Tuesday, June 26, 2012

Cassini Shows Why Jet Streams Cross-Cut Saturn

Turbulent jet streams, regions where winds blow faster than in other places, churn east and west across Saturn. Scientists have been trying to understand for years the mechanism that drives these wavy structures in Saturn's atmosphere and the source from which the jets derive their energy.

In a new study appearing in the June edition of the journal Icarus, scientists used images collected over several years by NASA's Cassini spacecraft to discover that the heat from within the planet powers the jet streams. Condensation of water from Saturn's internal heating led to temperature differences in the atmosphere. The temperature differences created eddies, or disturbances that move air back and forth at the same latitude, and those eddies, in turn, accelerated the jet streams like rotating gears driving a conveyor belt.

A competing theory had assumed that the energy for the temperature differences came from the sun. That is how it works in the Earth's atmosphere.

"We know the atmospheres of planets such as Saturn and Jupiter can get their energy from only two places: the sun or the internal heating. The challenge has been coming up with ways to use the data so that we can tell the difference," said Tony Del Genio of NASA's Goddard Institute for Space Studies, N.Y., the lead author of the paper and a member of the Cassini imaging team.

The new study was possible in part because Cassini has been in orbit around Saturn long enough to obtain the large number of observations required to see subtle patterns emerge from the day-to-day variations in weather. "Understanding what drives the meteorology on Saturn, and in general on gaseous planets, has been one of our cardinal goals since the inception of the Cassini mission," said Carolyn Porco, imaging team lead, based at the Space Science Institute, Boulder, Colo. 

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

Saturday, June 9, 2012

NASA readies to Hunt Black Holes with New Space Telescope

Nasa Black Hole Hunter
The U.S. space group is set to launch a telescope into space June 13 to seek out and learn black holes -- those still-mysterious space bodies that scientists consider lie at the spirit of every massive galaxy, including our own Milky Way.

Black holes have a gravitational pull so intense that not even light can flee from them. As gas, dust and stars are sucked in; the fabric accelerates and heats up, generating powerful X-ray beam emissions.

NASA is setting out to conduct a survey of the black holes in the universe. 

The U.S. space organization is launching a black hole seeker, a new telescope called NuSTAR, but properly known as Nuclear Spectroscopic Telescope Array. 

Paul Hertz is the director of NASA's astrophysics division. "Stars, nebulae and black holes emit X-rays of the type that we use in medical X-rays, and these cannot be detected from the outside of the Earth," explained Hertz.

Current telescopes offer images that show a universal glow from hundreds of massive black holes. NASA expects NuSTAR will be able to offer far improved images of black holes and other high-energy events when it surveys the extra-galactic sky.

NuSTAR launches, it will organize a 10-meter pole that will divide its mirrors from its detectors. That pole provides the distance required to focus the X-ray light into sharp images. 

Monday, June 4, 2012

SpaceX journey should get NASA moving

A space capsule known as the Dragon touched down in the Pacific Ocean on Thursday.

After launching into orbit May 22, the capsule had performed a sequence of complicated exercises, docked with the International Space Station, dropped off more than 1,000 pounds of provisions and returned home bearing a load of science experiments.

It was the first profitable spacecraft to complete such an achievement. And the company that developed it, Space Exploration Technologies Corp., or SpaceX, was satisfied with a U.S. government agreement of $1.6 billion to fly 12 more supply missions.

Optimists saw a quick private company leveraging public investment, reducing prospect taxpayer burdens and heralding a new age of profitable space flight.

SpaceX’s accomplishment is inspiring, and private venture seems likely to transport much-needed competence to the government’s space program. The problem is that, even if this new company delivers all its promised benefits, U.S. space policy will still have no clear objective. In spite of many setbacks, SpaceX looks like a comparatively good deal for taxpayers.

Elon Musk, the company’s billionaire founder, says its missions will charge one-eighth what space ferry flights did, and a study last year by the National Aeronautics and Space Administration set up that SpaceX spent far less than what NASA would have to expand the rocket that launched the Dragon capsule. Ambitiously, the company aims to take humans into space by 2015.

Sunday, June 3, 2012

ISS Transit of Venus


In 1768, when James Cook sailed out of Plymouth harbor to observe the Transit of Venus in Tahiti, the trip was tantamount to a voyage through space. The remote island had just been "discovered" a year earlier, and by all accounts it was as strange and alien to Europeans as the stars themselves. Cook's pinpoint navigation to Tahiti and his subsequent observations of Venus crossing the South Pacific sun in 1769 have inspired explorers for centuries.

 One of those explorers is about to beat Cook at his own game.

High above Earth, astronaut Don Pettit is preparing to photograph the June 5th Transit of Venus from space itself.

 Because transits of Venus come in pairs that occur once every 100 years or so, humans have rarely had the chance to photograph the apparition from Earth, much less from Earth orbit.

"The Expedition 31 crew will be the first people in history to see a Venus transit from space, and Pettit will be the first to photograph one," says Mario Runco, Jr. of the Johnson Space Center (JSC). Runco, an astronaut himself who flew aboard three shuttle missions, is an expert in the optics of spacecraft windows. Along with his wife Susan Runco, who is the coordinator for astronaut photography at JSC, Mario is helping Pettit gather the best possible images of the transit.

Pettit will be pointing his camera through the side windows of the space station's cupola, an ESA-built observatory module that provides a wide-angle view of Earth and the cosmos. Its seven windows are used by the crew to operate the station's robotic arm, coordinate space dockings, and take science-grade photos of the Earth and sky. It's also a favorite "hangout" for off-duty astronauts who find the view exhilarating.

Pettit describes the camera system: "I'll be using a high-end Nikon D2Xs camera and an 800mm lens with a full-aperture white light solar filter."

This month's transit is the bookend of a 2004-2012 pair. Astronauts were onboard the ISS in 2004, but they did not see the transit, mainly because they had no solar filters onboard. Tiny Venus covers a small fraction of the solar disk, so the sun is still painfully bright to the human eye even at mid-transit. Pettit's foresight to bring a solar filter with him makes all the difference.