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There’s a NuSTAR in town

June 11th, 2012 Comments off

This guest post by Geeked on Goddard friend, Andy Ptak, is about an exciting new X-ray astronomy mission that’s about to be launched.

What is NuSTAR?
This week NASA plans to launch its next X-ray astrophysics satellite, NuSTAR.  X-rays are where really exotic stuff in the Universe shines, like black holes, supernovae explosions (massive stars blowing themselves up) and really, really hot gas (millions of degrees or hotter).

But it is very hard to focus X-rays.  As any card-carrying astronomer would tell you, you focus X-rays in the same way you skip a rock on a lake (we risk getting our X-ray astronomer card taken away if we don’t use that analogy).  Normally an X-ray photon would go right through a mirror just like tossing a rock would splash into water.  But if it hits at a slight angle, the X-ray will bounce off.

NuSTAR will be the first satellite to focus astrophysical X-rays at highest X-ray energies, some roughly at the same energy as those used in medical X-rays.  Scientists and technicians at Goddard helped make the glass used for the NuSTAR mirrors, and several of us went up to Nevis Labs (part of Columbia University in New York) to help with the testing of the mirrors once they were completed last year.

A problem with focusing X-rays is that it means you need to keep the mirror and detector far apart, especially if you want to focus very energetic X-rays.  NuSTAR is also designed to be very inexpensive (by satellite standards) so it needs to be able to fit in a small launcher.  The solution to this is that it has a nifty extendible mast, as shown in this video.

Normally NASA engineers don’t like moving parts on satellites, because they might get stuck (the moving parts, not the engineers).  But even they would probably admit it looks cool when NuSTAR is extending its mirrors (the shiny metal-plated thingees) away from the detectors (on the main body of the spacecraft).

A technical challenge is that once extended, that mast will “flap around like a wet noodle”, as one senior NASA scientist put it. This isn’t directly because the satellite will be moving from target to target (called slewing). It’s because as NuSTAR moves in and out of the Earth’s shadow, the change in temperature of the mast will induce some motion. This motion is very slight, but enough to mess with the images that NuSTAR is taking.  To get around this a laser system is installed on NuSTAR.  The laser is attached to the mirror module and shines down near the X-ray detectors.  By tracking how the spot made by the laser moves we can track how the optics and detectors are moving relative to each other.  This might sound like a band-aid fix (because it is) but it is a lot cheaper than moving up to a larger launcher.

Waiting for Launch
Since building something like NuSTAR literally is rocket science, it is not surprising that there are occasionally launch delays.  All systems have recently passed flight readiness reviews and NuSTAR is planned for launch on June 13.  NuSTAR is going to launch from a rocket called Pegasus that is first dropped from an airplane. You can watch the launch coverage online.

Right now one of the main roles of GSFC scientists is to help test the software that will be used to analyze NuSTAR observations.  A slight silver lining to the launch delay is that it gives us more time to do this and to get more practice with simulated data.  This will put is in a better position to analyze the real data when it comes.  And with NASA satellites, once the data starts coming it really does quickly feel like drinking from a fire hose, so the more practice we have the better.

— Andy Ptak

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OH AND DID I MENTION? All opinions and opinionlike objects in this blog are mine alone and NOT those of NASA or Goddard Space Flight Center. And while we’re at it, links to websites posted on this blog do not imply endorsement of those websites by NASA.

A behind-the-scenes peek at the Apollo Command Module scale model at the NASA Goddard Visitor Center

April 2nd, 2012 Comments off

Recent, gogblog went to visit the life-size model of the Apollo Command Module in the rocket garden behind the Goddard Visitor Center. Amidst the hardware of the historic Aerobee and Delta launch systems dating to the dawn of the space age, Visitor Center program manager Bill Buckingham gave us an exclusive tour of command module model — a pretty good replica of the object that carried three humans to the moon back in the 60s.

The funnest part was squirming into the thing and getting a feel, literally, for the environment in which three full-grown men spent a week traveling to and from the Moon: working, eating, sleeping, and defecating in a space the size of a large closet. It gives you a new appreciation for the meaning of the word “hero.” I call that “Three men doing their business in a closet for a week.”

The command module model, among the most popular attractions at the Visitor Center, is feeling its age. Water seepage has taken its toll, and Bill is hoping to attract contributions from volunteers to restore the model to better shape. Here’s what Bill has to say about it.


New slideshow: Featured NASA images set to an excerpt from “Earth” by One Ring Zero

March 14th, 2012 Comments off


The New York City indie band One Ring Zero is a friend of gogblog. Band cofounder Michael Hearst kindly gave us blanket permission to use the band’s music in slideshows and videos. Here is the latest: a sampling of “featured images” from the NASA/Goddard Sciences and Exploration Directorate website: sciences.gsfc.nasa.gov. It’s set to an excerpt from ORZ’s composition Earth, which is in the band’s “Planets” CD.

In a previous video featuring ORZ’s music, we celebrated the Hubble Space Telescope’s one millionth scientific observation. I like to think that the success of that piece in the blogosphere owed as much to ORZ’s music as the stunning Hubble pix.

 

Reader mail: How far do black hole bullets blast out into space?

January 30th, 2012 Comments off

As I reported on January 10, on or about June 3, 2009, enormous blobs of hot electrically charged matter were ejected from a black hole at about a quarter of the speed of light — roughly 75 million meters per second. Astronomers used a globe-spanning network of telescopes to observe the event, which occurred in a star system called H1743–322, about 28,000 light-years from Earth. A team of scientists reported the observations at the most recent meeting of the American Astronomical Society in Austin, Texas.

Geeked On Goddard reader John Conway contacted us with this excellent question:

“Interesting article. My thought: Do these “bullets” of gas dissipate over distance traveled, or do they keep going into space? If they were to come into contact with another celestial body, star, planet, black hole, whatever, what might be the result?”

I asked one of the astronomers who observed the goings-on at the black hole, James Miller-Jones, to explain.

“As the bullets move away from the black hole, they expand gradually,” Miller-Jones said. “Think of a bullet of material moving down a cone, whose apex is at the black hole.  If you take a slice through the cone to get a circular cross-section, that cross section gets bigger as you move away from the black hole. In the same way, the bullets are expanding as they move outwards.

“However, just because the bullets are too faint to detect doesn’t mean they have dissipated. They keep moving outwards, sweeping up or pushing aside the rarefied interstellar gas that is in the path of the bullets.Once they have swept up an amount of gas with a rest mass energy equal to their own initial energy (kinetic plus rest mass energy), they will slow down.”



And what would happen to a planet or star that got in the path of the bullets? Miller-Jones says it depends how close the object lies. In a binary star system (like H1743–322), the black holes co-orbits a nearby companion star, sucking gas off its surface. If the black-hole bullets hit the nearby star, “they would be expected to blast material off the surface of the donor.”

For more distant objects, the effect of the impact would be correspondingly less.

Then I asked Miller-Jones to estimate how far the bullets travel, and how fast. For example, if a black hole were located at the center of our solar system, how far outward would the bullets travel? Beyond Pluto? Beyond the distant shell of comets (the Kuiper belt) encircling the solar system? Or beyond the boundaries of the solar system to the vast space between our sun and the next star?

“We tracked these bullets way beyond [the distance from our sun to Pluto], and even beyond the Kuiper belt. Our last measurement put them about 120 times the sun-Earth distance from the black hole (120 astronomical units, or AU), whereas the Kuiper belt goes out to about 55 AU.

“In terms of how far the bullets travel before we can no longer detect them, that depends very much on the opening angle of the cone (how “wide” or “narrow” it is), the original energy of the outburst, and on how far away the source was.  With our most sensitive telescopes, and with the brightest bullets from the brightest black hole outbursts, we’ve tracked them out to about 0.1-0.2 light years from the black hole.  But we have no reason to think that they stopped there.”



Miller-Jones said that a blast of black-hole bullets would quickly leave the boundaries of its home solar system and enter interstellar space. For something like the bullets he and his colleagues studied, it would take them just a few days to exit a solar system about the size of ours, moving at about 25 percent of the speed of light.

Thanks to John Conway for his great questions.

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OH AND DID I MENTION? All opinions and opinionlike objects in this blog are mine alone and NOT those of NASA or Goddard Space Flight Center. And while we’re at it, links to websites posted on this blog do not imply endorsement of those websites by NASA.




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Why did a black hole blast star stuff into space at a quarter of light-speed on June 3, 2009? Here is what happened

January 10th, 2012 3 comments

On June 3, 2009, in an X-ray binary star system far, far away. . .


We know the what of the extraordinary event that occurred in May 2009 around a distant black hole; we just don’t know the why of it, although the possibilities are pretty amazing.

At the 2012 American Astronomical Society (AAS) meeting in Austin, Texas, Gregory Sivakoff of the University of Alberta in Canada reported some astounding observations he and his colleagues accomplished using a globe-spanning array of radio telescopes and two NASA satellites.

The whole episode was a cosmic stroke of luck: The light from an event that happened some 28,000 years ago reached Earth just days before the global collaboration was scheduled to open for business. Goddard astrophysics writer Francis Reddy explains the details of the science today in a web feature story and animation.

Let’s start with the what: On or about June 3, 2009, enormous blobs of hot electrically charged matter were ejected from a black hole at about a quarter of the speed of light — roughly 75 million meters per second.

Next, the where: These black-hole “bullets,” as Reddy calls them in his web feature, were ejected from a binary star system. Called H1743–322, the  system lies about 28,000 light-years from Earth. NASA’s HEAO-1 satellite discovered it in 1977

In H1743–322, a black hole and a star orbit each other at close quarters, every few days. They are close enough that the black hole’s massive gravity draws a steady stream of material off its companion’s wispy surface. The hot electrically charged gas swirls around the edge of the black hole, forming a whirlpool-like “accretion disc.” As the gas accelerates to high speed, it radiates X-rays that satellites at Earth can detect.

“Some of the infalling matter becomes re-directed out of the accretion disk as dual, oppositely directed jets,” Reddy writes. “Most of the time, the jets consist of a steady flow of particles. Occasionally, though, they morph into more powerful outflows that hurl massive gas blobs at significant fractions of the speed of light.”

Years ago, Sivakoff’s colleague James Miller-Jones, currently based at the International Center for Radio Astronomy Research at Curtin University in Perth, Australia, conceived of a plan to mount a “multiwavelength campaign” to study the periodic outbursts that astronomers observe from X-ray binaries like H1743–322. They got their chance on May 22, 2009.

On that date, renewed activity around the black hole triggered the Burst Alert Telescope on NASA’s Swift satellite. Miller-Jones, Sivakoff, and the other members of the international team of observers were able to marshal three radio telescopes: the Very Long Baseline Array, the Very Large Array, and the Australia Telescope Compact Array. The team also drew on data from NASA’s Rossi X-ray Timing Explorer (RXTE) satellite (which was just switched off this week, by the way, after 16 years of meritorious service).

Using information from the telescopes and satellites, the scientists were able to reconstruct the events leading up to and following the ejection of black-hole bullets from the binary system. Sivakoff reported those findings today at the AAS meeting.

Now, finally, what about the “how” of this outburst? That’s not very clear yet.

In similar black hole binaries, Miller-Jones says, astronomers have measured ejections traveling 92 percent of the speed of light!  What process can shoot giant blobs of stuff out of the accretion zone of a black hole at such incredible speeds?

Sivakoff sketches out one possible explanation: Imagine knots of mass in the accretion disc, swirling around, getting closer and closer to the black hole. The disc is looped by powerful magnetic fields, which twist and tangle together as the disc rotates. When magnetic flux lines cross and connect, it could release enough energy to boost the black-hole bullets up and out of the disk.

“I think of a fairly stiff rope that is firmly to attached to the accretion disc,” Sivakoff explains. “As the disc spins, the rope is wound up, forming a sort of helix. Of course, there’s not one but many such ropes in an accretion disc. If two of those ropes touch — what astronomers call magnetic reconnection — lots of energy can be released. I like to envision ‘crossing the streams,’ a la Ghost Busters. This energy can accelerate particles, launching the bullet.”

There is another scenario, Miller-Jones says. Some scientists have proposed that what actually happens is that the inner edge of the accretion disc constricts, edging closer to the black hole’s “event horizon,” beyond which matter cannot escape. The magnetic and gravitational forces at this border region are extremely intense.

The forces could unleash a surge of material into the black hole’s paired jets, with a wavelike shock front ahead of it. “This causes particle acceleration,” Miller-Jones says, “and hence bright radio emission at this shock front.” So the bullets may actually be sudden surges in the jets, not discrete blobs.

But these explanations are just informed speculation at the moment. Additional multi-telescope observations could eventually provide enough clues to untangle the extreme physics that power black-hole bullets.

The team can only hope their recent stroke of luck holds out. Sivakoff says that the H1743–322  system conveniently started to flare up in late May 2009 — just as the team was preparing for the official opening of their observing window.

“Technically our observing was supposed to start in June 2009,” Sivakoff says. “But when this outburst went off a few days before our window was supposed to open up, we actually got permission to start observing earlier.”

So the discovery was the team’s inaugural run. “This was quite a trial by fire,” Sivakoff says.


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OH AND DID I MENTION? All opinions and opinionlike objects in this blog are mine alone and NOT those of NASA or Goddard Space Flight Center. And while we’re at it, links to websites posted on this blog do not imply endorsement of those websites by NASA.


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What was that piece of space junk that fell in Namibia?

December 23rd, 2011 1 comment

This 30 kg titanium pressurant tank, which survived the reentry of a Delta 2 rocket second stage, looks very similar to the metal sphere found in Namibia.

 



The coolest thing about working at NASA’s Goddard Space Flight Center is that you are surrounded by people you can ask questions like, “Hey, what was that metal ball sphere that fell out of outer space into a lake in Namibia?

One such individual is my friend Scott Hull, who is an orbital debris engineer at Goddard. He helps scientists and engineers comply with NASA regulations regarding space debris, including how to minimize the volume of it in orbit and reducing the chance to nil that a chunk of it will bonk somebody on the head someday. (That’s never happened, by the way…)

I asked Scott about that mysterious sphere in Namibia, reported on CNN.com and Space.com, among other places. He things the object in question looks like a propulsion tank — a tank that held fuel for rocket thrusters on a spacecraft.  He says it’s “probably titanium, since it has no discernible rust or burn-through spots. Tanks like this survive reentry relatively frequently.”

Indeed, that is why NASA engineers have begun to develop “demisable” propellant tanks for satellites and spacecraft, which burn up on reentry. Think of demisable rocket fuel tanks as like “biodegradable” plastic of aerospace engineering. When you are done with them, they despose of themselves.

“If this technology can be adapted for other uses, we may see fewer of these tanks surviving reentry,” Hull emailed me. “Of course, the tanks that are already on-orbit will still be falling for decades, so there will always be some.”

He pointed out that the tank found in Namibia looks very similar to the third example on this NASA web site.

Why didn’t the tank burn up? One possibility is that it’s wrapped with graphite epoxy or glass fibers. That provides some resistance to heat, presumably.

There you have it, straight from the Orbital Debris Engineer’s mouth. If you want to learn more about space debris and Scott’s work, see past coverage in Geeked On Goddard here, here, and here.
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OH AND DID I MENTION? All opinions and opinionlike objects in this blog are mine alone and NOT those of NASA or Goddard Space Flight Center. And while we’re at it, links to websites posted on this blog do not imply endorsement of those websites by NASA.




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Comet Lovejoy from the space station: spectacular!

December 23rd, 2011 Comments off






International Space Station Commander Dan Burbank captured spectacular imagery of Comet Lovejoy as seen from about 240 miles above the Earth’s horizon on Wednesday, Dec. 21. Burbank described seeing the comet as “the most amazing thing I have ever seen in space,” in an interview with WDIV-TV in Detroit. MORE

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OH AND DID I MENTION? All opinions and opinionlike objects in this blog are mine alone and NOT those of NASA or Goddard Space Flight Center. And while we’re at it, links to websites posted on this blog do not imply endorsement of those websites by NASA.




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Christian Ready’s video explainer about exoplanet Kepler 22b

December 22nd, 2011 3 comments

My friend Christian Ready, a web developer who used to work on the Hubble Space Telescope mission, has made a clear, well-paced, and visually captivating explainer video about “the discovery of Kepler 22b, a planet orbiting a star not unlike our own sun at a distance where life can thrive.” (This is the finding that was announced BEFORE the more recent announcement of Kepler 20e and 20f, Earth-sized planets that are not in the so-called “habitable zone” of their star.) You can see other videos by Christian on his YouTube channel.





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OH AND DID I MENTION? All opinions and opinionlike objects in this blog are mine alone and NOT those of NASA or Goddard Space Flight Center. And while we’re at it, links to websites posted on this blog do not imply endorsement of those websites by NASA.




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New Comet Lovejoy video from SDO/SOHO Picture of the Week

December 21st, 2011 Comments off



Steele Hill, NASA Goddard’s herald of all things heliospheric, just posted his latest  release of imagery, courtesy of NASA’s Solar Dynamics Observatory (SDO) and the Solar and Heliospheric Observatory (SOHO). Steele creates these images and videos for display in science museums and other public places. The video and image in this post combined solar imagery from both SDO and SOHO of the rounding of the sun by Comet Lovejoy last week. Steele’s  descriptive text (below) explains the details.

And by the way, Steele and his colleagues have just surpassed their 500th solar “Picture of the Week.” It took 10 years. Congratulations!

“Comet Lovejoy came into view on Dec. 14 as a bright, white streak, skimmed across the Sun’s edge about 140,000 km above the surface late Dec. 15 and early Dec. 16, 2011, furiously brightening and vaporizing as it approached the Sun. It exited our field of view on Dec. 18. It was the brightest sun-grazing comet that SOHO had ever seen, with a nucleus about twice as wide as a football field. It unexpectedly survived the pass and cruised out from behind the Sun some hours later. Comets are ancient balls of dust and ice.

“In this still and movie, we combine views from SOHO’s two different coronagraphs (which block out the Sun) with solar Dynamics Observatory’s view of the Sun itself.  Note how the tail of the comet always turns away from the Sun due to the forces of the solar wind.”






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OH AND DID I MENTION? All opinions and opinionlike objects in this blog are mine alone and NOT those of NASA or Goddard Space Flight Center. And while we’re at it, links to websites posted on this blog do not imply endorsement of those websites by NASA.




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Earth Science Picture of the Day: December 21, 2011

December 21st, 2011 Comments off

In July 2010, Geeked on Goddard marked the 10th anniversary of the Earth Science Picture of the Day (EPOD), a social media site founded at Goddard Space Flight Center.

EPOD is still going strong. Here is today’s Earth Science Picture of the Day, a beautiful multiple-image composite of the moon rising above the Parthenon in Athens.

Photographer: Elias Chasiotis; Mona Sorayaei
Summary Author: Elias Chasiotis; Mona Sorayaei

The image sequence above shows the partially eclipsed Moon rising over the Parthenon in Athens, Greece on December 10, 2011. Philopappou Hill, the hill opposite to the Acropolis, offered an interesting perspective to capture this lunar eclipse. Totality was noted in Australia and most of Asia as well as portions of western North America. Totality was not visible in Greece, where the full Moon rose after the Earth’s shadow had already covered the lunar disk. Nevertheless, the partial phase of the eclipse was quite attention getting. This was the last total lunar eclipse until April 2014.






About EPOD
The Earth Science Picture of the Day (EPOD) was started at Goddard Space Flight Center in 2000 by scientist James Foster of Goddard’s Hydrological Sciences Laboratory and is a collaboration with Universities Space Research Association (USRA). USRA’s Stacy Bowles handles the technical aspects of the site with help from Erin Carver. Stu Witmer does the editing and runs the EPOD Facebook page.

Since its launch in September 2000, the Earth Science Picture of the Day (EPOD) website has provided a forum for professional photographers, educators, scientists, students and the general public to share images that highlight Earth Science processes and phenomena. To date, there are well over 3000 user-submitted images and educational summaries representing the full spectrum of Earth Science.

Each year EPOD receives more than twice as many submissions as can be published. Submissions are reviewed for scientific accuracy, topic relevance, and aesthetic appeal before publication. Further, EPOD receives more 2 million visits (worldwide) resulting in over 4 million page views each year. Web analytics also reveal that in addition to a loyal U.S. and Canadian audience, EPOD reaches viewers in 205 other countries and territories.

Visit the EPOD website if you would like to contribute your Earth photography to the project.
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OH AND DID I MENTION? All opinions and opinionlike objects in this blog are mine alone and NOT those of NASA or Goddard Space Flight Center. And while we’re at it, links to websites posted on this blog do not imply endorsement of those websites by NASA.


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