Remote Sensing of the Ocean and Atmosphere John Wilkin jwilkin rutgers edu IMCS Building Room 214C 732 932 6555 ext 251 Orbits and Measurement Geometry Johannes Kepler 1571 1630 German mathematician astronomer and astrologer 1 Planets move in elliptical orbits with the sun as one focus 2 the radius vector from the sun to the planet sweeps out equals areas in equal times 3 T2 R3 ratio is constant for all planets where T is orbital period and R is semimajor axis of the orbit Epoch UTC 10 07 53 AM Monday January 28 2008 Eccentricity 0 0005362 Inclination 51 6418 Perigee Height 334 km Apogee Height 341 km Right Ascension of Ascending Node 22 2238 Orbit Number at Epoch 52631 Revolutions per Day 15 77540422 Nov 5 2007 view from Space Shuttle Stewart R H 1985 Methods of Satellite Oceanography University of California Press 360 pp x axis Stewart R H 1985 Methods of Satellite Oceanography University of California Press 360 pp http spaceflight nasa gov realdata elements See graphics of orbital elements and data for ISS Jason 1 launch from Vandenburg Air Force Base California Orbit http www aviso oceanobs com en missions current missions jason 1 orbit index html Launch http www youtube com watch v Z4WHOSF2Ktg Other launches Delta II Themis http www youtube com watch v p pAhPecto0 Ariane http www youtube com watch v OfONuo3h3t0 http www youtube com watch v kYUrqdUyEpI Jason 2 OSTM http www youtube com watch v cf0loVEs lo Topex Poseidon launched with Ariane rocket http sealevel jpl nasa gov gallery tiffs videos launch mov Pegasus vehicle aircraft launch http www youtube com watch v QRHiTvRHHd8 OSTM Jason 2 Boost Profile Space craft separation Hohmann Transfer Maneuver to different inclination http en wikipedia org wiki Hohmann transfer http www nytimes com 2007 02 06 science space 06orbi html emc eta1 On Jan 11 2007 China tested an antisatellite rocket The initial collision added 800 to 1000 pieces of space junk to the current total of detectable objects How many detectable objects 4 inches are in orbit Collisions between existing debris generate additional pieces of debris There is concern that eventually a chain reaction will ensue the Kessler syndrome littering the low earth orbit LEO with debris making it almost impenetrable to new satellite launches for fear of collision http www nytimes com 2007 02 06 science 20070206 ORBIT GRAPHIC html Kessler D J and Burton G Cour Palais Collision frequency of artificial satellites The creation of a debris belt Journal of Geophysical Research Vol 83 June 1978 2637 2646 http spaceflight nasa gov realdata elements See graphics of orbital elements and data for ISS Sidereal day time it takes for Earth to rotate through 360o This is slightly shorter than a solar day 24 hours There are 365 25 solar days in a year but 366 25 sidereal days Sidereal day 365 25 366 25 24 29 93 hours solar sidereal http en wikipedia org wiki Sidereal time SeaWiFS daily coverage Terra satellite MODIS instrument coverage of all instrument swaths during a single day 01 28 2006 Jason altimeter satellite ENVISAT 35 day repeat Equatorial separation of Jason groundtracks is 315 km Scan geometry zenith angle w r t satellite nadir look angle and solar zenith angle w r t local vertical Fixed solid angle Field of View FOV such as for an optical lens gives elliptical footprint off nadir and varying spatial resolution in the scan View satellite orbits and ground tracks at http science nasa gov realtime jtrack Spacecraft html Internet resources on orbits and satellites http science nasa gov realtime jtrack Spacecraft html Shows ground tracks and 3 D orbits for all satellites Notice the clusters of satellites in the major categories or orbits Geostationary Polar orbiting NOAA Topex ERS Envisat Low Earth orbit Iridium HST ISS GPS Unusual orbits especially ground track Chandra IMAGE CRRES in a geosynchronous transfer orbit http heavens above com Shows predicted orbits and visibility magnitudes and star charts of pass trajectories for all satellites See Homework 1 http tinyurl com 11 670 451 homework 1 http spaceflight nasa gov realdata elements See graphics of orbital elements and data for ISS Real time satellite tracking at http www n2yo com