FY 2007 Year in Review
The Science Mission Directorate's Input to the President's Space and Aeronautics Report 2007
NASA SMD successfully launched four new space science missions designed to improve our understanding of solar processes, the Earth, and the history of the solar system. Those missions are:
• Time History of Events and Macroscale Interactions during Substorms (THEMIS), successfully launched February 17. It is NASA's first five-satellite mission launched aboard a single rocket. The mission will help resolve the mystery of what triggers geomagnetic substorms which are atmospheric events visible in the Northern Hemisphere as a sudden brightening of the Northern Lights, or aurora borealis. The findings from the mission may help protect commercial satellites and humans in space from the adverse effects of particle radiation. THEMIS' satellite constellation lined up along the sun-Earth line, and began collecting coordinated measurements, and observing substorms. Data collected from the five identical probes will help pinpoint where and when substorms begin, a feat impossible with any previous single-satellite mission.
• Aeronomy of Ice in the Mesosphere (AIM), launched on April 25. This is the first mission dedicated to the exploration of mysterious ice clouds that dot the edge of space in Earth's polar regions. The mission will study clouds that are noctilucent, meaning they can be seen from the ground only at night, when they are illuminated by sunlight no longer visible from the Earth's surface. The first of these noctilucent clouds was observed by AIM on May 25, nearly two weeks before they were visible to observers on the ground.
• The Phoenix mission to Mars blasted off August 4th, aiming for a May 25, 2008, arrival at the Red Planet and a close-up examination of the surface of the northern polar region. Phoenix will be the first mission to touch water-ice on Mars. Its robotic arm will dig to an icy layer believed to lie just beneath the surface. The mission will study the history of the water in the ice, monitor weather of the polar region, and investigate whether the subsurface environment in the far-northern plains of Mars has ever been favorable for sustaining microbial life.
• The Dawn spacecraft began its 3 billion kilometer (1.7 billion mile) journey through the inner solar system to study a pair of asteroids on September 27. Dawn is scheduled to begin its exploration of Vesta in 2011 and Ceres in 2015. The two icons of the asteroid belt are located in orbit between Mars and Jupiter and have been witness to so much of our solar system's history.
NASA and university scientists had made substantial progress understanding the processes governing ice sheets and sea ice in the Arctic and Antarctic regions. A team of NASA and university scientists has found clear evidence that extensive areas of snow melted in west Antarctica in January 2005 in response to warm temperatures. This was the first widespread Antarctic melting ever detected with NASA's QuikScat satellite and the most significant melt observed using satellites during the past three decades. The affected regions encompass a combined area as big as California. Changes in the ice mass of Antarctica, Earth's largest freshwater reservoir, are important to understanding global sea level rise. Large amounts of Antarctic freshwater flowing into the ocean also could affect ocean salinity, currents and global climate. The 2005 melt was intense enough to create an extensive ice layer when water refroze after the melt. However, the melt was not prolonged enough for the melt water to flow into the sea.
In another study, scientists using NASA satellites discovered an extensive network of waterways beneath a fast-moving Antarctic ice stream that provide clues as to how "leaks" in the system impact sea level and the world's largest ice sheet. This exciting discovery of large lakes exchanging water under the ice sheet surface radically altered scientists view of what is happening at the base of the ice sheet and how ice moves in that environment.
In yet another NASA study found that in 2005 the Arctic replaced very little of the thick sea ice it normally loses and replenishes each year. Replenishment of this thick, perennial sea ice each year is essential to the maintenance and stability of the Arctic summer ice cover. Using satellite data from NASA's QuikScat and other data, scientists studied six annual cycles of Arctic perennial ice coverage from 2000 to 2006. The scatterometer instrument on QuikScat sends radar pulses to the surface of the ice and measures the echoed radar pulses bounced back to the satellite. These measurements allow scientists to differentiate the seasonal ice from the older, perennial ice. The scientists found that after the 2005 summer melt, only about four percent of the nearly 965,000 square miles of thin, seasonal ice that formed the previous winter survived the summer and replenished the perennial ice cover. That was the smallest replenishment seen in the study. As a result, perennial ice coverage in January 2006 was about 14 percent smaller than the previous January.
NASA satellite data helped scientists solve a decades-old puzzle about how vast blooms of microscopic plants can form in the middle of otherwise barren mid-ocean regions. The research team published findings in May that used the data to show that episodic, swirling current systems known as eddies act to pump nutrients up from the deep ocean to fuel such blooms. Data sets came from NASA's TOPEX/Poseidon, Jason, Aqua and QuikSCAT satellites. The fate of all of that biomass also is important, as plankton blooms can remove substantial amounts of carbon dioxide from surface waters and sink it to the deep ocean. The plants in the bloom either die and sink when the bloom runs its course or are consumed by animals, which then make fecal pellets that drop to the sea floor.
In July, NASA's Tropical Composition, Cloud and Climate Coupling (TC4) field campaign began in San Jose, Costa Rica, with an investigation into how chemical compounds in the air are transported vertically into the stratosphere and how that transport affects cloud formation and climate. The campaign was an unprecedented opportunity to use NASA's complete suite of satellite and airborne Earth-observing capabilities to investigate a largely unexplored region of the atmosphere. Soaring high above the cloud systems was a NASA ER-2 aircraft, which can reach an altitude of 70,000 feet, or 3 miles into the stratosphere. A NASA WB-57 aircraft flew into the cirrus clouds and sample the chemical make-up of the storm systems’ outflow. NASA's DC-8 aircraft probed the region between the troposphere and the stratosphere (known as the tropopause transitional layer) with remote-sensing instruments. It also sampled cloud particles and air chemistry at lower altitudes. Weather radar and meteorological balloons were deployed in Panama to support the campaign. Additional balloons were launched from Costa Rica and San Cristobal Island in the Galapagos Archipelago. Observations from seven satellites complemented the aircraft measurements with large-scale views of many different features of the atmosphere. For example, the Aura spacecraft focused on the chemical composition of the tropopause transitional layer and measure ozone, water vapor, carbon monoxide and particles. NASA's Aqua satellite mapped thin cirrus clouds, some of which are so faint they are nearly invisible to the naked eye. Instruments on the CALIPSO and CloudSat satellites pierced the atmosphere to provide vertical profiles of clouds and aerosol particles that can change how clouds form.
According to a report published in mid February, based on some of the first observations by NASA's Mars Reconnaissance Orbiter, liquid or gas flowed through cracks penetrating underground rock on Mars. These fluids may have produced conditions to support possible habitats for microbial life. These ancient patterns were revealed when the most powerful telescopic camera ever sent to Mars began examining the planet last year. The camera showed features as small as approximately 3 feet across.
During 2007, after having explored Mars for three-and-a-half years in what were missions originally designed for three months, NASA's Mars rovers faced perhaps their biggest challenge as severe storms blanketed mars. The rovers faced dusty winds, power starvation and other challenges -- and survived. Now they are back to doing groundbreaking field work on Mars.
A patch of Martian soil analyzed by NASA's rover Spirit is so rich in silica that it may provide some of the strongest evidence yet that ancient Mars was much wetter than it is now. The processes that could have produced such a concentrated deposit of silica require the presence of water. It also reinforces the fact that significant amounts of water were present in Mars' past, which continues to spur the hope that we can show that Mars was once habitable and possibly supported life.
NASA’s New Horizons spacecraft came to within 1.4 million miles of Jupiter on Feb. 28, using the planet's gravity to trim three years from its travel time to Pluto. For several weeks before and after this closest approach, the piano-sized robotic probe trained its seven cameras and sensors on Jupiter and its four largest moons, storing data from nearly 700 observations on its digital recorders and gradually sending that information back to Earth. These new views included the closest look yet at the Earth-sized "Little Red Spot" storm churning materials through Jupiter's cloud tops; detailed images of small satellites herding dust and boulders through Jupiter's faint rings; and of volcanic eruptions and circular grooves on the planet's largest moons.
In August, scientists from the Cassini-Huygens mission announced they may have identified the source of one of Saturn's more mysterious rings. Saturn’s rings are an enormous, complex structure, and their origin is a mystery. Saturn's “G ring” likely is produced by relatively large, icy particles that reside within a bright arc on the ring's inner edge. The plasma in the giant planet's magnetic field sweeps through this arc continually, dragging out the fine particles, which create the G ring. The finding is evidence of the complex interaction between Saturn's moons, rings and magnetosphere. Studying this interaction is one of the mission’s objectives. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency.
Instruments on NASA's Cassini spacecraft also found evidence for seas, likely filled with liquid methane or ethane, in the high northern latitudes of Saturn's moon Titan. One such feature is larger than any of the Great Lakes of North America and is about the same size as several seas on Earth. Titan is the second largest moon in the solar system and is about 50 percent larger than Earth's moon.
NASA's twin Solar Terrestrial Relations Observatory (STEREO) spacecraft made the first three-dimensional images of the sun. The new view will greatly aid scientists’ ability to understand solar physics and thereby improve space weather forecasting. STEREO's depth perception also will help improve space weather forecasts. Of particular concern is a destructive type of solar eruption called a Coronal Mass Ejection (CME). CMEs are eruptions of electrically charged gas, called plasma, from the sun's atmosphere. A CME cloud can contain billions of tons of plasma and move at a million miles per hour.
In April, one of the STEREO satellites captured the first images of a collision between a comet and a solar hurricane. The phenomenon was caused by a coronal mass ejection, a large cloud of magnetized gas cast into space by the sun. The collision resulted in the complete detachment of the plasma tail of Encke’s comet. Observations of the comet reveal the brightening of its tail as the coronal mass ejection swept by and the tail's subsequent separation as it was carried away by the front of the ejection.
A new technique using the Solar and Heliospheric Observatory (SOHO) now enables scientists to forecast solar radiation storms, giving future astronauts, traveling to the moon and Mars, time to seek shelter and ground controllers time to safeguard satellites. The new method for the first time offers as much as one hour advance notice when a storm is approaching. Spacecraft and satellites would also benefit. Subatomic particles striking computer processors and other electronics can cause onboard computers to suddenly reboot or issue nonsense commands. If a satellite operator knows that a storm is coming, the craft can be placed in a protective "safe mode" until the storm passes.
SOHO is a project of international cooperation between the European Space Agency and NASA.
Astronomers using NASA's Hubble Space Telescope announced in May that they have discovered a ghostly ring of dark matter that formed long ago during a titanic collision between two galaxy clusters. Dark matter makes up most of the universe's material. Ordinary matter, which makes up stars and planets, comprises only a small percent of the universe's matter. The ring's discovery was among the strongest evidence yet that dark matter exists. Astronomers have long suspected the existence of the invisible substance and theorized that it is the source of additional gravity that holds galaxy clusters together. Also using Hubble, an international team of astronomers created the first three-dimensional map of the large-scale distribution of dark matter in the universe. This new map provides the best evidence to date that normal matter, largely in the form of galaxies, accumulates along the densest concentrations of dark matter.
The brightest stellar explosion ever recorded may be a long-sought new type of supernova, according to observations by NASA's Chandra X-ray Observatory and ground-based optical telescopes. This discovery indicates that violent explosions of extremely massive stars were relatively common in the early universe, and that a similar explosion may be ready to go off in our own galaxy. Astronomers think many of the first generation of stars were this massive, and this new supernova may thus provide a rare glimpse of how the first stars died. It is unprecedented, however, to find such a massive star and witness its death.
In August, NASA's Galaxy Evolution Explorer spotted a surprisingly long comet-like tail behind a star streaking through space at supersonic speeds. The star, named Mira after the Latin word for "wonderful," has been a favorite of astronomers for approximately 400 years. It is a fast-moving, older red giant that is shedding massive amounts of surface material. The space-based Galaxy Evolution Explorer scanned the popular star during its ongoing survey of the entire sky in ultraviolet light. Astronomers then noticed what looked like a comet with a gargantuan tail. Material blowing off Mira is forming a wake 13 light-years long, or about 20,000 times the average distance of Pluto from the sun. Nothing like this has been seen before around a star.
NASA's Spitzer Space Telescope captured the light, for the first time, from two known planets orbiting stars other than our sun. The findings announced in March mark the beginning of a new age in planetary science, in which extrasolar planets can be directly measured and compared. All confirmed extrasolar planets, including the two recently observed by Spitzer, have been indirectly discovered. They were discovered mainly by the "wobble" technique and more recently, the "transit" technique. In the first method, a planet is detected by the gravitational tug it exerts on its parent star, which makes the star wobble. In the second, a planet's presence is inferred when it passes in front of its star, causing the star to dim, or blink. Both strategies use visible-light telescopes and reveal the mass and size of planets.