This message was sent from David Dunham of Occultation fame to the the Minor Planet mailing list. To add to David's remarks CONTOUR is on the JPL HORIZONS ephemeris calculator, and can be used to generate predictions. OIG also has TLEs for this object ( 27457 ) With list members interested in observing rocket firings, They may want to take a look. You will probably need better optical aid than 7x50 binocs though. CONTOUR 1 27457U 02034A 02199.75000000 +.00000000 +00000-0 +00000-0 0 00134 2 27457 030.1915 192.4247 8916057 337.7130 001.6441 00.58031961000004 Tony Beresford -------- Original Message -------- Subject: Observable CONTOUR maneuvers, July 27&31, &Aug03 Date: Fri, 26 Jul 2002 02:18:37 -0400 On July 27, July 31, and August 3, the CONTOUR spacecraft will perform delta-V maneuvers at high altitude that might be observed from large areas of the dark side of the Earth. CONTOUR was launched on July 3rd into a 1.75-day-period Earth orbit that extends about 18 Earth radii, or almost a third of the way to the Moon, at apogee. On August 15, at 8:46 U.T., a solid rocket motor (SRM) in the center of CONTOUR will blast the spacecraft out of Earth orbit into a high-energy heliocentric trajectory that will make a distant Earth flyby a year later, then go on to encounter Comet Encke in November 2003. More Earth swingbys and comet encounters will occur after that. But for now, there are three good opportunities to observe the spacecraft while it is relatively close to the Earth. The SRM burn would be quite spectacular, but it will be performed at perigee in daylight over the Indian Ocean, too far from the nearest island to be seen. Previous CONTOUR delta-V maneuvers, called Orbit Correction Maneuvers (OCM's), have been performed at perigee in daylight, so they, too, were not observable. In summary, the three upcoming maneuvers are as follows: OCM6, a 58.5-second burn on July 27 centered at UTC 12h 02m 28.9s, 45,445 km over long. 162.42 deg. W., lat. 23.77 deg. N., visible from much of the Pacific Ocean, especially Hawaii, and also from Japan and other countries of the western Pacific, including Australia and New Zealand. OCM7, a 63.2-second burn on July 31 centered at UTC 17h 13m 09.9s, 108505 km over long. 146.91 deg. E., lat. 9.64 deg. N., visible from Japan, New Zealand, Australia, and most of Asia. OCM8, a 17.8-second burn on August 3 centered at UTC 07h 15m 55.4s, 12021 km over long. 138.49 deg. W., lat. 30.53 deg. N., visible from Hawaii and most of North America, especially the western part. I don't know how bright these burns will appear; I hope that some observations of the July 27th maneuver can be made, especially video observations with sensitive cameras like the Watec 902H or Supercircuits PC164C. I think the CONTOUR spacecraft itself, which is always in sunlight, will be only 10th to 12th mag.; it is cylindrical, about 1.7 meters high and across, covered mainly with solar cells. But it doesn't have large panels pointed towards the Earth like NEAR. The burns, with two 5-pound hydrazine thrusters, should be a few magnitudes brighter, but just how many, I don't know; maybe someone else with experience observing spacecraft maneuvers can give a good estimate. I will be interested in any observations, especially video, that might be made of these maneuvers. In addition to the delta-V maneuvers, there are smaller attitude maneuvers, called ACM's, performed in pulse mode with pairs of 0.2- pound thrusters that will be a few magnitudes fainter than the OCM's. Two ACM's are planned on July 29 starting at 10h 00m U.T.; they last typically an hour; I'll provide more information about them in my next message. Earth-centered J2000 equatorial coordinates, and orbital elements, of CONTOUR at the central time of the OCM's are given below for calculating local predictions (R.A. and Dec., and altitude and azimuth). I will try to generate some local predictions for OCM6 later today, and post them on my Web site at http://iota.jhuapl.edu I think local (topocentric) predictions can also be computed at the JPL Horizons ephemeris Web site; if they don't have CONTOUR in their data now, I'll ask to see if it can be added later today. Note that the data below for OCM6 should be quite accurate, but the times and locations of the later maneuvers will change a little due to maneuver execution errors and the slightly variable effects of atmospheric drag at the perigees. Closer to the times of the later maneuvers, better predictions will be possible. David Dunham, IOTA and CONTOUR Mission Design Team ***--------------------------------------------------------------- Name: OCM6 d-omega dV 148 (performed at true anomaly 148.5 deg., it primarily targets the desired argument of perigee for the Aug. 15th SRM burn). UTC Gregorian Date: 27 Jul 2002 12:02:28.8681 UTC (center) State Vector in Coordinate System: Earth Centered Mean J2000 Parameter Set Type: Cartesian X: 37963.979593083197 km Vx: 2.8493191365850223 km/sec Y: -28435.991238763087 km Vy: -0.5374509666709674 km/sec Z: 20865.402121262068 km Vz: 0.6408573138008424 km/sec Parameter Set Type: Keplerian orbital elements sma: 60705.896102872473 km RAAN: 191.285999418392 deg ecc: 0.891697629886 w: 339.2040580312204 deg inc: 30.575511654913 deg TA: 148.4622322180457 deg Parameter Set Type: Spherical Right Asc: 323.1658509431595 deg Decl: 23.74440950155947 deg |R|: 51819.2469065019830000 km ***--------------------------------------------------------------- Name: OCM7 d-inc. & per. lower (performed near apogee, it primarily targets the desired inclination and perigee height for the Aug. 15th SRM burn). UTC Gregorian Date: 31 Jul 2002 17:13:09.9323 UTC (center) Parameter Set Type: Cartesian X: 112710.401947623670 km Vx: 0.0171005619124146 km/sec Y: -11198.368256937616 km Vy: 0.5372407489732711 km/sec Z: 19208.226547974984 km Vz: -0.3090896893056189 km/sec Parameter Set Type: Keplerian sma: 60834.74169497374500 km RAAN: 190.8895025415419 deg ecc: 0.89078192258006 w: 339.9109821717473 deg inc: 30.74739392798233 deg TA: 180.9999998190316 deg Parameter Set Type: Spherical Right Asc: 354.3259858489416 deg Decl: 9.624994428804927 deg |R|: 114882.5231527024200000 km ***--------------------------------------------------------------- Name: OCM8 d-bigomega dV (performed at true anomaly 111 deg., it primarily targets the desired right ascension of the ascending node (RAAN) for the Aug. 15th SMR burn). UTC Gregorian Date: 3 Aug 2002 07:15:55.3766 UTC (center) State Vector in Coordinate System: Earth Centered Mean J2000 Parameter Set Type: Cartesian X: 3342.1306032929920 km Vx: 4.6119034678273367 km/sec Y: -15496.8063750805030 km Vy: -3.1684260664246771 km/sec Z: 9327.7251006836759 km Vz: 2.3403850779209407 km/sec Parameter Set Type: Keplerian sma: 60808.12340468973700 km RAAN: 190.8002487426286 deg ecc: 0.891130110024153 w: 340.1808183792037 deg inc: 30.47907158998058 deg TA: 111.0000000021569 deg Parameter Set Type: Spherical Right Asc: 282.1703353369059 deg Decl: 30.47191068517976 deg |R|: 18393.6755530298430000 km ***--------------------------------------------------------------- ----------------------------------------------------------------- Unsubscribe from SeeSat-L by sending a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org http://www.satellite.eu.org/seesat/seesatindex.html
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