Universe Today

February 15, 2011December 24, 2015 by Ken Kremer

Stardust-NExT zooms by Comet Tempel 1 for Cosmic Encounter

Comet Tempel 1 imaged by NASA's Stardust on Feb 14, Valentine’s Day. NASA's Stardust-NExT mission took this image of comet Tempel 1 at 8:38 p.m. PST (11:38 p.m. EST) on Feb 14, 2011. . The comet was first visited by NASA's Deep Impact mission in 2005. Credit: NASA/JPL-Caltech/Cornell **Update Feb 15**: Beautifully sharp Comet images now being downlinked. New story upcoming.

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NASA’s Stardust-NExT comet chaser successfully zoomed by Comet Temple 1 exactly as planned a short while ago at 11:37 p.m. EST on Feb. 14.

The cosmic Valentine’s Day encounter between the icy comet and the aging probe went off without a hitch. Stardust snapped 72 science images as it raced by at over 10 km/sec or 24,000 MPH and they are all centered in the cameras field of view. The probe came within 181 km (112 miles) of the nucleus of the volatile comet.

The images are being transmitted back now and it will take a several hours until the highest resolution images are available for the science team and the public to see. The first few images from a distance of over a thousand miles can be seen here

Tempel 1 is the first comet to be visited twice by spaceships from Earth. The primary goal was to find out how much the comet has changed in the five years since she was last visited by NASA’s Deep Impact mission in 2005, says Joe Ververka of Cornell University, who is the principal investigator of the Stardust-NExT mission. Deep Impact delivered a 375 kg projectile which blasted the comet and created an impact crater and an enormous cloud of dust so that scientists could study the composition and interior of the comet.

“We are going to be seeing the comet just after its closest passage to the sun. We know the comet is changing because the ice melts. We hope to see old and new territory and the crater and complete the Deep Impact experiment.”

Stardust-NExT is a repurposed spacecraft. Initially christened as Stardust, the spaceships original task was to fly by Comet Wild 2 in 2004. It also collected priceless cometary dust particles from the coma which were safely parachuted back to Earth inside a return canister in 2006. High powered science analysis of the precious comet dust will help researchers discern the origin and evolution of our solar system.

Stardust-NExt approaching Comet Tempel 1.
Artist concept of NASA's Stardust-NExT mission, which will fly by Comet Tempel 1 on Feb. 14, 2011. Credit: NASA/JPL-Caltech/LMSS

Stardust was hurriedly snapping high resolution pictures every 6 seconds and collecting data on the dust environment during the period of closest approach which lasted just about 8 minutes. The anticipation was building after 12 years of hard work and a journey of some 6 Billion kilometers (3.5 Billion miles)

“The Stardust spacecraft did a fantastic job,” says Tim Larson, the Stardust-NExT mission project manager from the Jet Propulsion Laboratory (JPL), Pasadena, Calif. “Stardust has already flown past a asteroid and a comet and returned comet particles to Earth”

“Because of the flyby geometry the antenna was pointed away from earth during the encounter. Therefore all the science images and data was stored in computer memory on board until the spacecraft was rotated to point towards Earth about an hour after the flyby.”

Each image takes about 15 minutes to be transmitted back to Earth by the High Gain Antenna at a data rate of 15,800 bits per second and across about 300 million miles of space.

NASA had bracketed five special images from the closest range as the first ones to be sent back. Instead, the more distant images were sent first. It will take about 10 hours to receive all the images.

So everyone had to wait a few hours longer to see the fruit of their long labor. Most of the team from NASA, JPL and Lockheed Martin has been working on the mission for a dozen years since its inception.

“We had a great spacecraft and a great team,” says Ververka. “Apparently, everything worked perfectly. The hardest thing now is we have to wait a couple of hours before we see all the goodies stored on board.”

The entire flyby was carried out autonomously using a preprogrammed sequence of commands. Due to the vast distance from Earth there was no possibility for mission controllers to intervene in real time.

Confirmation of a successful fly by and science imaging was not received until about 20 minutes after the actual event at about 11:58 p.m. EST. The dust flux monitor also registered increased activity just as occurred during the earlier Stardust flyby of Comet Wild 2 in 2004.

The Stardust-NExT science briefing on NASA TV will be delayed a few hours, until perhaps about 4 p.m. EST

Check back here later at Universe Today, on Tuesday, Feb. 15 for continuing coverage of the Valentine’s Day encounter of Stardust-NExT with the icy, unpredictable and fascinating Comet Tempel 1

Comet Tempel 1 imaged by NASA's Stardust on Feb 14, Valentine’s Day.
NASA's Stardust-NExT mission took this image of comet Tempel 1 at 8:36 p.m. PST (11:36 p.m. EST) on Feb 14, 2011, from a distance of approximately 2200 km (1360 miles). The comet was first visited by NASA's Deep Impact mission in 2005. Credit: NASA/JPL-Caltech/Cornell

Stardust-NExT Spacecraft & Comet Tempel 1.
Artist rendering of upcoming flyby on February, 14, 2011. Credit: NASA

Stardust-NExT: 2 Comet Flybys with 1 Spacecraft.
Stardust-NExT made history on Valentine’s Day - February, 14, 2011 – Tempel 1 is the first comet to be visited twice by spacrecraft from Earth. Stardust has now successfully visited 2 comets and gathered science data: Comet Wild 2 in 2004 (left) and Comet Tempel 1 in 2011 (right). Artist renderings Credit: NASA. Collage: Ken Kremer.

February 14, 2011December 24, 2015 by Ken Kremer

From Mars with Love on Valentines Day

A heart-shaped feature in the Arabia Terra region of Mars is show on the left, with additional context on the right, in excerpts of an image taken by the Context Camera on NASA's Mars Reconnaissance Orbiter. Image Credit: NASA/JPL-Caltech/MSSS

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Happy Valentine’s Day from Mars to all the readers of Universe Today !

Well it’s truly a solar system wide Valentines celebration. From the Moon, Mars and even Comet Temple 1 with some pixie Stardust for the romantic rendezvous upcoming in a few short hours [Stardust-NExT Flyby at 11:37 p.m. EST Feb 14].

The Martian camera team from Malin Space Systems, San Diego, wishes to share a special heart-shaped feature from Arabia Terra – images above and below – with all Mars fans on this St. Valentine’s Day, Feb. 14, 2011. And certainly, I love Mars ! Especially those gorgeous and brainy twin gals Spirit & Opportunity.

Heart-shaped feature in Arabia Terra on Mars at 21.9 degrees north latitude, 12.7 degrees west longitude. Credit: NASA/JPL-Caltech/MSSS.

The image was taken on May 23, 2010 – at the start of northern summer on Mars – by the Malin-built and operated Context Camera on NASA’s Mars Reconnaissance Orbiter.

The bright heart shaped feature is about 1 kilometer (0.6 mile) long. Arabia Terra lies in the northern hemisphere of Mars

The tip of the heart lies above a small impact crater centered at 21.9 degrees north latitude, 12.7 degrees west longitude.

According to a JPL press release, “The crater is responsible for the formation of the bright, heart-shaped feature. When the impact occurred, darker material on the surface was blown away, and brighter material beneath it was revealed.

PIA13799: Heart-Shaped Feature in Arabia Terra (Wide View). Credit: NASA/JPL-Caltech/MSSS.

Some of this brighter material appears to have flowed further downslope to form the heart shape, as the small impact occurred on the blanket of material ejected from a much larger impact crater.

The Jet Propulsion Laboratory, Pasadena, Calif manages MRO for NASA.

More Martian hearts images below from another Malin built camera aboard NASA’s Mars Global Surveyor orbiter

Happy Valentines Day from Mars Global Surveyor (MGS)
This heart shaped pit on Mars is located on the east flank of the Alba Patera volcano in northern Tharsis. The pit was formed by collapse within a straight-walled trough known in geological terms as a graben. Graben are formed along fault lines by expansion of the bedrock terrain. Credit: NASA/JPL-Caltech/MSSS.

10 Martian Hearts for Valentine’s Day.
Mesas and depressions from all across Mars. Images taken by Mars Global Surveyor from 2001 to 2004. Credit: NASA/JPL-Caltech/MSSS.

Heart shaped landforms on Mars – or perhaps a box of chocolates !
Image taken by Mars Global Surveyor. Credit: NASA/JPL-Caltech/MSSS

February 14, 2011December 24, 2015 by Nancy Atkinson

More Help on the Way for Verifying ExoPlanets in Kepler’s Dataset

The HARPS-N spectrograph will be installed on the 3.6-meter Telescopio Nazionale Galileo in the Canary Islands. Credit: INAF

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With the Kepler spacecraft finding over 1,200 planetary candidates, the next step is verifying their actual status. That will be a big job, but help is on the way. In April 2012, a new spectrograph called HARPS-North will come online to help confirm and characterize Kepler’s planetary candidates. It will be mounted on the 3.6-meter Telescopio Nazionale Galileo (TNG) in the Canary Islands.

“The Kepler mission gives us the size of a planet, based on the amount of light it blocks when it passes in front of its star. Now we need to measure planetary masses, so that we can calculate the densities. That will allow us to distinguish rocky planets and water worlds from ones dominated by atmospheres of hydrogen and helium,” explained astronomer David Latham from the Harvard-Smithsonian Center for Astrophysics (CfA).

If the name HARPS (High-Accuracy Radial velocity Planet Searcher) is familiar, it is because this new instrument is a duplicate the successful design of an existing instrument in the Southern Hemisphere, the original HARPS spectrograph whichoperates on the 3.6-meter European Southern Observatory telescope at La Silla, Chile. At the TNG telescope, the new HARPS-North will be able to study the same region of the sky viewed by the Kepler spacecraft, within the northern constellations of Cygnus and Lyra.

The Harvard-Smithsonian CfA is part of an international collaboration building the new instrument.

Kepler main field of view. Credit: NASA/JPL - Caltech

Verifying a exoplanet can be tricky. In some circumstances, an eclipsing binary star can mimic the shallow dimming due to a planet crossing in front of its star. Ground-based measurements are needed to verify an orbiting world by spotting the gravitational wobbles it induces in its host star, in a method known as radial velocity.

A spectrograph operates by splitting the light from a star into its component wavelengths or colors, much like a prism. Chemical elements absorb light of specific colors, leaving dark lines in the star’s spectrum. Those lines shift position slightly due to the Doppler shift created by the gravitational tug of an orbiting planet on its star.

The new HARPS-North will be augmented by technology now under development, such as a laser comb for wavelength calibration, which will allow it to detect subtle radial-velocity signals.

“We have set up an enthusiastic collaboration among various institutions to build a northern copy of HARPS. We all expect HARPS-N to be as successful as its southern ‘brother,'” said HARPS-N principal investigator Francesco Pepe of the Astronomical Observatory of Geneva.

“HARPS-N will pursue the most interesting targets found by Kepler, at a level that no one else in the world can do,” said Dimitar Sasselov, Director of the Harvard Origins of Life Initiative. “HARPS-N will partner with Kepler to characterize worlds enough like Earth that they might be able to support life as we know it.”

Source: Harvard Smithsonian CfA

February 14, 2011March 3, 2023 by Nancy Atkinson

Carnival of Space #184

The latest Carnival of Space is a spacey love poem, penned by Darnell Clayton (with a little help from several space bloggers) over at Colony Worlds.

Click here to read the Carnival of Space #184, Carnival of the Space Geeks, a Love Poem.

And if you’re interested in looking back, here’s an archive to all the past Carnivals of Space. If you’ve got a space-related blog, you should really join the Carnival. Find out more by sending an email to [email protected].

February 14, 2011December 24, 2015 by Nancy Atkinson

Sun Unleashes Biggest Flare of the Current Cycle

A M6.6 solar flare peaked at 17:38 UT on Feb. 13, 2011. This is the largest solar flare so fare from this solar cycle based on X-ray irradiance magnitude. Credit: NASA/SDO

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On February 13, 2011, sunspot 1158 let loose the strongest solar flare of the current solar cycle, a blast of radiation across the electromagnetic spectrum, from radio waves to x-rays and gamma-rays. NASA’s Solar Dynamics Observatory recorded an intense flash of extreme ultraviolet radiation, as seen above, and located in approximately the middle of the Sun’s disk in the image below. The eruption also produced a loud blast of radio waves, and coronagraph data from STEREO-A and SOHO agree that the explosion produced a fast but not particularly bright coronal mass ejection. Spaceweather.com predicts a CME cloud will likely hit Earth’s magnetic field on or about Feb. 15th, and high-latitude sky watchers should be alert for auroras.

A M6.6-category flare on Feb. 13. Credit: NASA/SDO

This was an M6.6-category flare. Find out more about the classification of solar flares at this link at Spaceweather.com

Another view from SDO of the flare. Credit: NASA/SDO

A look at sunspot 1158 as of Feb. 14, 2011. This is the source of the recent activity on the Sun. Credit: NASA/SDO

Jason Major from Lights in the Dark created the video below of magnetic activity around a sunspot 1158, from data region from SDO spacecraft, during February 12-13, 2011.

Keep tabs on the Sun by visiting the SDO website, which shows the current Sun in several different wavelengths.

Sources: SDO, Spaceweather.com

February 14, 2011December 24, 2015 by Nancy Atkinson

The Moon Loves You

A heart-shaped crater in the Galilae region on the Moon. Credit: ASA/GSFC/Arizona State University; 3-D by Nathanial Burton-Bradford.

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Happy Valentines Day from everyone here at Universe Today, and the Moon, too. In 3-D, no less.

Thanks to Nathanial Burton-Bradford for sending us this image. He found it while searching through the Lunar Reconnaissance Orbiter Camera’s data set. Check out Nathanial’s Flickr page for larger versions of this one, and more. See the image below in its proper orientation for viewing in 3-D:

February 13, 2011December 24, 2015 by Ken Kremer

Romantic Valentines Day Encounter Looms with Icy Comet

NASA's Romantic Rendezvous in space on Valentine’s Day - Feb. 14. The planned Valentine's Day (Feb. 14, 2011) rendezvous between NASA's Stardust-NExT mission and Comet Tempel 1 inspired this chocolate-themed artist's concept. Credit: NASA/JPL-Caltech. Video and graphics below illustrate the icy encounter and animate the flyby trajectory. NASA TV: Live Coverage listed below. Update: See below the latest navigation camera images taken on Feb. 11 – newly obtained from JPL. These images are crucial for precisely aiming Stardust-NExT

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At last, NASA embraces a romantic rendezvous in the dark void of deep space.

And soon the whole world can watch the up close meet up of the hot Stardust probe and the volatile, icy comet. The historic space tryst is less than a day away!

The Stardust-NExT spacecraft successfully hot fired its thrusters for the final course correction maneuver (TCM-33) on Feb. 12, setting up the fleeting celestial encounter with Comet Tempel 1 on Valentine’s Day, Feb. 14, Monday, at 11:37 p.m. EST. The space science probe will fly by the speeding comet at a distance of approximately 200 kilometers (124 miles) and at a speed of 10 km/sec.

Naturally, the fleeing comet is icy, unpredictable and exploding with jets of gas and dust particles. So there is some uncertainly at NASA and amongst the science team as to what we’ll actually see when the cameras unveil the hidden secrets of the nucleus of Temple 1.

The encounter phase has begun now (Feb. 13) at 24 hours prior to closest approach (Feb. 14) and concludes 24 hours after closest approach.

“The final TCM burn on Feb. 12 went well,” JPL spokesman DC Agle told me today (Feb.13)

It’s been a long wait and a far flung journey. Stardust has cruised some 6 Billion kilometers through our solar system – looping several times around the sun over a dozen years and is now nearly bereft of fuel.

For three and a half long years, the anticipation has been building since NASA approved the repurposing of the Stardust spacecraft in 2007 and fired the thrusters to alter the probes trajectory to Comet Temple 1 for this bonus extended mission.

But until the photos are transmitted across 300 million kilometers of space back to Earth, we won’t know which face of the comets surface was turned towards the camera as the curtain pulls back for the revealing glimpse.

Everything hinges on how accurately the mission team aims the reliable probe and the finicky rotation of the changeable comet.

The irregularly shaped nucleus of Tempel 1 measures barely 5 to 8 km in diameter.

Stardust-NExT: 2 Comet Flybys with 1 Spacecraft.
Stardust-NExT makes history on Valentine’s Day - February, 14, 2011
Tempel 1 is the first comet to be visited twice by spacecraft from Earth. Stardust will have visited 2 comets and gathered science data: Comet Wild 2 in 2004 (left) and Comet Tempel 1 in 2011 (right).
Artist renderings Credit: NASA. Collage: Ken Kremer.

The Feb. 14 encounter marks the first time in history that a comet has been visited twice by spaceships from Earth. The revisit provides the first opportunity for up-close observations of a comet both before and after a single orbital pass around the sun.

In July 2005, NASA’s Deep Impact probe delivered a 375 kg projectile that penetrated at high speed directly into the comets nucleus. The blast created an impact crater and ejected an enormous cloud of debris that was studied by the Deep Impact spacecraft as well as an armada of orbiting and ground based telescopes.

Somewhat unexpectedly, the new crater was totally obscured from the cameras view by light reflecting off the dust cloud.

“The primary goal is to find out how much the comet’s surface has changed between two close passages to the sun since it was last visited in 2005,” says Joe Ververka of Cornell University, who is the principal investigator of the Stardust-NExT mission.

This time around, researchers hope to determine the size of the crater. Numerous bets hinge on that determination.

It’s also quite possible that the crater itself has significantly changed in the intervening five and one half years as the Jupiter-class comet orbits between Mars and Jupiter.

“Comets rarely behave,” says Tim Larson, the Stardust-NExT mission project manager from the Jet Propulsion Laboratory (JPL), Pasadena, Calif.

“Temple 1 exhibits a complex rotation. The rotation period is about 41 hours. But the trajectory changes due to the comet jets and activity.”

“Ideally we would like to obtain photos of old and new territory and the crater from the Deep Impact encounter in 2005,” Larson explained.

“Tempel 1 is the most observed comet in history using telescopes worldwide as well as the Hubble and Spitzer Space Telescopes.”

Engineers are using all this data to fine tune the aim of the craft and get a handle on which sides of the comet will be imaged. But either way the team will be elated with the science results regardless of whether the images reveal previously seen or new terrain.

Today, Feb. 13, mission controllers at JPL are uplinking the final flyby sequences and parameters for Monday’s (Feb. 14) historic encounter.

Stardust-NExT will take 72 high resolution images of Comet Tempel 1 during the close approach. The team expects the nucleus to be resolved in several of the closest images. These will be stored in an onboard computer and relayed back to Earth starting about three hours later.

“All data from the flyby (including the images and science data obtained by the spacecraft’s two onboard dust experiments) are expected to take about 10 hours to reach the ground,” according to a NASA statement.

3 D stereo view of Comet Wild 2 from Stardust flyby in 2004. Credit: NASA/

Stardust-NExT is a repurposed spacecraft and this will be the last hurrah for the aging probe. Stardust was originally launched way back in 1999 and accomplished its original goal of flying through a dust cloud surrounding the nucleus of Comet Wild 2 on Jan. 2, 2004. During the flyby, the probe also collected comet particles which were successfully returned to Earth aboard a sample return capsule which landed in the Utah desert in January 2006.

Stardust continued its solitary voyage through the void of the space. Until now !

Watch the Stardust-NExT Romantic Rendezvous: Live on NASA TV

NASA has scheduled live mission commentary of the flyby and a post encounter news briefing on Feb. 14 and Feb. 15. These will be televised on NASA TV as follows:

February 14, Monday
11:30 p.m. – 1 a.m. (Feb. 15) – Live Stardust-NExT Mission Commentary (including coverage of closest approach to Comet Tempel 1 and re-establishment of contact with the spacecraft following the encounter) – JPL

February 15, Tuesday
3 – 4:30 a.m. Live Stardust-NExT Mission Commentary (resumes with the arrival of the first close-approach images of Comet Tempel 1) – JPL

1 p.m. – Stardust-NExT Post-Encounter News Briefing – JPL

Five facts you should know about NASA’s Stardust-NExT spacecraft as it prepares for a Valentine’s “date” with comet Tempel 1. From a NASA Press Release

1. “The Way You Look Tonight” – The spacecraft is on a course to fly by comet Tempel 1 on Feb. 14 at about 8:37 p.m. PST (11:37 p.m. EST) — Valentine’s Day. Time of closest approach to Tempel 1 is significant because of the comet’s rotation. We won’t know until images are returned which face the comet has shown to the camera.

Stardust- Earth return capsule with cometary dust particles in 2006. Credit: NASA/JPL

2. “It’s All Coming Back To Me Now” – In 2004, Stardust became the first mission to collect particles directly from a comet, Wild 2, as well as samples of interstellar dust. The samples were returned in 2006 via a capsule that detached from the spacecraft and parachuted to the ground at a targeted area in Utah. Mission controllers then placed the still-viable Stardust spacecraft on a flight path that could reuse the flight system, if a target of opportunity presented itself. Tempel 1 became that target of opportunity.

3. “The First Time Ever I Saw Your Face” – The Stardust-NExT mission will allow scientists for the first time to look for changes on a comet’s surface that occurred after one orbit around the sun. Tempel 1 was observed in 2005 by NASA’s Deep Impact mission, which put an impactor on a collision course with the comet. Stardust-NExT might get a glimpse of the crater left behind, but if not, the comet would provide scientists with previously unseen areas for study. In addition, the Stardust-NExT encounter might reveal changes to Tempel 1 between Deep Impact and Stardust-Next, since the comet has completed an orbit around the sun.

4. “The Wind Beneath My Wings” – This Tempel 1 flyby will write the final chapter of the spacecraft’s success story. The aging spacecraft approached 12 years of space travel on Feb. 7, logging almost 6 billion kilometers (3.5 billion miles) since launch. The spacecraft is nearly out of fuel. The Tempel 1 flyby and return of images are expected to consume the remaining fuel.

5. “Love is Now the Stardust of Yesterday” – Although the spacecraft itself will no longer be active after the flyby, the data collected by the Stardust-NExT mission will provide comet scientists with years of data to study how comets formed and evolved.

Do you know the artists names who wrote and sing these celestially romantic tunes ?

NASA Stardust NExT Video: Date with a Comet – Tempel 1

13 Feb 2011 Position of STARDUST-NExT probe
Looking Down on the Sun. This image shows the current position of the STARDUST spacecraft and the spacecraft's trajectory (in blue) around the Sun. Credit: NASA

Latest navigation camera images of Comet Temple 1 coma and surrounding stars.
Taken by Stardust-NExT at about 10:30 a.m. on Feb. 11 – newly obtained from JPL. This region is about 1.2 degrees on a side - 351 x 351 pixels. Exposure duration 10 seconds. These images are crucial for precisely aiming Stardust-NExT. Credit: NASA/JPL

Enlargement of latest navigation camera image of Comet Temple 1 coma and surrounding stars showing a small section around the comet. Taken by Stardust-NExT at about 10:30 a.m. on Feb. 11 – newly obtained from JPL. Exposure duration 10 seconds. These images are crucial for precisely aiming Stardust-NExT. Credit: NASA/JPL

February 13, 2011April 26, 2016 by Anne Minard

Message in a Wobble: Black Holes Send Memos in Light

Where is the Nearest Black Hole — Artist concept of matter swirling around a black hole. (NASA/Dana Berry/SkyWorks Digital)

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Imagine a spinning black hole so colossal and so powerful that it kicks photons, the basic units of light, and sends them careening thousands of light years through space. Some of the photons make it to Earth. Scientists are announcing in the journal Nature Physics today that those well-traveled photons still carry the signature of that colossal jolt, as a distortion in the way they move. The disruption is like a long-distance missive from the black hole itself, containing information about its size and the speed of its spin.

The researchers say the jostled photons are key to unraveling the theory that predicts black holes in the first place.

“It is rare in general-relativity research that a new phenomenon is discovered that allows us to test the theory further,” says Martin Bojowald, a Penn State physics professor and author of a News & Views article that accompanies the study.

Black holes are so gravitationally powerful that they distort nearby matter and even space and time. Called framedragging, the phenomenon can be detected by sensitive gyroscopes on satellites, Bojowald notes.

Lead study author Fabrizio Tamburini, an astronomer at the University of Padova (Padua) in Italy, and his colleagues have calculated that rotating spacetime can impart to light an intrinsic form of orbital angular momentum distinct from its spin. The authors suggest visualizing this as non-planar wavefronts of this twisted light like a cylindrical spiral staircase, centered around the light beam.

“The intensity pattern of twisted light transverse to the beam shows a dark spot in the middle — where no one would walk on the staircase — surrounded by concentric circles,” they write. “The twisting of a pure [orbital angular momentum] mode can be seen in interference patterns.” They say researchers need between 10,000 and 100,000 photons to piece a black hole’s story together.

And telescopes need some kind of 3D (or holographic) vision in order to see the corkscrews in the light waves they receive, Bojowald said: “If a telescope can zoom in sufficiently closely, one can be sure that all 10,000-100,000 photons come from the accretion disk rather than from other stars farther away. So the magnification of the telescope will be a crucial factor.”

He believes, based on a rough calculation, that “a star like the sun as far away as the center of the Milky Way would have to be observed for less than a year. So it is not going to be a direct image, but one would not have to wait very long.”

Study co-author Bo Thidé, a professor and program director at the Swedish Institute of Space Physics, said a year may be conservative, even in the case of a small rotation and a need for up to 100,000 photons.

“But who knows,” he said. “We will know more after we have made further detailed modelling – and observations, of course. At this time we emphasize the discovery of a
new general relativity phenomenon that allows us to make observations, leaving precise quantitative predictions aside.”

Links: Nature Physics

February 12, 2011December 24, 2015 by Steve Nerlich

Astronomy Without A Telescope – Plausibility Check

OK, this looks nice - but let's think it through. You've got two binary stars with angular diameters and spectral properties roughly analogous to our Sun - shining through an atmosphere containing semi-precipitous water vapor (also known as clouds). Plausible? Credit: NASA.

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So we all know this story. Uncle Owen has just emotionally blackmailed you into putting off your application to the academy for another year – and even after you just got those two new droids, darn it. So you stare mournfully at the setting binary suns and…

Hang on, they look a lot like G type stars – and if so, their roughly 0.5 degree angular diameters in the sky suggest they are both only around 1 astronomical unit away. I mean OK, you could plausibly have a close red dwarf and a distant blue giant having identical apparent diameters, but surely they would look substantially different, both in color and brightness.

So if those two suns are about the same size and at about the same distance away, then you must be standing on a circumbinary planet that encompasses both stars in one orbit.

To allow a stable circumbinary orbit – either a planet has to be very distant from the binary stars – so that they essentially act as a single center of mass – or the two stars have to be really close together – so that they essentially act as a single center of mass. It’s unlikely a planet could maintain a stable orbit around a binary system where it is exposed to pulses of gravitational force, as first one star passes close by, then the other passes close by.

Anyhow, if you can stand on a planet and watch a binary sunset – and you are a water-solvent based life form – then your planet is within the star system’s habitable zone where H₂O can exist in a fluid state. Given this – and their apparent size and proximity to each other, it’s most likely that you orbit two stars that are really close together.

To get a planet in a habitable zone around a binary system - your choices are probably limited to circumbinary planets around two close binaries - or circumstellar planets around one star in a widely spread binary. Credit: NASA/JPL.

But, taking this further – if we accept that there are two G type stars in the sky, then it’s unlikely that your planet is exactly one astronomical unit from them – since the presence of two equivalent stars in the sky should roughly double the stellar flux you would get from one. And it’s not a simple matter of doubling the distance to halve the stellar flux. Doubling the distance will halve the apparent diameters of the stars in the sky, but an inverse square relation applies to their brightness and their solar flux, so at double the distance you would only get a quarter of their stellar flux. So, something like the square root of two, that is about 1.4 astronomical units away from the stars, might be about right.

However, this means the stars now need a larger than solar diameter to create the same apparent size that they have in the sky – which means they must have more mass – which will put them into a more intense spectral class. For example, Sirius A has 1.7 times the diameter of the Sun, roughly twice its mass – and consequently about 25 times its absolute luminosity. So even at 2 astronomical units distance, Sirius A would be nearly five times as bright and deliver five times as much stellar flux as the Sun does to Earth (or ten times if there are two such stars in the sky).

So, to sum up…

It’s a struggle to come up with a scenario where you could have two stars in the sky, with the same apparent diameter, color and brightness – unless you are in a circumbinary orbit around two equivalent stars. There’s no reason to doubt that a planet could maintain a stable circumbinary orbit around two equivalent stars, that might be G type Sun analogues or whatever. However, it’s a struggle to come up with a plausible scenario where those stars could have the angular diameter in the sky that they appear to have, while still having your planet in the system’s habitable zone.

I mean OK you’re on a desert world, but two stars of a more intense spectral class than G would probably blow away the atmosphere – and even two G type stars would give you a Venus scenario (which receives roughly double the solar flux that Earth does, being 28% closer to the Sun). They could be smaller K or M class stars, but then they should be redder than they appear to be – and your planet would need to be closer in, towards that range where it’s unlikely your planet could retain a stable orbit.

So, at this point you should call shenanigans.

Further reading: Planets Thrive Around Stellar Twins (includes a permitted screen shot from a certain movie).

February 11, 2011April 26, 2016 by Ken Kremer

NASAs First Orion Capsule Ships for Crucial Deep Space Tests

The Lockheed Martin Orion team at NASA’s Michoud Assembly Facility in New Orleans, La., inspects the first Orion crew module known as the Ground Test Article (GTA) prior to shipping to Lockheed Martin’s Denver facilities. In Denver, the GTA will be integrated with an encapsulating aeroshell to provide thermal protection before undergoing rigorous testing to verify it can withstand the harsh environments of a deep space mission. The aeroshell will complete the exterior of the spacecraft, as depicted in the hanging banner displayed in the upper left. Credit: NASA

[/caption]The first Orion spacecraft has just been shipped from NASAs Michoud Assembly Facility in New Orlean’s to a Lockheed Martin manufacturing facility in Denver for crucial tests to simulate the harsh environment of deep space.

The Orion crew cabin – know as the Ground Test Article or GTA – was shipped by truck and will arrive in Denver on Feb. 14 according to a Lockheed Martin spokesperson.

Orion is NASA’s next generation crew vehicle and will eventually replace the Space Shuttle system after the looming retirement of the three orbiter fleet, now reset to mid 2011.

The Orion crew exploration vehicle is capable of supporting missions to low Earth orbit (LEO), the Moon, Asteroids and Deep Space.

The next step at Denver is to install the heat shield and thermal protection backshell. The pathfinding vehicle will then be subjected to performance testing inside the acoustic and environmental testing chamber. The testing exercise ensures the vehicle can meet the challenges of ascent, on-orbit operations and safe landing.

“This is a significant milestone for the Orion project and puts us on the right path toward achieving the President’s objective of Orion’s first crewed mission by 2016,” said Cleon Lacefield, Lockheed Martin vice president and Orion program manager. “Orion’s upcoming performance tests will demonstrate how the spacecraft meets the challenges of deep-space mission environments such as ascent, launch abort, on-orbit operations, high-speed return trajectory, parachute deployment, and water landings in a variety of sea states.”

Engineers for Lockheed Martin successfully finished the initial construction and testing phase for this prototype Orion crew cabin at New Orleans. The final pieces of the Orion GTA were welded together in late May 2010 using a state of the art friction stir welding process. See photos below from my inspection tour of the newly welded Orion GTA.

The spacecraft underwent proof pressure testing this past fall. Several mass and volume simulators including the parachutes were installed by the technical team to ready the capsule for shipment.

Parachutes are installed by Lockheed Martin technicians on the Orion Ground Test Article (GTA) at NASA’s Michoud Assembly Facility in New Orleans. Credit: NASA

In Denver, the vehicle will be bombarded with acoustic energy and vibrations to simulate flight like situations that correlate the structural environment inside and outside the vehicle. The tests will determine if the spacecraft was properly designed to survive the harsh rigors of spaceflight. Lessons learned will be incorporated into the tools and manufacturing processes that will eventually lead to a human rated production vehicle.

The GTA vehicle will then be transported to NASA’s Langley Research facility for drop tests to simulate, validate and certify a variety of water landing scenarios at the new Hydro Impact Basin. The Langley facility will be used to test and certify water landing for all human-rated spacecraft for NASA according to Lockheed.

NASA and Lockheed hope to launch the first unmanned Orion test flight in 2013 if the budget allows. Construction of the service module and other key components is in progress.

Orion has achieved other significant development milestones in the past year.

Orion GTA crew cabin with crew hatch and windows after final pieces were welded together using state of the art friction stir welding. Credit: Ken Kremer

360 degree panorama of Orion GTA looking inside crew hatch. Credit: nasatech.net

The emergency abort rocket was successfully tested on May 6, 2010 at the U.S. Army’s White Sands Missile Range near Las Cruces, N.M. The abort rocket is bolted atop the crew cabin and is designed to pull the capsule away from the launcher in a split second in an emergency and save astronauts lives.

“The Phase 1 Safety Review was completed in June 2010 and formally acknowledges that Orion’s design meets all of NASA’s critical safety requirements for a human-rated space flight vehicle for flights to low earth orbit (LEO), lunar and deep space missions,” according to Larry Price, Orion Deputy Program Manager at Lockheed Martin.

In the past year the Orion budget has been cut significantly by NASA due to lack of funding from the federal government and the outlook for future funding is uncertain. The new Congress is aiming to cut NASA’s research and development budget even further.

Orion abort rocket mock up on public exhibit at the Kennedy Space Center Visitor Complex in Florida next to Orion crew capsule mockup (at left). The emergency rocket will be bolted atop an Orion spaceship for the initial orbital test flight which is currently slated for a 2013 launch. Credit: Ken Kremer

Lockheed Martin Space Systems Company is the prime contractor for Orion and designed and built the GTA as part of a multiyear contract awarded by NASA worth some $3.9 Billion US Dollars. The goal is to produce a new, US-built manned capsule capable of launching American astronauts into space in the post shuttle era.

As soon as the shuttles are retired – for lack of money – the United States will have no capability to loft American astronauts to the International Space Station (ISS) for at least several years. NASA – and all other ISS partners – will be wholly dependent on the Russian Soyuz capsules for launching astronauts to the ISS until either the Orion or commercially developed space taxis such as the Dragon spacecraft from SpaceX are ready for flight. The first operational unmanned Dragon was test flown in Dec 2010.

The Obama Administration sought to cancel Orion in Feb. 2010 as part of NASA’s Project Constellation Return to the Moon program, but then decided to continue Orion’s development after the cancellation proposal met strong bipartisan opposition in Congress.

Orion was to have been launched atop the Ares 1 rocket which has now been officially cancelled. NASA has started the design of a replacement for the Ares 1 which will most likely be a shuttle derived vehicle. Congress has mandated that the first test flight of the still undefined heavy lift rocket must take place by 2016.

Alternatively, Orion could be launched atop a Delta 4 Heavy booster after the rocket is man-rated.

Orion Crew Vehicle Construction Video

Watch this video to see how the first Orion spacecraft was constructed from pieces at NASA’s Michoud Assembly Facility in New Orleans. Credit: NASA

Orion crew module processing at NASA’s Michoud Assembly Facility in New Orleans. Credit: NASA

Lockheed Martin team of aerospace engineers and technicians poses with Orion GTA after welding into one piece. Credit: Ken Kremer.

360 degree panorama of Orion GTA and Lockheed Martin team. Credit: nasatech.net