Cassini Scores Closeup Flybys
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Inside October 7, 2005 Volume 35 Number 20 News Briefs . 2 New Caltech Antenna Installed . 3 Special Events Calendar . 2 Spitzer, Hubble Team Up . 3 Process Improvement Noted . 2 Letters, Retirees, Classifieds . 4 Jet Propulsion Laboratory CASSINI PERFORMED BACK-TO-BACK FLYBYS A false-color image of Hyperion reveals crisp details and variations in of Saturn’s moons Tethys and Hyperion on the final weekend of Sep- color across the strange surface that might represent differences in the tember, coming closer than ever before to each of them. composition of materials. Hyperion has a notably reddish tint when Tethys has a scarred, ancient surface, while Hyperion is a strange, viewed in natural color. spongy-looking body with dark-floored craters that speckle its surface. Scientists are extremely curious to learn what the dark material is New images, mosaics and a movie of these bodies are available at that fills many craters on this moon. Features within the dark terrain, Cassini http://saturn.jpl.nasa.gov, www.nasa.gov/cassini and http://ciclops.org. including a 200-meter-wide (650-foot) impact crater surrounded by rays Images of Tethys taken during Cassini’s close approach to the moon and numerous bright-rimmed craters, indicate that the dark material on Sept. 24 reveal an icy land of steep cliffs and craters. Cassini pho- may be only tens of meters thick with brighter material beneath. scores tographed the moon’s south pole, a region not seen by JPL’s Voyager Scientists will also be examining Cassini’s sharp views in hopes of spacecraft. determining whether there have been multiple episodes of landslides on A giant rift called Ithaca Chasma cuts across the disk of Tethys. Much Hyperion. Such “downslope” movement is evident in the filling of craters closeup of the topography in this region, including that of Ithaca Chasma, has with debris and the near elimination of many craters along the steeper been thoroughly hammered by impacts. This appearance suggests that slopes. Answers to these questions may help solve the mystery of why the event that created Ithaca Chasma happened very long ago. this object has evolved different surface forms from other moons of flybys Near a prominent peaked crater named Telemachus are the remnants Saturn. of a very old crater named Teiresias. The ancient impact site is badly Cassini flew by Hyperion at a distance of only 500 kilometers (310 overprinted and eroded by impact weathering and degradation. All that miles). Hyperion is 266 kilometers (165 miles) across, has an irregular By Carolina Martinez remains is a circular pattern of hummocks that mark where the old shape and spins in a chaotic rotation. Much of its interior is empty crater rim existed. Many of the fresh-appearing craters exhibit unusual- space, explaining why scientists call Hyperion a rubble-pile moon. This ly bright crater floors, in contrast to the dark-floored craters seen on flyby was Cassini’s only close encounter with Hyperion in the prime Saturn’s oddly tumbling moon Hyperion. mission’s four-year tour. Over the next few months, scientists will study Images of Hyperion taken on Sept. 26 show a surface dotted with craters the data in more detail. and modified by some process, not yet understood, to create a strange, Cassini flew by Tethys at a distance of approximately 1,500 kilometers “spongy” appearance, unlike the surface of any other Saturn moon. (930 miles) above the surface. Tethys is 1,071 kilometers (665 miles) across and will be visited again by Cassini in the summer of 2007. At left is the closest Cassini image of Tethys’ icy surface taken during the Sept. 24 flyby. At right is Hyperion as imaged during the Sept. 26 flyby. ARE WE ALONE IN THE UNIVERSE? ARE THERE This setup may eventually help scientists select targets for NASA’s PLANETS LIKE EARTH AROUND OTHER “SUNS” envisioned Terrestrial Planet Finder missions. The success of those potential future missions, one observing in visible light and one in that might harbor life? Thanks to a recent technology breakthrough NASA takes infrared, depends on being able to find Earth-like planets in the dust on a key NASA planet-finding project, the dream of answering those rings around stars. questions is no longer light-years away. “We have proven that the Keck Interferometer can block light from giant step to On a crystal clear, star-filled night at Hawaii’s Keck Observatory on nearby stars, which will allow us to survey the amount of dust around Mauna Kea, NASA engineers successfully suppressed the blinding light them,” said Dr. James Fanson, project manager for the Keck Interfer- finding Earth- of three stars, including the well-known Vega, by 100 times. This break- ometer at JPL. That survey will begin in late 2006 after the team re- through will enable scientists to detect the dim dust disks around stars, fines the nuller’s sensitivity level. like planets where planets might be forming. Normally the disks are obscured by the Combined information from all of NASA’s planet-hunting missions will glare of the starlight. provide a complete picture of possible Earth-like planets: how big they Engineers accomplished this challenging feat with the Keck Interfer- By Jane Platt are, whether they are warm enough for life, and if their atmospheres ometer, which links the observatory’s two 10-meter (33-foot) tele- and surfaces show chemical signatures of current life. scopes. By combining light from the telescopes, the Keck Interferometer “People have been talking about whether there are other Earths out has a resolving power equivalent to a football-field sized telescope. The there for 2,500 years. Only now are we developing the technology to go “technological touchdown” of blocking starlight was achieved by adding find out,” said Michael Devirian, manager of NASA’s Navigator Program an instrument called a “nuller.” at JPL, which is investigating potential planet-exploring missions. The W.M. Keck So far, scientists around the world have found 150 planets orbiting Observatory in other stars. Most are giants, like Jupiter; none is as small as Earth. Scientists Hawaii. believe the best odds of finding life outside our solar system are on Earth-sized planets, particularly those with the right temperature, density and chemistry. More information on NASA’s planet-finding missions, including the Keck Interferometer and Terrestrial Planet Finder, is at http:// planetquest.jpl.nasa.gov. JPL manages the Keck Interferometer and Terrestrial Planet Finder missions for NASA’s Science Mission Directorate, New policy on NASA logo Caltech to implement parking fees 2 NASA Headquarters recently re- Caltech has announced that a new Universe leased updated instructions on the use paid parking program will go into effect Special Events Calendar of the NASA logo and taglines. The in October for all campus parking. memo, from Chief of Strategic Commu- Caltech faculty, staff and visitors will nications Joe Davis, states that all be required to purchase parking per- Ongoing Support Groups Saturday, October 15 NASA mission directorates, mission mits of varying lengths. The new regu- Alcoholics Anonymous—Meets Wednes- Folk and Jazz Music—The 3 Jammin’ support offices and centers should use lations will be enforced from 8 a.m. to days at 11:30 a.m. Gents will perform at 8 p.m. in Cal- the agency insignia—or “meatball”—as 5 p.m. Monday through Friday, begin- tech’s Beckman Auditorium. Tickets are the sole logo on all official communica- ning Oct. 24. Caregivers Support Group—Meets the $29, $25 and $21; $10 for high school tion materials. In addition, the memo Visitors will be required to purchase first Thursday of the month at noon in age and younger. For more informa- called for discontinuing use of slogans parking permits at automated kiosk Building 167-111 (the Wellness Place). tion, call (626) 395-4652 or visit and tag lines such as the “Explore. “pay stations” located in the parking www.events.caltech.edu. Codependents Anonymous—Meets at News Discover. Understand” line that NASA structures on North Wilson Avenue, noon every Wednesday. used earlier this year. Holliston Avenue and California Boule- Sunday, October 16 “The memo formalizes what has vard, as well as parking lot 6, behind Lambda (Gay, Lesbian, Bisexual and been our policy for some time,” said the tennis courts on California Boule- Transgender Networking Group)— Caltech/JPL Flying Club—The annual Briefs FRANK O’DONNELL, manager of JPL’s vard, west of Hill Street, and parking Meets the first Friday and third Thurs- fall picnic will be held at El Monte Institutional Communications Office. lot 12, at the corner of Wilson Avenue day of the month at noon in Building Airport from 11 a.m. to 5 p.m. See “We use the NASA insignia as the main and Del Mar Boulevard. 111-117. For more information, call http://aacit.caltech.edu for details and directions, and RSVP for free 15- visual identifier on materials for the Permits will range from $1 per hour Randy Herrera, ext. 3-0664. minute introductory flying tours (for public, but have ‘Jet Propulsion Labo- to a maximum of $5 per day. Parents Group for Children With Spe- CIT/JPL community) to Stuart ratory’ and ‘California Institute of A free shuttle service between JPL cial Needs—Meets the second Thurs- Stephens, ext. 3-7807. Technology’ spelled out where appro- and Caltech is available for staff. The day of the month at noon in Building priate. At the same time, as JPLers we shuttle runs Monday through Friday, 167-111 (the Wellness Place). Chamber Music—The Janaki Trio will are not NASA employees, so it would departing approximately every 20 give a free concert at 3:30 p.m.