kelly l. perry nasa jet propulsion laboratory university of southern california...
TRANSCRIPT
MISSION PHASES LAUNCH CRUISE TOUR
SPACECRAFT POWER
INSTRUMENTATION
SCIENCE
• Cassini is 22 ft tall and 13 ft wide
• Weighs more than 10,000 pounds
• 12 Science Instruments
• Scientists and engineers from 17 different countries worked together to build Cassini• Launched in 1997 and began to orbit Saturn in July 2004
• 2 million mile journey
• Spacecraft travels at speeds between 2-12 miles per second
• Around the Rose Bowl Loop in 1-4 times per second
• Energy for launch was obtained by combustion of chemical propellants
• Used Titan IVB/Centaur • 2.2 million pounds at launch• 2 solid-propellant stage-zero motors, a liquid propellant 2-stage core and a 16.7ft diameter payload fairing
• Cassini required upgraded solid rocket boosters and a Centaur high-energy stage
• Launched from Cape Canaveral on Oct 15, 1997
If Cassini were launched from the equator, would it have required more or less energy?
• Rocket was most powerful available, but it wasn’t good enough
• GRAVITY ASSISTS were needed• Used since the 1970s• Increases Cassini’s sun-relative speed by using gravity during fly-bys
• Require 3 bodies: spacecraft, assisting body and central body• Example: Cassini, Venus and the sun
• Propellant used to change trajectory
• Gravity Assists Continue: Cassini, Titan, Saturn
• Titan is Saturn’s largest moon.• Larger than Mercury• Has an atmosphere (Nitrogen) that resembles Earth several billion years ago
Do Gravity Assists violate the Law of the Conservation of
Energy?What is the cost of the
energy gained?
• Cassini obtains its power from 3 Radioisotope Thermoelectric Generators (RTGs)
• NOT NUCLEAR REACTORS• DO NOT USE FISSION OR FUSION• Provide power through the natural radioactive decay of plutonium
• Pu-238 (non-weapons grade isotope)• Heat generated by decay is converted to electricity
Power is a negotiated resource on the spacecraft!!!
• Optical Remote Sensing• Composite Infrared Spectrometer (CIRS)• Imaging Science Subsystem (ISS)• Ultraviolet Imaging Spectrograph (UVIS)• Visible and Infrared Mapping Spectrometer (VIMS)
• Fields, Particles and Waves• Cassini Plasma Spectrometer (CAPS)• Cosmic Dust Analyzer (CDA)• Ion and Neutral Mass Spectrometer (INMS)• Magnetometer (MAG)• Magnetospheric Imagining Instrument (MIMI)• Radio and Plasma Wave Science (RPWS)
• Microwave Remote Sensing• RADAR• Radio Science (RSS)
Side-by-Side comparison of largest lake found on Titan (22 Feb 2007) and Lake Superior
RADAR confirmed existence of large lakes & rivers
(images from saturn.jpl.nasa.gov)
• Main rings would span from the Earth to the Moon• The rings are only half of a mile thick
• Composed of Ice, Rocks and Dirt• Particles the size of dust to mountains
• The Rings are still growing• The E-Ring is fed by eruptions from Enceladus
• Shepherding satellite, constraining the inner edge of the F-Ring
• Irregular shape: 12.4 mi in diameter
• Probably a porous ice body
27 November 2005: Jets of Icy Particles burst from Enceladus
• Green Flagellates: 440 and 665 nm• Diatoms: 440, 500-540 nm
• Dinoflagellates: 440, 500-540 nm• Cyanobacteria: 440, 495, 600-640 nm
Marine Mammal Care Center in San Pedrowww.marinemammalcare.org
DOMOIC ACID Poisoning• aka Amnesiac Shellfish Poisoning• Toxin released by Pseudo-nitzschia
(Photos provided by Robin Riggs, 2005)
HARMFUL ALGAL BLOOM (HAB) occurs when toxic algae grow too quickly• Not all algae or algal blooms are toxic!
Pseudo-nitzschia blooms are trickier!• They’re invisible!
Non-Toxic Red Tide in New Zealand(image from www.whoi.edu/redtide/)
• During El Nino events, sea level and SST in California are higher than normal.• Thermocline deepens• Northward flow brings low nutrient waters• Lower Phytoplankton due to less nutrients
• Time for RADAR!!!
