Saturday, 24 September 2011

NASA: Pieces of falling satellite may be down

From John Zarella, CNN
September 24, 2011 -- Updated 0600 GMT (1400 HKT)
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U.S. in falling satellite's strike zone
STORY HIGHLIGHTS
  • NASA is waiting for confirmation that satellite pieces are down
  • About 26 pieces, some weighing hundreds of pounds, are expected to survive reentry
  • It is not clear exactly where the pieces might have landed
Miami (CNN) -- Pieces of a defunct satellite plummeting toward Earth may have come to rest, NASA said Saturday morning
NASA says "it's possible" that the Upper Atmosphere Research Satellite "is down by now," according to the agency's Twitter page early Saturday. But the agency said it is seeking official confirmation with the United States Strategic Command.
About two dozen pieces of the satellite were expected to survive the crash through the Earth's atmosphere.
Late Friday night, NASA predicted satellite parts would pass "over Canada and Africa, as well as vast areas of the Pacific, Atlantic and Indian oceans."
U.S. in falling satellite's strike zone
FAA: Pilots watch for falling satellite
"The risk to public safety is very remote," the space agency added.
It was not immediately clear where fallen pieces may have ended up.
About 26 pieces were expected to survive the descent. Those pieces, made of stainless steel, titanium and beryllium that won't burn, will range from about 10 pounds to hundreds of pounds, according to NASA.
Earlier, NASA said "there is a low probability" surviving debris will land in the United States, but on Saturday morning the space agency tweeted, "The U.S. is very safe from (the satellite) ... It's final orbit did not cross the United States."
Mark Matney of NASA's Orbital Debris team in Houston said there's no way to know exactly where the pieces will come down.
"Keep in mind, they won't be traveling at those high orbital velocities. As they hit the air, they tend to slow down. ... They're still traveling fast, a few tens to hundreds of miles per hour, but no longer those tremendous orbital velocities," he explained.
"Part of the problem is, the spacecraft is tumbling in unpredictable ways, and it is very difficult to very precisely pinpoint where it's coming down even right before the re-entry," Matney said.
Because water covers 70% of the Earth's surface, NASA has said that most -- if not all -- of the surviving debris will land in water. Even if pieces strike dry land, there's very little risk any of it will hit people.
However, in an abundance of caution, the Federal Aviation Administration released an advisory Thursday warning pilots about the falling satellite, calling it a potential hazard.
"It is critical that all pilots/flight crew members report any observed falling space debris to the appropriate (air traffic control) facility and include position, altitude, time and direction of debris observed," the FAA statement said.
The FAA said warnings of this sort typically are sent out to pilots concerning specific hazards they may encounter during flights such as air shows, rocket launches, kites and inoperable radio navigational aids.
NASA said space debris the size of the satellite's components re-enters the atmosphere about once a year. Harvard University astrophysicist Jonathan McDowell noted that the satellite is far from being the biggest space junk to come back.
"This is nothing like the old Skylab scare of the '70s, when you had a 70-ton space station crashing out of the sky. So, I agree with the folks in Houston. It's nothing to be worried about," McDowell said.
Pieces of Skylab came down in western Australia in 1979.
The only wild card McDowell sees is if somehow a chunk hits a populated area.
"If the thing happens to come down in a city, that would be bad. The chances of it causing extensive damage or injuring someone are much higher."

Speed-of-light results under scrutiny at Cern


Opera detectorEnormous underground detectors are needed to catch neutrinos, that are so elusive as to be dubbed "ghost particles"

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A meeting at Cern, the world's largest physics lab, has addressed results that suggest subatomic particles have gone faster than the speed of light.
The team presented its work so other scientists can determine if the approach contains any mistakes.
If it does not, one of the pillars of modern science will come tumbling down.
Antonio Ereditato added "words of caution" to his Cern presentation because of the "potentially great impact on physics" of the result.
The speed of light is widely held to be the Universe's ultimate speed limit, and much of modern physics - as laid out in part by Albert Einstein in his theory of special relativity - depends on the idea that nothing can exceed it.

Start Quote

We want to be helped by the community in understanding our crazy result - because it is crazy”
Antonio EreditatoOpera collaboration
Thousands of experiments have been undertaken to measure it ever more precisely, and no result has ever spotted a particle breaking the limit.
"We tried to find all possible explanations for this," the report's author Antonio Ereditato of the Opera collaboration told BBC News on Thursday evening.
"We wanted to find a mistake - trivial mistakes, more complicated mistakes, or nasty effects - and we didn't.
"When you don't find anything, then you say 'well, now I'm forced to go out and ask the community to scrutinise this'."
Friday's meeting was designed to begin this process, with hopes that other scientists will find inconsistencies in the measurements and, hopefully, repeat the experiment elsewhere.
"Despite the large [statistical] significance of this measurement that you have seen and the stability of the analysis, since it has a potentially great impact on physics, this motivates the continuation of our studies in order to find still-unknown systematic effects," Dr Ereditato told the meeting.
"We look forward to independent measurement from other experiments."
Graphic of the Opera experiment
Neutrinos come in a number of types, and have recently been seen to switch spontaneously from one type to another.
The Cern team prepares a beam of just one type, muon neutrinos, and sends them through the Earth to an underground laboratory at Gran Sasso in Italy to see how many show up as a different type, tau neutrinos.
In the course of doing the experiments, the researchers noticed that the particles showed up 60 billionths of a second earlier than they would have done if they had travelled at the speed of light.
This is a tiny fractional change - just 20 parts in a million - but one that occurs consistently.
The team measured the travel times of neutrino bunches some 16,000 times, and have reached a level of statistical significance that in scientific circles would count as a formal discovery.
But the group understands that what are known as "systematic errors" could easily make an erroneous result look like a breaking of the ultimate speed limit.
That has motivated them to publish their measurements.
"My dream would be that another, independent experiment finds the same thing - then I would be relieved," Dr Ereditato told BBC News.
But for now, he explained, "we are not claiming things, we want just to be helped by the community in understanding our crazy result - because it is crazy".


Faster than light particles found, claim scientists

Particle physicists detect neutrinos travelling faster than light, a feat forbidden by Einstein's theory of special relativity
Subatomic Neutrino Tracks
Neutrinos, like the ones above, have been detected travelling faster than light, say particle physicists. Photograph: Dan Mccoy /Corbis
It is a concept that forms a cornerstone of our understanding of the universe and the concept of time – nothing can travel faster than the speed of light.
But now it seems that researchers working in one of the world's largestphysics laboratories, under a mountain in central Italy, have recorded particles travelling at a speed that is supposedly forbidden by Einstein's theory of special relativity.
Scientists at the Gran Sasso facility will unveil evidence on Friday that raises the troubling possibility of a way to send information back in time, blurring the line between past and present and wreaking havoc with the fundamental principle of cause and effect.
They will announce the result at a special seminar at Cern – the European particle physics laboratory – timed to coincide with the publication of a research paper (pdf) describing the experiment.
Researchers on the Opera (Oscillation Project with Emulsion-tRacking Apparatus) experiment recorded the arrival times of ghostly subatomic particles called neutrinos sent from Cern on a 730km journey through the Earth to the Gran Sasso lab.
The trip would take a beam of light 2.4 milliseconds to complete, but after running the experiment for three years and timing the arrival of 15,000 neutrinos, the scientists discovered that the particles arrived at Gran Sasso sixty billionths of a second earlier, with an error margin of plus or minus 10 billionths of a second.
The measurement amounts to the neutrinos travelling faster than the speed of light by a fraction of 20 parts per million. Since the speed of light is 299,792,458 metres per second, the neutrinos were evidently travelling at 299,798,454 metres per second.
The result is so unlikely that even the research team is being cautious with its interpretation. Physicists said they would be sceptical of the finding until other laboratories confirmed the result.
Antonio Ereditato, coordinator of the Opera collaboration, told the Guardian: "We are very much astonished by this result, but a result is never a discovery until other people confirm it.
"When you get such a result you want to make sure you made no mistakes, that there are no nasty things going on you didn't think of. We spent months and months doing checks and we have not been able to find any errors.
"If there is a problem, it must be a tough, nasty effect, because trivial things we are clever enough to rule out."
The Opera group said it hoped the physics community would scrutinise the result and help uncover any flaws in the measurement, or verify it with their own experiments.
Subir Sarkar, head of particle theory at Oxford University, said: "If this is proved to be true it would be a massive, massive event. It is something nobody was expecting.
"The constancy of the speed of light essentially underpins our understanding of space and time and causality, which is the fact that cause comes before effect."
The key point underlying causality is that the laws of physics as we know them dictate that information cannot be communicated faster than the speed of light in a vacuum, added Sarkar.
"Cause cannot come after effect and that is absolutely fundamental to our construction of the physical universe. If we do not have causality, we are buggered."
The Opera experiment detects neutrinos as they strike 150,000 "bricks" of photographic emulsion films interleaved with lead plates. The detector weighs a total of 1300 tonnes.
Despite the marginal increase on the speed of light observed by Ereditato's team, the result is intriguing because its statistical significance, the measure by which particle physics discoveries stand and fall, is so strong.
Physicists can claim a discovery if the chances of their result being a fluke of statistics are greater than five standard deviations, or less than one in a few million. The Gran Sasso team's result is six standard deviations.
Ereditato said the team would not claim a discovery because the result was so radical. "Whenever you touch something so fundamental, you have to be much more prudent," he said.
Alan Kostelecky, an expert in the possibility of faster-than-light processes at Indiana University, said that while physicists would await confirmation of the result, it was none the less exciting.
"It's such a dramatic result it would be difficult to accept without others replicating it, but there will be enormous interest in this," he told the Guardian.
One theory Kostelecky and his colleagues put forward in 1985 predicted that neutrinos could travel faster than the speed of light by interacting with an unknown field that lurks in the vacuum.
"With this kind of background, it is not necessarily the case that the limiting speed in nature is the speed of light," he said. "It might actually be the speed of neutrinos and light goes more slowly."
Neutrinos are mysterious particles. They have a minuscule mass, no electric charge, and pass through almost any material as though it was not there.
Kostelecky said that if the result was verified – a big if – it might pave the way to a grand theory that marries gravity with quantum mechanics, a puzzle that has defied physicists for nearly a century.
"If this is confirmed, this is the first evidence for a crack in the structure of physics as we know it that could provide a clue to constructing such a unified theory," Kostelecky said.
Heinrich Paes, a physicist at Dortmund University, has developed another theory that could explain the result. The neutrinos may be taking a shortcut through space-time, by travelling from Cern to Gran Sasso through extra dimensions. "That can make it look like a particle has gone faster than the speed of light when it hasn't," he said.
But Susan Cartwright, senior lecturer in particle astrophysics at Sheffield University, said: "Neutrino experimental results are not historically all that reliable, so the words 'don't hold your breath' do spring to mind when you hear very counter-intuitive results like this."
Teams at two experiments known as T2K in Japan and MINOS near Chicago in the US will now attempt to replicate the finding. The MINOS experiment saw hints of neutrinos moving at faster than the speed of light in 2007 but has yet to confirm them.
• This article was amended on 23 September 2011 to clarify the relevance of the speed of light to causality.


OPERA experiment reports anomaly in flight time of neutrinos from CERN to Gran Sasso

Geneva, 23 September 2011. The OPERA1 experiment, which observes a neutrino beam from CERN2 730 km away at Italy’s INFN Gran Sasso Laboratory, will present new results in a seminar at CERN this afternoon at 16:00 CEST. The seminar will be webcast at http://webcast.cern.ch. Journalists wishing to ask questions may do so via twitter using the hash tag #nuquestions, or via the usual CERN press office channels.
The OPERA result is based on the observation of over 15000 neutrino events measured at Gran Sasso, and appears to indicate that the neutrinos travel at a velocity 20 parts per million above the speed of light, nature’s cosmic speed limit. Given the potential far-reaching consequences of such a result, independent measurements are needed before the effect can either be refuted or firmly established. This is why the OPERA collaboration has decided to open the result to broader scrutiny. The collaboration’s result is available on the preprint server arxiv.org: http://arxiv.org/abs/1109.4897.

The OPERA measurement is at odds with well-established laws of nature, though science frequently progresses by overthrowing the established paradigms. For this reason, many searches have been made for deviations from Einstein’s theory of relativity, so far not finding any such evidence. The strong constraints arising from these observations makes an interpretation of the OPERA measurement in terms of modification of Einstein’s theory unlikely, and give further strong reason to seek new independent measurements.

“This result comes as a complete surprise,” said OPERA spokesperson, Antonio Ereditato of the University of Bern. “After many months of studies and cross checks we have not found any instrumental effect that could explain the result of the measurement. While OPERA researchers will continue their studies, we are also looking forward to independent measurements to fully assess the nature of this observation.” 
 “When an experiment finds an apparently unbelievable result and can find no artefact of the measurement to account for it, it’s normal procedure to invite broader scrutiny, and this is exactly what the OPERA collaboration is doing, it’s good scientific practice,” said CERN Research Director Sergio Bertolucci. “If this measurement is confirmed, it might change our view of physics, but we need to be sure that there are no other, more mundane, explanations. That will require independent measurements.”

In order to perform this study, the OPERA Collaboration teamed up with experts in metrology from CERN and other institutions to perform a series of high precision measurements of the distance between the source and the detector, and of the neutrinos’ time of flight. The distance between the origin of the neutrino beam and OPERA was measured with an uncertainty of 20 cm over the 730 km travel path. The neutrinos’ time of flight was determined with an accuracy of less than 10 nanoseconds by using sophisticated instruments including advanced GPS systems and atomic clocks. The time response of all elements of the CNGS beam line and of the OPERA detector has also been measured with great precision.

"We have established synchronization between CERN and Gran Sasso that gives us nanosecond accuracy, and we’ve measured the distance between the two sites to 20 centimetres,” said Dario Autiero, the CNRS researcher who will give this afternoon’s seminar. “Although our measurements have low systematic uncertainty and high statistical accuracy, and we place great confidence in our results, we’re looking forward to comparing them with those from other experiments."

“The potential impact on science is too large to draw immediate conclusions or attempt physics interpretations. My first reaction is that the neutrino is still surprising us with its mysteries. said Ereditato. “Today’s seminar is intended to invite scrutiny from the broader particle physics community.”
The OPERA experiment was inaugurated in 2006, with the main goal of studying the rare transformation (oscillation) of muon neutrinos into tau neutrinos. One first such event was observed in 2010, proving the unique ability of the experiment in the detection of the elusive signal of tau neutrinos.

Further information:


Contact:

CERN Press Office, press.office@cern.ch
+41 22 767 34 32
+41 22 767 21 41

 

Follow CERN at:


1. OPERA has been designed and is being conducted by a team of researchers from Belgium, Croatia, France, Germany, Israel, Italy, Japan, Korea, Russia, Switzerland and Turkey. The experiment constitutes a complex scientific enterprise that has been realised thanks to the skill of a large number of scientists, engineers, technicians and students, and with the strong commitment of the various actors of the project. In particular we mention the LNGS/INFN and CERN laboratories, and the major financial support of Italy and Japan with substantial contributions from Belgium, France, Germany and Switzerland. The OPERA Collaboration presently includes about 160 researchers from 30 institutions and 11 countries:

IIHE-ULB Brussels, Belgium; IRB Zagreb, Croatia; LAPP Annecy, France; IPNL Lyon, France; IPHC Strasbourg, France; Hamburg, Germany; Technion Haifa, Israel; Bari, Italy; Bologna, Italy; LNF, Italy, L’Aquila, Italy; LNGS, Italy; Naples, Italy; Padova, Italy; Rome, Italy; Salerno, Italy; Aichi, Japan; Toho, Japan; Kobe, Japan; Nagoya, Japan; Utsunomiya, Japan; GNU Jinju, Korea; INR RAS Moscow, Russia; LPI RAS Moscow, Russia; ITEP Moscow, Russia; SINP MSU Moscow, Russia; JINR Dubna, Russia; Bern, Switzerland; ETH Zurich, Switzerland; METU Ankara, Turkey.
2. CERN, the European Organization for Nuclear Research, is the world's leading laboratory for particle physics. It has its headquarters in Geneva. At present, its Member States are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, the Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. Romania is a candidate for accession. India, Israel, Japan, the Russian Federation, the United States of America, Turkey, the European Commission and UNESCO have Observer status.

Falling satellite slows down, Earth strike delayed

CAPE CANAVERAL, Fla. (AP) — A 6-ton NASA satellite on a collision course with Earth clung to space Friday, apparently flipping position in its ever-lower orbit and stalling its death plunge.
The old research spacecraft was targeted to crash through the atmosphere sometime Friday night or early Saturday, putting the U.S. back in the potential crosshairs, although most of the satellite should burn up during re-entry.
"It just doesn't want to come down," said Jonathan McDowell of the Harvard-Smithsonian Center for Astrophysics.
McDowell said the satellite's delayed demise demonstrates how unreliable predictions can be. That said, "the best guess is that it will still splash in the ocean, just because there's more ocean out there."
Until Friday, increased solar activity was causing the atmosphere to expand and the 35-foot, bus-size satellite to free fall more quickly. But late Friday morning, NASA said the sun was no longer the major factor in the rate of descent and that the satellite's position, shape or both had changed by the time it slipped down to a 100-mile orbit.
"In the last 24 hours, something has happened to the spacecraft," said NASA orbital debris scientist Mark Matney.
NASA cautioned there was now a slim chance any surviving debris would land in the United States. Earlier this week, the space agency said North America would be in the clear.
"It is still too early to predict the time and location of re-entry with any certainty," NASA said in a statement.
The Aerospace Corp., which tracks space debris, estimates the strike will happen sometime between about 9 p.m. and 3 a.m. EDT, which would make a huge difference in where the debris falls. Those late-night, early morning passes show the satellite flying over parts of the United States.
Any surviving wreckage is expected to be limited to a 500-mile swath.
The Upper Atmosphere Research Satellite, or UARS, will be the biggest NASA spacecraft to crash back to Earth, uncontrolled, since the post-Apollo 75-ton Skylab space station and the more than 10-ton Pegasus 2 satellite, both in 1979.
Russia's 135-ton Mir space station slammed through the atmosphere in 2001, but it was a controlled dive into the Pacific.
Some 26 pieces of the UARS satellite — representing 1,200 pounds of heavy metal — are expected to rain down somewhere. The biggest surviving chunk should be no more than 300 pounds.

Earthlings can take comfort in the fact that no one has ever been hurt by falling space junk — to anyone's knowledge — and there has been no serious property damage. NASA put the chances that somebody somewhere on Earth would get hurt at 1-in-3,200. But any one person's odds of being struck were estimated at 1-in-22 trillion, given there are 7 billion people on the planet.
"Keep in mind that we have bits of debris re-entering the atmosphere every single day," Matney said in brief remarks broadcast on NASA TV.
In any case, finders definitely aren't keepers.
Any surviving wreckage belongs to NASA, and it is against the law to keep or sell even the smallest piece. There are no toxic chemicals on board, but sharp edges could be dangerous, so the space agency is warning the public to keep hands off and call police.
The $740 million UARS was launched in 1991 from space shuttle Discovery to study the atmosphere and the ozone layer. At the time, the rules weren't as firm for safe satellite disposal; now a spacecraft must be built to burn up upon re-entry or have a motor to propel it into a much higher, long-term orbit.
NASA shut UARS down in 2005 after lowering its orbit to hurry its end. A potential satellite-retrieval mission was ruled out following the 2003 shuttle Columbia disaster, and NASA did not want the satellite hanging around orbit posing a debris hazard.
Space junk is a growing problem in low-Earth orbit. More than 20,000 pieces of debris, at least 4 inches in diameter, are being tracked on a daily basis. These objects pose a serious threat to the International Space Station.
___
Online:
Satellite updates: www.nasa.gov/uars
Aerospace Corp: http://reentrynews.aero.org/1991063b.html

NASA's Upper Atmosphere Research Satellite, or UARS, is expected to re-enter Earth's atmosphere late Sept. 23 or early Sept. 24 Eastern Daylight Time, almost six years after the end of a productive scientific life. Although the spacecraft will break into pieces during re-entry, not all of it will burn up in the atmosphere.

The risk to public safety or property is extremely small, and safety is NASA's top priority. Since the beginning of the Space Age in the late-1950s, there have been no confirmed reports of an injury resulting from re-entering space objects. Nor is there a record of significant property damage resulting from a satellite re-entry.

It is still too early to say exactly when UARS will re-enter and what geographic area may be affected, but NASA is watching the satellite closely and will keep you informed. Visit this page for updates on the satellite's orbital track and predicted re-entry date.

› Re-Entry and Risk Assessment (498 KB PDF)
› Frequently Asked Questions: Orbital Debris

The updates posted here come from the Joint Space Operations Center of U.S. Strategic Command at Vandenberg Air Force Base, Calif., which works around the clock detecting, identifying and tracking all man-made objects in Earth orbit, including space junk.

The actual time of re-entry is difficult to predict because it depends on solar flux and the spacecraft's orientation as its orbit decays. As re-entry draws closer, predictions on the date will become more reliable.

Because the satellite's orbit is inclined 57 degrees to the equator, any surviving components of UARS will land within a zone between 57 degrees north latitude and 57 degrees south latitude. It is impossible to pinpoint just where in that zone the debris will land, but NASA estimates the debris footprint will be about 500 miles long.

If you find something you think may be a piece of UARS, do not touch it. Contact a local law enforcement official for assistance.