Thursday, April 26, 2012

Dragon Expected to Set Historic Course

In response to SpaceX's announcement that it has delayed launch of its Falcon 9 rocket and Dragon spacecraft from April 30 to May 7, NASA issued the following statement from Associate Administrator for Human Exploration and Operations William Gerstenmaier:

"We appreciate that SpaceX is taking the necessary time to help ensure the success of this historic flight. We will continue to work with SpaceX in preparing for the May 7 launch to the International Space Station."

As scheduled, the mission will be the first to see a privately built and funded spacecraft rendezvous with the station. If successful, the mission is expected to pave the way toward regular operational commercial cargo missions.

"It's almost like the lead-up to Apollo, in my mind," said Mike Horkachuck, NASA's project executive for SpaceX. "You had Mercury then you had Gemini and eventually you had Apollo. This would be similar in the sense that, we're not going to the moon or anything as spectacular as that, but we are in the beginnings of commercializing space. This may be the Mercury equivalent to eventually flying crew and then eventually leading to, in the long run, passenger travel in space."

California-based Space Exploration Technologies, known as SpaceX, is preparing to launch an ambitious mission to dock its Dragon spacecraft to the space station and return it to Earth. The spacecraft will not have a crew, but will carry about 1,200 pounds of cargo that the astronauts and cosmonauts living on the station will be able to use. The capsule will go into space atop a Falcon 9 rocket also built by SpaceX.

Elon Musk, the owner of SpaceX and the company's chief designer, said his team is not taking the mission's objectives for granted, particularly since both the Dragon spacecraft and Falcon 9 rocket are relatively new to spaceflight.

"We have launched the rocket twice and the spacecraft once so they are pretty new, and the proximity operations will be our first test in space," Musk said following the Flight Readiness Review. "I think it’s important to appreciate that this is fairly tricky and it is important to remember that we are hitting a target within a few inches while it moves over 17,000 mph."

Because the mission is a test flight, the cargo is not material deemed critical to the crew, Horkachuck said. Launch is targeted for May 7 from Space Launch Complex 40 at Cape Canaveral Air Force Station in Florida, within sight of the launch pads the space shuttles used to carry the station's components into orbit. There also are several tests and reviews coming up later this month similar to those performed ahead of space shuttle missions.

If this mission is successful, the Dragon is expected to become operational and launch regular supply runs to the station. Unlike any other cargo carrier, the Dragon can bring things back to Earth, too, a boon for scientists whose research is taking place on the orbiting laboratory.

SpaceX already has two successful Falcon 9 launches to its credit, along with a history making demonstration of the Dragon capsule that in December 2010, became the first privately built and operated spacecraft to be launched to and recovered from Earth orbit.

"I think the (first demonstration) mission was more of a question mark in my mind," Horkachuck said, "because no capsule that these guys had built before had gone into space, done the basic maneuvering to show you have attitude control as well as re-entering, so knowing the vehicle came through re-entry relatively unscathed and all the parachute systems worked perfectly, that was a real big deal."

Because of that mission's achievements, NASA and SpaceX agreed to combine the planned second and third demonstration flights into one. Assuming the Dragon spacecraft passes about a few days' worth of equipment checks and demonstration in orbit, it will be allowed to approach the station close enough for astronauts to grab the Dragon with the station's large robotic arm. The arm will berth the capsule to the station and astronauts will unload the spacecraft and put about 1,400 pounds of material inside the Dragon for return to Earth.

Monday, April 23, 2012

NASA Spacecraft Reveals Recent Geological Activity on the Moon

New images from NASA's Lunar Reconnaissance Orbiter (LRO) spacecraft show the moon's crust is being stretched, forming minute valleys in a few small areas on the lunar surface. Scientists propose this geologic activity occurred less than 50 million years ago, which is considered recent compared to the moon's age of more than 4.5 billion years.

A team of researchers analyzing high-resolution images obtained by the Lunar Reconnaissance Orbiter Camera (LROC) show small, narrow trenches typically much longer than they are wide. This indicates the lunar crust is being pulled apart at these locations. These linear valleys, known as graben, form when the moon's crust stretches, breaks and drops down along two bounding faults. A handful of these graben systems have been found across the lunar surface.

"We think the moon is in a general state of global contraction because of cooling of a still hot interior," said Thomas Watters of the Center for Earth and Planetary Studies at the Smithsonian's National Air and Space Museum in Washington, and lead author of a paper on this research appearing in the March issue of the journal Nature Geoscience. "The graben tell us forces acting to shrink the moon were overcome in places by forces acting to pull it apart. This means the contractional forces shrinking the moon cannot be large, or the small graben might never form."

The weak contraction suggests that the moon, unlike the terrestrial planets, did not completely melt in the very early stages of its evolution. Rather, observations support an alternative view that only the moon's exterior initially melted forming an ocean of molten rock.

In August 2010, the team used LROC images to identify physical signs of contraction on the lunar surface, in the form of lobe-shaped cliffs known as lobate scarps. The scarps are evidence the moon shrank globally in the geologically recent past and might still be shrinking today. The team saw these scarps widely distributed across the moon and concluded it was shrinking as the interior slowly cooled.

Based on the size of the scarps, it is estimated that the distance between the moon's center and its surface shrank by approximately 300 feet. The graben were an unexpected discovery and the images provide contradictory evidence that the regions of the lunar crust are also being pulled apart.

"This pulling apart tells us the moon is still active," said Richard Vondrak, LRO Project Scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "LRO gives us a detailed look at that process."

As the LRO mission progresses and coverage increases, scientists will have a better picture of how common these young graben are and what other types of tectonic features are nearby. The graben systems the team finds may help scientists refine the state of stress in the lunar crust.

"It was a big surprise when I spotted graben in the far side highlands," said co-author Mark Robinson of the School of Earth and Space Exploration at Arizona State University, principal investigator of LROC. "I immediately targeted the area for high-resolution stereo images so we could create a three-dimensional view of the graben.

Wednesday, April 18, 2012

Cassini Successfully Flies over Enceladus

These raw, unprocessed images of Saturn's moons Enceladus and Tethys were taken on April 14, 2012, by NASA's Cassini spacecraft.

Cassini flew by Enceladus at an altitude of about 46 miles (74 kilometers). This flyby was designed primarily for the ion and neutral mass spectrometer to analyze, or "taste," the composition of the moon's south polar plume as the spacecraft flew through it. Cassini's path took it along the length of Baghdad Sulcus, one of Enceladus' "tiger stripe" fractures from which jets of water ice, water vapor and organic compounds spray into space. At this time, Baghdad Sulcus is in darkness, but that was not an obstacle for another instrument, the composite infrared spectrometer, which can see features by their surface temperatures and which also took measurements during this flyby.

As soon as daylight passed into the spacecraft's remote sensing instruments' line of sight, Cassini's cameras acquired images of the surface. The wide-angle-camera image included in the new batch, taken from around the time of closest approach, has some smearing from the movement of the spacecraft during the exposure, but still shows the surface in vivid detail.

Cassini's cameras also imaged Enceladus' south polar plume at a high phase angle as the satellite appeared as a thin crescent and the plume was backlit.

After the Enceladus encounter, Cassini passed the moon Tethys with a closest approach distance of about 5,700 miles (9,100 kilometers). This was Cassini's best imaging encounter with Tethys since a targeted encounter in September 2005. The 2005 encounter, with a closest approach distance of about 930 miles (1,500 kilometers), provided the images of Tethys with the best resolution and captured views of the side of Tethys that faces Saturn in its orbit. This new encounter examined the opposite side of Tethys, providing some of the highest-resolution images of the side that faces away from Saturn. Cassini acquired a 22-frame mosaic of this side, which features the large impact basin named Odysseus. Scientists will use these new data in conjunction with images from previous encounters to create digital elevation maps of the moon's surface.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory in Pasadena manages the mission for the agency's Science Mission Directorate in Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations team is based at the Space Science Institute in Boulder, Colo. JPL is a division of Caltech. 

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Monday, April 16, 2012

Hubble Sees Messier 70: Tight and Bright

In this image, the NASA/ESA Hubble Space Telescope has captured the brilliance of the compact center of Messier 70, a globular cluster. Quarters are always tight in globular clusters, where the mutual hold of gravity binds together hundreds of thousands of stars in a small region of space. Having this many shining stars piled on top of one another from our perspective makes globular clusters a popular target for amateur skywatchers and scientists alike.

Messier 70 offers a special case because it has undergone what is known as a core collapse. In these clusters, even more stars squeeze into the object's core than on average, such that the brightness of the cluster increases steadily towards its center.

The legions of stars in a globular cluster orbit about a shared center of gravity. Some stars maintain relatively circular orbits, while others loop out into the cluster's fringes. As the stars interact with each other over time, lighter stars tend to pick up speed and migrate out toward the cluster's edges, while the heavier stars slow and congregate in orbits toward the center. This huddling effect produces the denser, brighter centers characteristic of core-collapsed clusters. About a fifth of the more than 150 globular clusters in the Milky Way have undergone a core collapse.

Although many globular clusters call the galaxy's edges home, Messier 70 orbits close to the Milky Way's center, around 30 000 light-years away from the Solar System. It is remarkable that Messier 70 has held together so well, given the strong gravitational pull of the Milky Way's hub.

Messier 70 is only about 68 light-years in diameter and can be seen, albeit very faintly, with binoculars in dark skies in the constellation of Sagittarius (The Archer). French astronomer Charles Messier documented the object in 1780 as the seventieth entry in his famous astronomical catalogue.

This picture was obtained with the Wide Field Camera of Hubble’s Advanced Camera for Surveys. The field of view is around 3.3 by 3.3 arcminutes. 

Tuesday, April 03, 2012

NASA probe to hunt galactic hearts of darkness

Black holes, neutron stars and supernova remnants won't be able to hide in the fog of space for much longer.

NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) mission — which is due to launch this spring, though the agency has yet to pin down a date — will pierce the dust and gas shrouding sources of high-energy X-rays, revealing many secrets they have long managed to conceal, scientists say.

Although telescopes such as NASA's Chandra X-ray Observatory have probed the skies with X-rays before, these other instruments have focused on lower-energy bands.

"NuSTAR is going to be the first focusing high-energy X-ray telescope," said mission principal investigator Fiona Harrison of the California Institute of Technology.

Extreme events
The NuSTAR mission's increased sensitivity will allow it to probe the hearts of other galaxies for some of their most violent and mysterious objects, such as black holes.

Black holes form when a dying star collapses in on itself. As the stellar remnant becomes smaller and more dense, its gravitational pull becomes so strong that not even light can escape.

But as dust and gas fall inward, friction and other forces heat the material to millions of degrees. The resulting X-rays, detectable to NuSTAR, should allow astronomers to calculate how fast black holes are spinning, and understand more about how they formed, researchers say.

Some material also shoots away from black holes in jets approaching the speed of light. The accelerated particles can vary in brightness over the course of time, and NuSTAR will be able to study how they change.

While NuSTAR will study some black holes in distant galaxies, it will also make observations closer to home.

"There is a black hole that's 4 million times the mass of the sun at the heart of the Milky Way," Harrison told "It doesn't emit a lot of radiation, for reasons that are somewhat mysterious."

Occasionally, black holes "burp" or "hiccup," giving off a burst of radiation for unknown reasons. Observing the black hole in the high-energy X-ray spectrum should provide more clues about how this local black hole works, researchers say.