Sara’s note: Please join us in welcoming our newest guest blogger, Dr. Dan Wik! You might have heard our interview with Dan in our podcast NASA’s Newest X-Ray Eyes, and we’re excited to get more behind-the-scenes coverage of NuSTAR and Dan’s research in his blog posts.
Imagine you are usually confined inside your home – like we are on the surface of the Earth – but when you do make it outside at night, you forget your glasses despite having terrible vision. Looking up at the sky, you can see a few blurry stars and a diffuse glow, but you can’t tell if the glow is really diffuse or just made up of many fainter stars. Next time you make it outside, you resolve to remember your glasses to find out. If the light is coming from the X-ray part of the spectrum, then on the next trip outside you’ll be wearing a pair of NuSTARs.
NuSTAR is the first observatory capable of focusing the bluest colors of X-ray light, in a bandwidth where the X-ray sky is the brightest. Since its launch last summer, it has been surveying the sky in order to detect the source of this glow, which is thought to be made up of many discrete objects. These are not stars, but massive black holes in the hearts of galaxies billions of light years away. In fact, we’ve already resolved the redder part of the X-ray sky with the Chandra X-ray Observatory, which is how we know what these objects are. However, the kind of black holes we see with Chandra cannot produce the light at the bluest end of the X-ray spectrum. We still think they’re massive black holes, but there’s something intrinsically different about them. Once we find them with NuSTAR, we’ll learn exactly why they’re different and what that means for the growth of black holes over cosmic time. These massive black holes at the centers of galaxies – millions of times more massive than the Sun – appear to grow as the galaxy around them grows and changes, a process that depends on their galactic neighborhoods and the larger cosmic web — seeded just after the Big Bang — in which all galaxies are ensnared.
A model of NuSTAR at Caltech. The part closest to the camera holds the mirrors (the two “eyes” – looks remarkably like a face), and the detectors and rest of the spacecraft are on the far end of the boom. Credit: Caltech/JPL/NASA
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Each December, there’s a bit of a lull in astronomy news. Not only do the holidays slow things down, but astronomers are also getting ready for the winter meeting of the American Astronomical Society (AAS) in January. These AAS meetings (there’s also a summer meeting in May or June) are a particularly high-profile place to announce a groundbreaking discovery or other exciting piece of research – scientists are surrounded by their peers, with press conferences held daily throughout the week-long meeting. We’ve covered a few of these meetings in the past – you can learn more about AAS press conferences, follow Maggie’s adventures at the 2011 AAS meeting in Seattle, or even listen to our podcast from a meeting in 2010.
This year’s AAS winter meeting was held in Long Beach, CA, where astronomers got a bit of sunshine and sand as well as time to meet with their colleagues, present their research, and hear about the latest and greatest astronomy news. We wanted to share some of the highlights from the astrophysics press releases – and there are some particularly exciting ones in this meeting’s batch!
Credit: NASA, ESA, and A. Feild (STScI)
From a “zombie” to a “rogue” – the astronomy community still can’t get enough of the strange planet Fomalhaut b! First, there was controversy over whether it was a planet or a dust cloud, and now they’re looking at the planet’s unusual orbit within the debris disk of its host star, Fomalhaut. The planet’s highly elliptical, 2,000-year orbit leads astronomers to suspect that there may be other planet-like bodies hiding within the debris around Fomalhaut. One or more of these other bodies may have gravitationally disturbed Fomalhaut b, ejecting it from a position closer to the star and sending it on a wild and potentially destructive orbit through the debris disk. I’m sure this isn’t the last we’ve heard about Fomalhaut b, as astronomers are hoping to continue the hunt for other planets in its system, and to better understand its own characteristics.
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Transcript (Text, PDF)
It’s an exciting experience for any space geek to watch a new satellite launch into orbit. Even through an online video feed, it’s thrilling to see something that Earthlings worked for years to create headed for its new home, to be our newest eyes on the Universe. These launches don’t happen so often, especially for astrophysics missions, where we see the launch of a new observatory every few years at most. Earlier in 2012, we were excited about the launch of NuSTAR, a small explorer X-ray mission collaboratively created by teams at Caltech, NASA, and over a dozen other institutions around the world.
NuSTAR advances the international astronomical community’s ability to observe some of the hottest, densest, and most energetic objects in the Universe. Its detectors are sensitive at significantly higher energies than other X-ray observatories such as Chandra and XMM-Newton, giving astronomers a chance to extend the range of data they collect. During its mission lifetime, NuSTAR will conduct a survey for massive black holes, study the particles accelerated in active galaxies, and observe the remnants of exploded stars and the chemical elements they’ve left behind.
We were interested to find out more about NASA Goddard’s involvement in the mission, so we interviewed post-doc Dr. Dan Wik about his work with the satellite’s optics and his interest in observing galaxy clusters with NuSTAR.
Credit: Dan Wik
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Curiosity has successfully made it to Mars! While it’s gotten a generous amount of press in recent days, we wanted add our own nod to the successful landing of the Mars Science Laboratory aboard its rover, Curiosity, (after its Seven Minutes of Terror) at 1:32 a.m. EDT, Aug. 6, 2012 (10:32 p.m. PDT on Aug. 5, 2012). Since then it has proceeded with its set up to get itself fully up and running in order to study the red planet.
The rover, launched Nov. 26, 2011, hosts a myriad of instruments that will allow it to analyze the martian landscape. The Mars Science Laboratory (MSL) is about the size of a small SUV and carries with it three cameras, several spectrometers, as well as radiation detectors, environmental sensors, and atmospheric sensors. This mission is part of NASA’s Mars Exploration Program, a long-term effort of robotic exploration of the red planet. Curiosity was designed to assess whether Mars ever had an environment able to support small life forms called microbes. In other words, its mission is to determine the planet’s “habitability.” The rover will analyze samples scooped from the soil and drilled from rocks. The record of the planet’s climate and geology is essentially written in the rocks and soil — in their formation, structure, and chemical composition. The rover’s onboard laboratory will study rocks, soils, and the local geologic setting in order to detect chemical building blocks of life (e.g., forms of carbon) on Mars and will assess what the martian environment was like in the past. We look forward to all that we can learn about Mars from the MSL aboard Curiosity.
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Voyager is soon to be the first man-made object to leave the solar system. Data from NASA’s Voyager 1 spacecraft indicate that this deep space explorer has entered a region in space where the number of charged particles from beyond our solar system has significantly increased. This could mean that Voyager 1 may be at the edge of our solar system and about to leave it. The spacecraft Voyagers 1 and 2 were launched in 1977, originally designated to study Jupiter and Saturn, but have since continued their journey on to study the outer solar system. The image above depicts where the Voyager spacecraft are in relation to our solar system and the surrounding area.
The Voyager team is looking at a few specific things that they expect will tell them when the spacecraft has punched through the ‘heliosheath’ – a kind of bubble around our solar system where stellar winds slow down dramatically. First, a great increase in the number of galactic cosmic rays (energetic charged particles from outside our solar system). The numbers appear to be on the rise, which is a good sign that Voyager 1 is getting close to the heliosheath. The team is also looking at the intensity of energetic particles from inside the heliosphere. These have been steadily decreasing but have yet to drop off abruptly, as would be expected when the craft leaves the heliosphere. Lastly, there is the measurement of the direction of the magnetic field lines surrounding the spacecraft. Currently, while the craft remains in the heliosphere, the field lines run east-west. However, when it passes into interstellar space, it is thought that the field lines will switch to running more north-south. There is still much analysis of the data to be done, but we can still expect that one day Voyager will be our first man-made ambassador to interstellar space.
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The NuSTAR (Nuclear Spectroscopic Telescope Array) launched last week, with a mission goal of studying black holes and their jets of energy, as well as other high-energy objects in our universe (supernovae, compact stars after their explosive deaths, and clusters of galaxies). This is done through using a very unique observatory to study X-ray light. Since NuSTAR focuses X-rays, it requires a long focal length, so the optics must be far away from each other (to achieve a 10 meter focal length). This is done via a unique detector system, optics, and deployable mast, shown in the figure below.
As we were watching for updates on the launch of the NuSTAR satellite, I discovered a pleasant surprise. I am a scientist at Goddard in the Astrophysics Science Division (Code 665 to those of you familiar with the code system at GSFC), however, I spend the bulk majority of my time in The Optics Lab here at Goddard Space Flight Center, running my experimental tests of dust grain analogs on equipments that the engineers in the Optics Branch (Code 551) use to test the transmission and reflection properties of different materials. This ranges from coating for new mirrors, to the transmission properties of just about any material you can think of. The head of my lab, Manuel Quijada, is a can-do-it-all guru of materials, and has allowed me to help out on samples that are not necessarily part of my scientific work, but are great for training and very cool to observe unique optical properties with. He informed me that the NuSTAR mirrors were heated at Goddard in another lab, and then sent here, to our lab, for cutting and polishing, as well as testing to ensure the best mirrors were used for the NuSTAR spacecraft. This work was done by a co-op in the Optics Branch, Javier Del Hoyo, who is still here in the lab today. The mirrors, with their unique curvature required for measurements (see the figures below), underwent multiple inspections and testing to ensure they were top quality, then were shipped to Danish Technical University-Space in Copenhagen to be coated with a material suitable for measurements at X-ray wavelengths (Pt/SiC and W/SiC), and then sent to Columbia University, where the precision assemblage of the optics occurred.
The slumped glass posts are prepared for heating (figure courtesy of M. Quijada and J. Del Hoyo)
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We posted once about NuSTAR, a new X-ray telescope. It was due to be launched in March, but that launch date is now scheduled for June. Below is a great new image of NuSTAR in the nose cone of the Pegasus rocket it will be launched on.
Using NASA’s Galaxy Evolution Explorer, a space-based observatory, and the Pan-STARRS1 telescope on the summit of Haleakala in Hawaii, astronomers have gathered the most direct evidence yet
of a supermassive black hole shredding a star that wandered too close.
Credit: NASA, S. Gezari (The Johns Hopkins University), and J. Guillochon (University of California, Santa Cruz)
“When the star is ripped apart by the gravitational forces of the black hole, some part of the star’s remains falls into the black hole while the rest is ejected at high speeds,” said project lead Suvi Gezari of the Johns Hopkins University. “We are seeing the glow from the stellar gas falling into the black hole over time. We’re also witnessing the spectral signature of the ejected gas, which we find to be mostly helium. It is like we are gathering evidence from a crime scene. Because there is very little hydrogen and mostly helium in the gas, we detect from the carnage that the slaughtered star had to have been the helium-rich core of a stripped star.”
The above image and this video are computer simulations:
The video shows a star being shredded by the gravity of a massive black hole. As the video caption says, “Some of the stellar debris falls into the black hole and some of it is ejected into space at high speeds. The areas in white are regions of highest density, with progressively redder colors corresponding to lower-density regions. The blue dot pinpoints the black hole’s location. The elapsed time corresponds to the amount of time it takes for a Sun-like star to be ripped apart by a black hole a million times more massive than the Sun.”
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Meet the Nuclear Spectroscopic Telescope Array or NuSTAR – a new X-ray telescope that’s being launched in March of 2012. Below is the actual telescope in its pre-launch configuration:
And here is what it will look like post-launch!
NuSTAR has an interesting design that includes a deployable mast, which is used to extend the observatory to its full 10 meter focal length. Because this mast will flex slightly as the spacecraft orbits, NuSTAR employs a laser measurement system to monitor the degree of motion of the mirrors relative to the detectors.
NuSTAR will survey high-energy X-ray emission from black holes, help determine how chemical elements are cooked up in supernova explosions, and find new, previously unknown high energy sources. Gorgeous Chandra X-ray Observatory imagery has been done at relatively low X-ray energies – NuSTAR will extend the energy range of X-ray images by nearly a factor of 10, via breakthroughs in detector technology and X-ray optics.
You can read more at the HEASARC Picture of the Week and on the NuStar website. For education and outreach about NuSTAR, try the Caltech site.