Encounters with Comet Hartley 2

by Greg Bryant and the editors of Sky & Telescope

The diffuse coma of Comet Hartley 2 was more than 1° wide on October 13th, when Nick Howes took this image with a 4-inch apochromatic refractor in Wiltshire, U.K. Stars are shown by short exposures in the blue and green channels; the comet is shown as a full-color long exposure. Howes has also been remotely operating the 2-meter Faulkes North Telescope in Hawaii. Using this he has measured the rotation rate of the comet's nucleus to be 19 ± 1.5 hours.

Nick Howes

 

More Images

Comet Hartley 2 a "6-inch spinning cucumber!"

Twelve radar images of the nucleus of comet Hartley 2 were obtained by the Arecibo Observatory's planetary radar from Oct 25 to 27, 2010. Image credit: NAIC-Arecibo/Harmon-Nolan 

 Provided by JPL/NASA (news : web)

 Exactly one week before the world gets a new look at comet Hartley 2 via NASA's EPOXI mission, observations of the comet by the Arecibo Planetary Radar in Puerto Rico have offered scientists a tantalizing preview. 

"It kind of looks like a cross between a bowling pin and a pickle," said EPOXI project manager Tim Larson of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Only it's about 14-thousand-times larger and hurtling through space at 23 miles per second." A new image is online at http://www.naic.ed … ~pradar/103P . 

Scientists using Arecibo's massive radar dish began observations of Hartley 2 on Oct. 24, just four days after the comet made its closest approach to Earth since its discovery in 1986. (On Oct. 20, the comet came within 17.7 million kilometers, or 11 million miles, of Earth). The observations are scheduled to continue through Friday, Oct. 29. 

During the Nov. 4 flyby, the cameras aboard the EPOXI mission spacecraft will get within 700 kilometers (about 435 miles) of the comet.\

"Observing comet Hartley 2 from the Earth with radar was like imaging a 6-inch spinning cucumber from 836 miles away," said Jon Giorgini, a scientist at JPL and a member of the Arecibo team that imaged the comet. "Even without all the data in, we can still make some basic assertions about Hartley 2. Its nucleus is highly elongated and about 2.2 kilometers [1.4 mile] long, and it rotates around itself about once every 18 hours. In addition we now know the size, speed and direction of particles being blown off the comet, and we immediately forwarded all this information to the EPOXI team." 

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Space station on to the 2nd decade (ISS)

NASA astronaut Tracy Caldwell Dyson, Expedition 24 flight engineer, replaces a dewar tray containing biological samples in the Minus Eighty Degree Laboratory Freezer for ISS in the Kibo laboratory of the International Space Station. Image Credit: NASA

Provided by JPL/NASA (news : web)

The second decade of a new era in human history -- when not everyone lives on our home planet -- begins Nov. 2, 2010, as the International Space Station crosses the 1.5 billion mile mark of its travels with six residents on board and six visitors en route. 

 On Oct. 25, the station also set a record for being the longest continuously inhabited spacecraft. On that day, the International Space Station eclipsed the previous record of 3,644 days set by the Russian Mir Space Station. With each new day, NASA and its partners are pushing the envelope of human achievement in space into uncharted territory.

Ten years ago, Bill Shepherd, Yuri Gidzenko and Sergei Krikalev launched into history as the first crew to live on the International Space Station. They blasted off from the Baikonur Cosmodrome in Kazakhstan on Oct. 31, 2000, and docked with the station two days later. From the moment the hatch of their Soyuz spacecraft opened and they entered the fledgling space station, there have been people living and working in orbit, 24 hours a day, seven days a week, 365 days a year.

“As we look forward to the next 10 years, taking us through 2020, the space station will serve many roles,” said Mike Suffredini, International Space Station program manager since 2005. “With its permanent human presence, it will serve as a foothold for long-term exploration into space, being an integral part of testing human endurance, equipment reliability and processes essential for space exploration.”

Before his launch, Expedition 1 commander Shepherd explained that the station “gives us unique access to the space environment where we hope we can do very interesting and productive research, but it really means we [will] develop a lot of the capabilities and technology that’ll allow humans to go elsewhere away from the planet.”

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Leaks delay final launch of space shuttle Discovery

The launch of the space shuttle Discovery on its final scheduled mission has been delayed by at least 24 hours until Tuesday because of a leak in a pressurization system, NASA said.

"We have developed two leaks on the pressurization system on the maneuvering system of Discovery on the right side," Kennedy Space Center spokesman Allard Beutel told AFP on Friday.

Fixing the shuttle and getting it ready for take-off would take until "Tuesday at the earliest," the spokesman added.

Discovery and its crew of six astronauts had been scheduled to launch Monday on its last mission to the International Space Station, but that now has been reset for 4:17 pm (2017 GMT) Tuesday, assuming repairs are successful, NASA said.

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Eutelsat suffers spacecraft loss

By Jonathan Amos
Science correspondent, BBC News   

The Paris-based Eutelsat company says its latest spacecraft has failed less than 24 hours after being launched on an Ariane rocket from French Guiana.

The satellite operator said the W3B platform had developed a leak in its propellant system and could not raise itself to its operational orbit.

The 5.3-tonne spacecraft was to have been stationed high above the equator at 16 degrees East, to provide TV, radio, internet and other data services to Europe, Africa, the Middle East and Indian Ocean islands.

The company already has another satellite in production called W3C, and this will be moved into the 16-East slot when it launches in the second half of 2011.

"It's a massive disappointment," said Eutelsat's Vanessa O'Connor, "but our job now as an operator is to continue our services and make sure W3C gets there as soon as possible, and that we expedite the new programme to replace W3B," she told BBC News.

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Time Will End in Five Billion Years, Physicists Predict

Ker Than

for National Geographic News

Published October 28, 2010

Our universe has existed for nearly 14 billion years, and as far as most people are concerned, the universe should continue to exist for billions of years more.

But according to a new paper, there's one theory for the origins of the universe that predicts time itself will end in just five billion years—coincidentally, right around the time our sun is slated to die.

The prediction comes from the theory of eternal inflation, which says our universe is part of the multiverse. This vast structure is made up of an infinite number of universes, each of which can spawn an infinite number of daughter universes. (Related: "New Proof Unknown 'Structures' Tug at Our Universe.")

The problem with a multiverse is that anything that can happen will happen an infinite number of times, and that makes calculating probabilities—such as the odds that Earth-size planets are common—seemingly impossible.

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Superhero suit to strengthen astronauts' bones

Source: NewScientist 

 

WITH its stitching clearly visible and reference lines drawn in marker pen, the stretchy superhero-blue suit at the Massachusetts Institute of Technology's Man Vehicle Laboratory doesn't look like much. But if it works as planned it could offer orbiting astronauts a replacement for something they are sorely missing: gravity.

The microgravity of orbital flight is tough on the bones. Even with regular exercise, an astronaut can lose 1.5 per cent of the mass of some bones in the hips and lower back in just one month. That is similar to the bone loss experienced by a post-menopausal woman in a year.

To combat the problem, Russian cosmonauts on the International Space Station wear space suits designed to mimic gravity. Bungee cords on the suit's arms and legs exert a force that simulates the body's weight. But these suits are difficult to wear for long periods, and it is not clear how effective they are in preventing bone loss.

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Mars Rover Spirit Finds Evidence of Water

Above, we see two of Spirit's wheels stuck in the sand on the Martian surface -- the same location where the rover found evidence of water.

Source: Discovery News

Stuck in the sand and with time to spare, Spirit hits the jackpot.

Stuck in the sands of Mars, the grounded Spirit rover unearthed evidence of subsurface water in the planet's recent past.

"It's total serendipity," Washington University planetary scientist Ray Arvidson told Discovery News. "We're driving backwards, the right front wheel doesn't work, so wherever we went we had to drag it along. It's like pushing a shopping cart with a bad front wheel. You don't push it, you pull it, but the wheel has torque."

The rover ended up getting stuck, breaking through the crust and -- surprisingly -- discovering telltale byproducts of water passing through the exceptionally silica-rich patch of soil.

"This sand wasn't normal looking," Arvidson said.

So, with nowhere to go and time to spare, scientists started a layer-by-layer look at what likely will become Spirit's final resting spot.

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HUBBLE DATA USED TO LOOK 10,000 YEARS INTO THE FUTURE

Astronomers are used to looking millions of years into the past. Now scientists have used the NASA/ESA Hubble Space Telescope to look thousands of years into the future. Looking at the heart of Omega Centauri, a globular cluster in the Milky Way, they have calculated how the stars there will move over the next 10,000 years.

The globular star cluster Omega Centauri has caught the attention of sky watchers ever since the ancient astronomer Ptolemy first catalogued it 2,000 years ago. Ptolemy, however, thought Omega Centauri was a single star. He didn't know that the "star" was actually a beehive swarm of nearly 10 million stars, all orbiting a common center of gravity.

The stars are so tightly crammed together that astronomers had to wait for the powerful vision of NASA's Hubble Space Telescope to peer deep into the core of the "beehive" and resolve individual stars. Hubble's vision is so sharp it can even measure the motion of many of these stars, and over a relatively short span of time.

A precise measurement of star motions in giant clusters can yield insights into how stellar groupings formed in the early universe, and whether an "intermediate mass" black hole, one roughly 10,000 times as massive as our Sun, might be lurking among the stars.

Analyzing archived images taken over a four-year period by Hubble's Advanced Camera for Surveys, astronomers have made the most accurate measurements yet of the motions of more than 100,000 cluster inhabitants, the largest survey to date to study the movement of stars in any cluster.

"It takes high-speed, sophisticated computer programs to measure the tiny shifts in the positions of the stars that occur in only four years' time," says astronomer Jay Anderson of the Space Telescope Science Institute in Baltimore, Md., who conducted the study with fellow Institute astronomer Roeland van der Marel. "Ultimately, though, it is Hubble's razor-sharp vision that is the key to our ability to measure stellar motions in this cluster."

Adds van der Marel: "With Hubble, you can wait three or four years and detect the motions of the stars more accurately than if you had waited 50 years on a ground-based telescope."

The astronomers used the Hubble images, which were taken in 2002 and 2006, to make a movie simulation of the frenzied motion of the cluster's stars. The movie shows the stars' projected migration over the next 10,000 years.

Identified as a globular star cluster in 1867, Omega Centauri is one of roughly 150 such clusters in our Milky Way Galaxy. The behemoth stellar grouping is the biggest and brightest globular cluster in the Milky Way, and one of the few that can be seen by the unaided eye. Located in the constellation Centaurus, Omega Centauri is viewable in the southern skies.

Images and more information about Omega Centauri:  
* http://hubblesite.org/news/2010/28
* http://www.nasa.gov/hubble

The Release Was Received Jointly From The Space Telescope
Science Institute In Baltimore, Maryland, And The Hubble European
Space Agency Information Centre In Garching, Germany

NASA’S KEPLER SPACECRAFT TAKES PULSE OF DISTANT STARS

An international cadre of scientists that used data from NASA's Kepler spacecraft announced Tuesday the detection of stellar oscillations, or "starquakes," that yield new insights about the size, age and evolution of stars.

The results were presented at a news conference at Aarhus University in Denmark by scientists representing the Kepler Asteroseismic Science Consortium (KASC). The team studied thousands of stars observed by Kepler, releasing what amounts to a roster of some of humanity's most well-characterized stars.

Analysis of stellar oscillations is similar to how seismologists study earthquakes to probe the Earth's interior. This branch of science, called asteroseismology, produces measurements of stars the Kepler science team is anxious to have.

"Using the unparalleled data provided by Kepler, KASC scientists are quite literally revolutionizing our understanding of stars and their structures," said Douglas Hudgins, Kepler Program Scientist at NASA Headquarters in Washington. "What's more, they are doing so at no cost to the American taxpayer. All the KASC scientists are supported by research funding from their home countries. It is a perfect illustration of the tremendous value that our international partners bring to NASA missions."

In the results presented Tuesday, one oscillating star took center stage: KIC 11026764 has the most accurately known properties of any star in the Kepler field. In fact, few stars in the universe are known to similar accuracy. At an age of 5.94 billion years, it has grown to a little over twice the diameter of the Sun and will continue to do so as it transforms into a red giant. The oscillations reveal that this star is powered by hydrogen fusion in a thin shell around a helium-rich core.

"We are just about to enter a new area in stellar astrophysics," said Thomas Kallinger, lead author on a study of red giant stars and postdoctoral fellow at the Universities of British Columbia and Vienna. "Kepler provides us with data of such good quality that they will change our view of how stars work in detail."

KASC scientists also reported on the star RR Lyrae. It has been studied for more than 100 years as the first member of an important class of stars used to measure cosmological distances. The brightness, or light wave amplitude, of the star oscillates within a well-known period of about 13.5 hours. Yet during that period, other small cyclic changes in amplitude occur -- behavior known as the Blazhko effect.

The effect has puzzled astronomers for decades, but thanks to Kepler data, scientists may have a clue as to its origin. Kepler observations revealed an additional oscillation period that had never been previously detected. The oscillation occurs with a time scale twice as long as the 13.5-hour period. The Kepler data indicates the doubling is linked to the Blazhko effect.

"Kepler data ultimately will give us a better understanding of the future of our Sun and the evolution of our galaxy as a whole," said Daniel Huber, lead author on one of the KASC studies.

Launched in March 2009, Kepler was designed to discover Earth-size planets orbiting other stars. The spacecraft uses a huge digital camera, known as a photometer, to continuously monitor the brightness of more than 150,000 stars in its field of view as it orbits around the Sun. Kepler searches for distant worlds by looking for "transits," when a planet passes in front of a star, briefly causing it to dim. The amount of dimming reveals the size of the planet compared to the size of the star.

More information about the findings by the KASC scientists: http://astro.phys.au.dk/KASC/

More information about the Kepler mission: http://www.nasa.gov/kepler
http://www.nasa.gov/kepler