Pioneer Anomaly

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Named after the Pioneer 10 and 11 space probes, the Pioneer anomaly refers to the fact that they seem to be moving a teensy bit different from how we think they should be moving (or, more technically, the spacecraft seem to be subject to an unmodeled acceleration whose direction is towards the Sun).

The anomaly was first noticed, by John Anderson, in 1980, when analysis of tracking data from the spacecraft showed a small, unexplained acceleration towards the Sun (this was first published in 1995, with the main paper appearing in 1998). Since then it has been studied continuously, by quite a few scientists.

The Pioneer anomaly is one of the (very few!) true mysteries in contemporary physics, and is a great example of how science is done.

The first step – which Anderson and colleagues took – was to work out where the spacecraft were, and how fast they were traveling (and in what direction), at as many times as they could. Then they estimated the effects of gravity, from all known solar system objects (from the Sun to tiny asteroids and comets). Then they estimated the effects of things like radiation pressure, and possible outgassing. Then … They also checked whether other spacecraft seemed to have experienced a similar anomalous acceleration (the net: not possible to get an unambiguous answer, because all others have known – but unmodelable – effects much bigger than the Pioneer anomaly). Several independent investigations have been conducted, using different approaches, etc.

In the last few years, much effort has gone into trying to find all the raw tracking data (this has been tough, many tapes have been misplaced, for example), and into extracting clean signals from this (also tough … the data were never intended to be analyzed this way, meta-data is sorely lacking, and so on).

And yet, the anomaly remains …

… there’s an unmodeled acceleration of approximately 9 x 10-10 m/s2, towards the Sun.

The Planetary Society has been funding research into the Pioneer anomaly, and has a great summary here! And you can be a fly on the wall at a meeting of a team of scientists investigating the Pioneer anomaly, by checking out this Pioneer Explorer Collaboration webpage.

Universe Today has several stories on the Pioneer anomaly, for example The Pioneer Anomaly: A Deviation from Einstein Gravity?, Is the Kuiper Belt Slowing the Pioneer Spacecraft?, and Ten Mysteries of the Solar System.

Astronomy Cast has two episodes covering the Pioneer anomaly, The End of Our Tour Through the Solar System, and the November 18th, 2008 Questions Show.

Source:
The Planetary Society

Physicists Tie Beam of Light into Knots

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Imagine taking a beam of light and tying it in knots like a piece of string. Hard to fathom? Well, a group of physicists from the UK have achieved this remarkable feat, and they say understanding how to control light in this way has important implications for laser technology used in wide a range of industries.

“In a light beam, the flow of light through space is similar to water flowing in a river,” said Dr. Mark Dennis from the University of Bristol and lead author of a paper published in Nature Physics this week. “Although it often flows in a straight line – out of a torch, laser pointer, etc – light can also flow in whirls and eddies, forming lines in space called ‘optical vortices.’ Along these lines, or optical vortices, the intensity of the light is zero (black). The light all around us is filled with these dark lines, even though we can’t see them.”

Optical vortices can be created with holograms which direct the flow of light. In this work, the team designed holograms using knot theory – a branch of abstract mathematics inspired by knots that occur in shoelaces and rope. Using these specially designed holograms they were able to create knots in optical vortices.

This new research demonstrates a physical application for a branch of mathematics previously considered completely abstract.

“The sophisticated hologram design required for the experimental demonstration of the knotted light shows advanced optical control, which undoubtedly can be used in future laser devices,” said Miles Padgett from Glasgow University, who led the experiments

“The study of knotted vortices was initiated by Lord Kelvin back in 1867 in his quest for an explanation of atoms,” addeds Dennis, who began to study knotted optical vortices with Professor Sir Michael Berry at Bristol University in 2000. “This work opens a new chapter in that history.”

Paper: Isolated optical vortex knots by Mark R. Dennis, Robert P. King, Barry Jack, Kevin O’Holleran and Miles J. Padgett. Nature Physics, published online 17 January 2010.

Source: University of Bristol

How Do You Pronounce ‘Uranus’?


Uranus is the planet with the funny name and the odd orientation. So, when you say the word ‘Uranus’ do you stress the first syllable or the second? Or, perhaps you do as Dr. Pamela Gay suggests, in order to avoid “being made fun of by any small schoolchildren … when in doubt, don’t emphasize anything and just say ‘Uranus.’ And then run, quickly.”

This video is the latest offering from “Sixty Symbols,” a video series put together by the University of Nottingham which provides explanations for the “squiggly lines and Greek letters that astronomers and physicists use to describe physical properties of the Universe and how they apply to modern life,” said Dr. Amanda Bauer, who gave a presentation about Sixty Symbols at the dotAstronomy conference I attended in December (and who is the first person you see on the Uranus video.)

Sixty Symbols covers symbols like Lambda and the Hubble Constant (H) to the speed of light (c), imaginary numbers (j) and propulsion efficiency — explaining their meanings in everyday language, and taking advantage of the passion and the unique senses of humor the scientists at The University of Nottingham all seem to possess!

Bauer said, however, the real genius behind these videos is filmmaker Brady Haran.

In the fall of 2009, the Sixty Symbols team completed their first sixty symbols, and they proved so popular they are now working on another sixty. The project follows The University of Nottingham’s ‘Periodic Table of Videos’ project , which features an entertaining short film about the properties of every single element in the Periodic Table, from aluminium to xenon.

Check out the Sixty Symbols website, and the Sixty Symbols You Tube site to learn more

You can also watch Bauer’s dotAstronomy presentation about Sixty Symbols here.

The Invasion of “Teapots From Space!”

With a combination of alien invasion and British invasion, a new video series provides an amusing way to learn about different aspects of astronomy and space. “Teapots from Space” was created by UK astronomers Edward Gomez, Jon Yardley and Olivia Gomez, and these vodcasts convey lots of science in a short and entertaining package.

“The aim of the series to make astronomy a bit more light hearted but still give a good representation of the science,” said Edward Gomez, from Cardiff University. “I took a lot of inspiration from Douglas Adams when I wrote the episodes, and so the Teapots are like a cross between a sci-fi B-movie and Douglas Adams’ ‘Hitchhikers Guide to the Galaxy.'”

The Teapots come to learn about Earth and the humans that inhabit it. They abduct human scientists who explain all the questions the Teapots have about astronomy, technology and space. But before sending them back to Earth, the scientists’ minds are wiped so they don’t remember the abduction. Sometimes, disembodied robot astronomers provide the answers. Don’t worry, though: no astronomers were harmed in the making of these “potcasts.”

“There are lots of vodcasts available in the world of science but I wanted to make some which were fun and accessible but did not turn down the volume on the science,” Gomez said. “The idea of the Teapots from Space came into being as a vehicle for telling different scientific stories. Nothing is taken too seriously, but the science is all correct.”

Currently there are four episodes available, and another should be released soon. The first episode is about space junk while #2 is about the Herschel and Planck spacecraft; episode 3 is about how to spot (and abduct) astronomers, and the newest episode is about supernovae.

So, settle in on a comfy chair for some afternoon tea and tasty biscuits to watch Teapots From Space.

Butterflynauts Emerge from Cocoons on ISS

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Four “butterflynauts” have emerged on the International Space Station. They are part of a suitcase sized educational experiment that was rocketed to space on Nov. 16 on space shuttle Atlantis as part of the STS-129 mission. Students of all ages and the public are invited to follow the tiny crew’s development from larvae to adult butterflies in the microgravity of space.

In over 100 classrooms across the U.S., students have set up habitats and are replicating the space experiment. Their objective is to compare the growth and behavior of ground-based butterfly larvae and adult butterflies with those living in the microgravity environment of space. New pictures and videos and Powerpoint slides are available almost daily.

A free Butterflies in Space teacher’s guide can be downloaded from BioEd Online at the Butterflies in Space website here. The project is sponsored by National Space Biomedical Research Institute.

Initial results show that there appears to be no difference in the development rates of these butterflies in a microgravity environment as compared to Earth’s gravity, which is a fairly significant finding. While microgravity environment has obvious impacts on human health and physiology, relatively little is known about how microgravity whould effect human growth and development. While there are major differences between humans and butterflies, basic cellular divisions in follow similar processes. Therefore, the success of the butterfly experiment in space indicates that a human embryo could potentially survive and develop normally in space even in the absence of gravity.

Explore the Universe with [email protected]

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If you’re looking for some superb space and astronomy vodcasts, ESA has produced a series of informative video podcasts that explore our Universe as seen through the “eyes” of ESA’s fleet of science spacecraft. “The [email protected] podcast series was started as part of an education and public outreach project for the International Year of Astronomy,” said Dr. Salim Ansari, from ESA’s Directorate of Science and Robotic Exploration, “but it will continue on past IYA, continuing to cover more missions and discoveries.”

The series is a high quality video podcast with HD graphics and stunning visuals. Ansari said the production all done in house.

“One of my favorites is actually the first podcast that shows how with our eyes we see just a small portion of the electromagnetic spectrum,” Ansari said. “But we demonstrate how the different spacecraft can provide insight across the whole spectrum.”
ESA podcast screenshot.
Other podcasts delve into specifics of the electromagnetic spectrum that will be explored by the new Planck (microwave) and Herschel (infrared) spacecraft, to learning about the Gaia galaxy mapper mission that will determine the position of a billion stars.

A new 7th podcast will be released next week that introduces the solar system as seen by the Venus Express, Mars Express, Rosetta, Cassini-Huygens, SoHO and Cluster.

See the [email protected] page for a complete list of podcasts.

Ig Nobel Prizes Awarded for 2009

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Ahh, the wonders of science! But some science is just a little more wonderful than others. For the really great and wonderful science there are the Nobel Prizes. For the off-the-beaten-path and unusual science, Harvard University’s Annals of Improbable Research magazine awards the “Ig Nobel” Prizes, touted as “research that makes people laugh and then think.” Prizes were doled out Oct. 1, but if you are in the Massachusetts area, you might want to attend a free lecture given by the winners on Oct. 3 at 1:00 pm EDT. Here are the 2009 winners:

Veterinary medicine: Catherine Douglas and Peter Rowlinson for showing that cows with names give more milk than unnamed cows.

Peace: Stephan Bolliger, Steffen Ross, Lars Oesterhelweg, Michael Thali and Beat Kneubuehl for investigating whether it is better to be struck over the head with a full beer bottle or with an empty beer bottle.

Economics: Executives of four Icelandic banks for showing how tiny banks can become huge banks, and then become tiny banks again.

Chemistry: Javier Morales, Miguel Apatiga and Victor Castaño for creating diamonds out of tequila.

Medicine: Donald Unger for cracking just the knuckles on his left hand for 60 years to see whether knuckle-cracking contributes to arthritis.

Physics: Katherine Whitcome, Liza Shapiro and Daniel Lieberman for figuring out why pregnant women don’t tip over.

Literature: The Irish national police for issuing 50 tickets to one Prawo Jazdy, which in Polish means “driver’s license.”

Public health: Elena Bodnar, Raphael Lee and Sandra Marijan for inventing a brassiere than can be converted into a pair of gas masks.

Mathematics: Gideon Gono and the Zimbabwean Reserve Bank for printing bank notes in denominations from 1 cent to $100 trillion.

Biology: Fumiaki Taguchi, Song Guofu and Zhang Guanglei for demonstrating that bacteria in panda poop can help reduce kitchen waste by 90%.

Source: Annals of Improbable Research.

UFOs This Weekend? No, Just an Experiment


Reports of UFOs skyrocketed last weekend along the east coast of the US after a NASA launched an experiment to study an unusual phenomenon called noctilucent clouds, or ‘night shining’ clouds. The Charged Aerosol Release Experiment (CARE) was conducted by the Naval Research Laboratory and the Department of Defense Space Test Program, created artificial noctilucent cloud using the exhaust particles of the rocket’s fourth stage at about 173 miles altitude. It created a bright object with a fan-shaped tail, prompting calls of concern from residents in Virginia and Massachusetts to local authorities. But this object was definitely identified.

The experiment used a Black Brant XII Sounding Rocket launched from NASA’s Wallops Flight Facility in Virginia on September 19, 2009 at 7:46 p.m. EDT (2346 GMT).
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Scientists aren’t sure what causes noctilucent clouds. Some think they’re seeded by space dust. Others suspect they’re a telltale sign of global warming.

See our previous post with pictures about noctilucent clouds.

Data collected during the experiment will provide insight into the formation, evolution, and properties of noctilucent clouds, which are typically observed naturally at high latitudes. In addition to the understanding of noctilucent clouds, scientists will use the experiment to validate and develop simulation models that predict the distribution of dust particles from rocket motors in the upper atmosphere.

Natural noctilucent clouds, also known as polar mesospheric clouds, are found in the upper atmosphere as spectacular displays that are most easily seen just after sunset. The clouds are the highest clouds in Earth’s atmosphere, located in the mesosphere around 50 miles altitude.

They are normally too faint to be seen with the naked eye and are visible only when illuminated by sunlight from below the horizon while the Earth’s surface is in darkness.

A team from government agencies and universities, led by the Naval Research Laboratory, is conducting the experiment. In addition to the Naval Research Laboratory, participants include the DoD STP, NASA, University of Michigan, Air Force Research Laboratory, Clemson University, Stanford University, University of Colorado, Penn State University and Massachusetts Institute of Technology/Haystack Observatory.

Source: NASA

After Loss of Lunar Orbiter, India Looks to Mars Mission

India Moon Mission

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After giving up on re-establishing contact with the Chandrayaan-1 lunar orbiter, Indian Space Research Organization (ISRO) Chairman G. Madhavan Nair announced the space agency hopes to launch its first mission to Mars sometime between 2013 and 2015. Nair said the termination of Chandrayaan-1, although sad, is not a setback and India will move ahead with its plans for the Chandrayaan-2 mission to land an unmanned rover on the moon’s surface to prospect for chemicals, and in four to six years launch a robotic mission to Mars.


“We have given a call for proposal to different scientific communities,” Nair told reporters. “Depending on the type of experiments they propose, we will be able to plan the mission. The mission is at conceptual stage and will be taken up after Chandrayaan-2.”

On the decision to quickly pull the plug on Chandrayaan-1, Nair said, “There was no possibility of retrieving it. (But) it was a great success. We could collect a large volume of data, including more than 70,000 images of the moon. In that sense, 95 percent of the objective was completed.”

Contact with Chandrayaan-1 may have been lost because its antenna rotated out of direct contact with Earth, ISRO officials said. Earlier this year, the spacecraft lost both its primary and back-up star sensors, which use the positions of stars to orient the spacecraft.

The loss of Chandrayaan-1 comes less than a week after the spacecraft’s orbit was adjusted to team up with NASA’s Lunar Reconnaissance Orbiter for a Bi-static radar experiment. During the maneuver, Chandrayaan-1 fired its radar beam into Erlanger Crater on the moon’s north pole. Both spacecraft listened for echoes that might indicate the presence of water ice – a precious resource for future lunar explorers. The results of that experiment have not yet been released.

Chandrayaan-1 craft was designed to orbit the moon for two years, but lasted 315 days. It will take about 1,000 days until it crashes to the lunar surface and is being tracked by the U.S. and Russia, ISRO said.

The Chandrayaan I had 11 payloads, including a terrain-mapping camera designed to create a three-dimensional atlas of the moon. It is also carrying mapping instruments for the European Space Agency, radiation-measuring equipment for the Bulgarian Academy of Sciences and two devices for NASA, including the radar instrument to assess mineral composition and look for ice deposits. India launched its first rocket in 1963 and first satellite in 1975. The country’s satellite program is one of the largest communication systems in the world.

Sources: New Scientist, Xinhuanet