With more than a few stamps on its passport, NASA's Aquarius instrument on the Argentinian Satélite de Aplicaciones Científicas (SAC)-D spacecraft will soon embark on its space mission to "taste" Earth's salty ocean.

After a journey of development and assembly through NASA facilities, a technology center in Bariloche, Argentina, and testing chambers in Brazil, the Aquarius instrument, set to measure the ocean's surface salinity, recently made the trip from São José dos Campos, Brazil, to California's Vandenberg Air Force Base for final integration and testing before its scheduled launch on June 9.

Aquarius will map the concentration of dissolved salt at the ocean's surface, information that scientists will use to study the ocean's role in the global water cycle and how this is linked to ocean currents and climate. Sea surface temperature has been monitored by satellites for decades, but it is both temperature and salinity that determine the density of the surface waters of the ocean. Aquarius will provide fundamentally new ocean surface salinity data to give scientists a better understanding of the density-driven circulation; how it is tied to changes in rainfall and evaporation, or the melting and freezing of ice; and its effect on climate variability.

"The ocean is essentially Earth's thermostat. It stores most of the heat, and what we need to understand is how do changes in salinity affect the 3-D circulation of the ocean," said Gene Feldman, Aquarius Ground System and Mission Operations Manager at NASA's Goddard Space Flight Center, Greenbelt, Md.

The development of the Aquarius mission began more than 10 years ago as a joint effort between Goddard and NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. In 2008, Goddard engineers completed the Aquarius microwave radiometer instrument, which is the key component for measuring salinity from space.

"The radiometer is the most accurate and stable radiometer built for sensing of Earth from space. It's a one-of-a-kind instrument," said Shannon Rodriguez-Sanabria, a microwave communications specialist at Goddard.

JPL built Aquarius' scatterometer instrument, a microwave radar sensor that scans the ocean's surface to measure the effect wind speed has on the radiometer measurements. The radiometer and scatterometer instruments, along with an 8.25-by-10-foot elliptical antenna reflector and many other systems, have been integrated together at JPL to form the complete Aquarius instrument. A number of other instruments aboard the SAC-D spacecraft are contributions from Argentina, France, Canada and Italy.

In June 2009, Aquarius was flown via a U.S. Air Force cargo jet to San Carlos de Bariloche, Argentina, a destination known for its natural scenery of blue lakes and verdant mountains, to be integrated with Argentina's SAC-D spacecraft. A year later, the fully assembled spacecraft and all the instruments now referred to as the "Aquarius/SAC-D Observatory" were shipped to Brazil. There, engineers began a nine-month campaign of alignment, electro-magnetic, vibration, and thermal vacuum testing to ensure it will survive the rigors of launch and orbiting in space.

JPL will manage the Aquarius mission through Aquarius' commissioning phase, scheduled to last 45 days after launch. Goddard will then manage the Aquarius instrument operations during the mission. Argentina's Comisión Nacional de Actividades Espaciales (CONAE) will operate the spacecraft and download all of the data collected by Aquarius several times per day. Goddard is responsible for producing the Aquarius science data products. JPL will manage the data archive and distribution to scientists worldwide.

Aquarius will collect data continuously as it flies in a near-polar orbit and circles Earth 14 to 15 times each day. The field of view of the instrument is 390 kilometers (242 miles) wide, and will provide a global map every seven days. The data will be compiled to generate more accurate monthly averages during the mission, which is designed to last a minimum of three years.

For more information visit http://www.nasa.gov/topics/earth/features/aquarius20110406.html

Astronomers have discovered that two symmetrical jets shooting away from opposite sides of a blossoming star are experiencing a time delay: knots of gas and dust from one jet blast off four-and-a-half years later than identical knots from the other jet.

The finding, which required the infrared vision of NASA's Spitzer Space Telescope, is helping astronomers understand how jets are produced around forming stars, including those resembling our sun when it was young.

"More studies are needed to determine if other jets have time delays," said Alberto Noriega-Crespo of NASA's Spitzer Science Center at the California Institute of Technology in Pasadena, who is a co-author of the new study to be published in the April 1 issue of Astrophysical Journal Letters. "Now we know that in at least one case, there appears to be a delay, which tells us that some sort of communication may be going on between the jets that takes time to occur."

Jets are an active phase in a young star's life. A star begins as a collapsing, roundish cloud of gas and dust. By ejecting supersonic jets of gas, the cloud slows down its spinning. As material falls onto the growing star, it develops a surrounding disk of swirling material and twin jets that shoot off from above and below the disk, like a spinning top.

Once the star ignites and shines with starlight, the jets will die off and the disk will thin out. Ultimately, planets may clump together out of material left in the spinning disk.

The discovery of the time delay, in the jets called Herbig-Haro 34, has also led the astronomers to narrow in on the size of the zone from which the jets originate. The new Spitzer observations limit this zone to a circle around the young star with a radius of 3 astronomical units. An astronomical unit is the distance between our sun and Earth. This is about 10 times smaller than previous estimates.

"Where we stand today on Earth was perhaps once a very violent place where high-velocity gas and dust were ejected from the disk circling around our very young sun," said Alex Raga of the Universidad Nacional Autónoma de México, the first author of the paper. "If so, the formation of planets like Earth depends on how and when this phenomenon ended. Essentially, every star like our own sun has gone through a similar cloud-disk-jets formation process."

One of the jets in Herbig-Haro 34 had been studied extensively for years, but the other remained hidden behind a dark cloud. Spitzer's sensitive infrared vision was able to pierce this cloud, revealing the obscured jet in greater detail than ever before. Spitzer images show that the newfound jet is perfectly symmetrical to its twin, with identical knots of ejected material.

This symmetry turned out to be key to the discovery of the jets' time delay. By measuring the exact distances from the knots to the star, the astronomy team was able to figure out that, for every knot of material punched out by one jet, a similar knot is shot out in the opposite direction 4.5 years later. This calculation also depended on the speed of the jets, which was known from previous studies by NASA's Hubble Space Telescope. Other symmetrical jets similar to Herbig-Haro 34 have been observed closely before, but it is not clear if they are also experiencing time delays.

The astronomers say that some kind of communication is going on between the Herbig-Haro 34 jets, likely carried by sound waves. Knowing the length of the time delay and the speed of sound allowed them to calculate the maximum size of the jet-making zone.

The astronomy team is currently analyzing other jets imaged by Spitzer, looking for more evidence of time delays.

The Spitzer observations were made before it used up its liquid coolant in May 2009 and began its warm mission.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington.

For more information visit http://www.nasa.gov/mission_pages/spitzer/news/spitzer20110316.html