted to the TV all the time, watching Gemini and the Apollo missions. I guess I still haven’t grown out of it. My brother is one of the few rabbis that dresses as Captain Kirk on Purim, Jewish Halloween, so I guess he didn’t grow out of it, either. I’m actually heading down to Florida for the launch, with my father, so he can finally be convinced I didn’t have to be a ‘real doctor’ — I can be a PhD.
On Tuesday, a communications satellite in the Iridium fleet suffered complete obliteration at the hands of a defunct Russian satellite Cosmos 2251. Although satellites have been hit by space junk in the past (four times since 1996), this is the first time a satellite has suffered a direct hit… from another satellite. The aftermath of the collision was messy and US Space Command is tracking hundreds of pieces of debris. There is some concern the ex-satellite parts could collide with other active satellites or even the International Space Station (although the odds are still well within safety margins for the crew), but much effort is being put into tracking and modelling the new space junk additions.
If you thought AGI was quick at assembling those superb satellite animations only a day after the event, you’ll be even more impressed with the company who lost their expensive piece of kit. Iridium has a replacement satellite. A spare. Already in orbit. And plans are afoot to “plug the hole” in the satellite phone network. Now that’s what I call service!
The Iridium constellation - a robust satellite network (AGI)It’s probably to be expected, especially when considering competition in the communication industry, but it is an amazing feat to have a backup plan enacted only a couple of days after losing an expensive satellite. But this isn’t only a plan, it’s a satellite, already in orbit, waiting to be powered up and redirected to its predecessor’s old orbit (or at least fulfil it’s coverage on the ground).
Although Iridium was concerned about patchy service for some customers, the satellite network’s mesh design will lower the likelihood of any service outages. So put your satellite phone away, the signal should still be strong.
“The Iridium service hole patch addresses a significant portion of outages that customers otherwise might have experienced,” said Iridium spokesperson Liz DeCastro. “Due to the mesh design of the Iridium network, the company expects further impact to customers to be limited.”
So it sounds as if it’s a sturdy network that can easily deal with one lost component, but the best was yet to come in the press release. “The company also is taking the necessary steps to replace the lost satellite with one of its in-orbit spares, and the operational planning stage is underway,” DeCastro added.
Naturally, Iridium is investigating the incident, saying that they are working “with the appropriate government agencies”. At this time it is unclear whether Iridium will be seeking compensation from the Russian government, but this is a possibility. After all, dead satellites should either be de-orbited or moved from the paths of operational satellites. Unfortunately for Iridium 33, Cosmos 2251 was left at an altitude used by commercial satellite companies.
There may be no LEO traffic control, and there is certainly no “right of way” in space, the responsibility to dispose of space junk lies with the satellite’s last owner. In this case, that would be Russia.
