Jupiter is one of the most studied astronomical objects. Jupiter is by far the largest planet in our Solar System, with more than twice the mass of all the other planets combined. In fact, it has 318 times the mass of the Earth. It's one of the brightest objects in the night sky and people have been studying it since before anyone knew what planets were. Galileo first examined Jupiter with a telescope and discovered four of its moons in 1610. Since that time, thousands of astronomers have studied the mysterious planet. Radio emissions from Jupiter were detected in the 1950s. Scientists soon realized that Jupiter had an enormous magnetic field where trapped electrons and protons spiraled back and forth, producing radio waves called synchrotron emission. Voyager 1 and Voyager 2 flew by Jupiter in 1979 and the Galileo spacecraft orbited Jupiter from 1995 to 2003, sending a probe into the giant planet to study its atmosphere and returning a steady stream of data about the giant planet and the entire Jovian system. Ulysses used Jupiter's enormous gravitational pull for an assist to change its trajectory into an orbit over the Sun's poles and Cassini gave us more data as it flew by Jupiter in 2000 on the way to Saturn.
Even though we know a lot about Jupiter, in many ways it still remains a mystery. It has more than 60 moons and several rings. Scientists have plotted the orbits of the moons and studied the rings. We've found tantalizing hints of liquid water below the icy surface of Jupiter's moon Europa but we don't yet know if it could harbor life. We've discovered volcanoes on Io's surface and deduced how stresses from Jupiter's enormous gravity are heating that fiery Jovian satellite.
Jupiter presents a fascinating set of mysteries for scientists to unravel and in many ways it is the key to understanding our Solar System and how planets form. Over the coming decade, scientists will answer many of the questions posed by our Solar System's largest planet. GAVRT students will be part of the science team making important contributions as we solve fundamental puzzles posed by the mysterious giant, which dominates our planetary neighborhood.
While radio observations on Uranus began in the 1960s, this initial GAVRT campaign began during the summer of 2002. Uranus experienced seasonal changes as it approached its equinox in 2007. The Uranus Campaign is a collaboration of observations of the planet that include the Hubble Space Telescope, the W.M. Keck Observatory, Lowell Observatory, NASA's Infrared Telescope Facility, the Very Large Array (VLA), and GAVRT Program. The VLA and the GAVRT students are contributing the radio measurements. GAVRT observations will help determine the nature of seasonal change in Uranus' deep atmosphere. These studies of Uranus and its seasons will continue for years as one year on Uranus is equal to 84 Earth years!
Quasar Variability Study (QVS)
This study focuses on some of the oldest known objects in our Universe, quasars. Quasars or quasi-stellar objects appear to resemble point sources of light like stars, but their radiation emission is much more intense. The typical quasar puts out more energy each second than our Sun does in 200 years. What is the source of this intense energy emission? Scientists believe it to be supermassive black holes many times the mass of our Sun. The QVS Campaign involves students collecting data on these objects. The initial module focuses on quasars that are "winking" or scintillating and explores the effects of the interstellar medium on this scintillation process. Teamed with GAVRT students and teachers in schools across the globe, we can use DSS-12 to build an extended-time set of data on selected quasars showing significant variability, thereby laying the groundwork for meaningful interpretation of our data. As we add our new data to the growing database, it will allow us to examine and consider these periods of fluctuation, ourselves. Students and scientists alike will benefit by this mutual collaboration, teamed together in the on-going endeavor of science - to hold in the infinite complexity of our minds an understanding of an infinite Universe.
Active Galactic Nuclei (AGN) is a term that refers to galaxies that have excess visible light coming from their nuclei beyond the sum total of visible light from all their central stars. More luminous AGN are called quasars where the nucleus often outshines the host galaxy! The present model is that the excess light is generated by supermassive black holes (millions to billions of times the mass of our sun) that are at the centers of many galaxies. Black holes themselves don't generate any light since by definition a black hole is an object that has a high mass concentrated in a small volume (called the event horizon) where the escape velocity is the speed of light. Since nothing can travel faster than the speed of light, no light escapes the black hole.
The region around a black hole outside the event horizon is different. As gas falls toward the black hole, it heats up and starts emitting a lot of light. This is thermally generated light very much like when a piece of iron is heated and starts glowing red. This heated gas is called the accretion disk.
In this campaign, we will take measurements of the radio light and the infrared light and see whether the ratio of the non-thermal radiation (radio) to thermal radiation (IR) is related to the mass of the supermassive black hole. The Spitzer Space Telescope will image the AGN in the 3.6 to 8um range and that will be compared to data gathered by the GAVRT students in the S and X radio bands.
GAVRT has been accepted as an educational partner in the upcoming NASA mission, Juno. Juno is a Jupiter polar orbiter, which is scheduled to launch in 2011 and to arrive at Jupiter in 2016. For a year, Juno will orbit Jupiter every 11 days as it attempts to probe the interior of Jupiter. By precisely mapping the magnetic field close to the planet, Juno will help us understand the magnetic dynamo, which must lie deep inside the giant planet. Using Doppler measurements of the spacecraft's orbital velocity as it closely orbits the planet at 32 different longitudes, Juno will determine the gravitational field and learn still more about the interior structure. We will also be measuring the mass of Jupiter's solid core (if it has one) and improving our understanding of the belts and zones. Juno will use radiometers at six different microwave frequencies to penetrate deep into the Jovian atmosphere, measuring the global water/oxygen abundance, which is crucial to understanding how and where the planet formed. The microwave observations will also yield valuable information about the dynamics of Jupiter's atmosphere, helping us solve the many puzzles of Jupiter's weather and atmospheric system. Juno will fly over Jupiter's poles for the first time, taking pictures of the aurora (Northern and Southern lights) and measuring the magnetic field and particle fluxes in the radiation belts. Juno's microwave radiometers will also map the synchrotron emission from the inside, allowing vast improvements to our computer models of the radiation belts. NASA's Juno Mission is expecting GAVRT to supply the needed ground-based radio observations.
The LCROSS (Lunar CRater Observation and Sensing Satellite) Mission is designed to impact the Moon's South Pole to search for water ice beneath its permanently-shadowed craters. The search for water is very important to the possibility of future human activities on the Moon. LCROSS will make the first definitive measurements for water within a very cold crater. Using a suite of instruments, including infrared and visible spectrometers and cameras, LCROSS will be able to identify the presence of water or other constituents in the impact ejecta cloud. The plume should be visible to small optical telescopes on Earth. It is scheduled to launch on March 2nd, 2009 and be in the accurate orbital plane for impact in late 2009.