Monday, August 29, 2011

Aquarius Rising

In mythology and astrology, Aquarius is known as the water-bearer. For NASA, Aquarius is the space agency's first new Earth-watching tool—actually, water-watching—since 2008.

At 7:20:13 a.m. Pacific Daylight Time on June 10, 2011, the Aquarius/SAC-D observatory was launched on a Delta II rocket from Vandenberg Air Force Base in California. About an hour later, the satellite separated from the rocket's second stage, established communication with ground controllers, and unfurled its solar arrays. Initial reports showed the observatory to be in excellent health, and operators will spend the next few weeks maneuvering it into a polar orbit and turning on the sensors.

The satellite is a joint project of Argentina's Comision Nacionale de Actividades Espaciales. NASA's Jet Propulsion Laboratory and NASA's Goddard Space Flight Center. The full name of the spacecraft is the Satellite de Aplicaciones Scientifics-D, or SAC-D. Aquarius is a key instrument that will make NASA's first space observations of the salt content, or salinity of the ocean.

Salinity has traditionally been measured from ships and robotic ocean sensors. Aquarius will map the open ocean once every seven days for at least three years, allowing scientists to make the first global maps of salinity in the surface layer. Observing changes in salinity helps scientists understand ocean circulation and currents, the global water cycle and other fundamental features of the seas.

Super Typhoon Nanmadol


Nanmadol formed as a tropical depression over the western Pacific Ocean on August 22, 2011. It strengthened to a tropical storm a day later, and by August 26, it was a super typhoon.The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured this natural-color image of Super Typhoon Nanmadol at 12:50 p.m. Manila time on August 26, 2011. The eye of the storm appears east of the northern Philippines, and Nanmadol spans hundreds of kilometers.

As of 11:00 p.m. Manila time on August 26, 2011, the U.S. Navy’s Joint Typhoon Warning Center (JTWC) reported that Nanmadol had maximum sustained winds of 135 knots (250 kilometers, or 155 miles, per hour) and gusts up to 165 knots (305 kilometers, or 190 miles, per hour). The storm was located roughly 585 nautical miles (1,085 kilometers, or 675 miles) south-southwest of Kadena Air Base, Japan. The storm was forecast to continue traveling toward the north-northwest before turning toward the northeast.

On August 26, 2011, the Associated Press reported that at least one person in the Philippines was missing and several towns in the northern Philippines were flooded by heavy rains from the slow-moving storm.

Thursday, August 25, 2011

NASA's Mission Finds First Trojan Asteroid Sharing Earth's Orbit

Astronomers studying observations taken by NASA's Wide-field Infrared Survey Explorer (WISE) mission have discovered the first known "Trojan" asteroid orbiting the sun along with Earth.

Trojans are asteroids that share an orbit with a planet near stable points in front of or behind the planet. Because they constantly lead or follow in the same orbit as the planet, they never can collide with it. In our solar system, Trojans also share orbits with Neptune, Mars and Jupiter. Two of Saturn's moons share orbits with Trojans.

Scientists had predicted Earth should have Trojans, but they have been difficult to find because they are relatively small and appear near the sun from Earth's point of view.

"These asteroids dwell mostly in the daylight, making them very hard to see," said Martin Connors of Athabasca University in Canada, lead author of a new paper on the discovery in the July 28 issue of the journal Nature. "But we finally found one, because the object has an unusual orbit that takes it farther away from the sun than what is typical for Trojans. WISE was a game-changer, giving us a point of view difficult to have at Earth's surface."

The asteroid is roughly 1,000 feet (300 meters) in diameter. It has an unusual orbit that traces a complex motion near a stable point in the plane of Earth's orbit, although the asteroid also moves above and below the plane. The object is about 50 million miles (80 million kilometers) from Earth. The asteroid's orbit is well-defined and for at least the next 100 years, it will not come closer to Earth than 15 million miles (24 million kilometers).