[Prev][Next][Index][Thread]
(meteorobs) OT: Observable CONTOUR maneuvers July 27&31, Aug03
Greetings all,
Saw this on our RASC list and am cross-posting for observers in the
mentioned areas... Off topic, but interesting. They are after
observations!
- Cathy Hall
Metcalfe, Ontario, Canada
> > Forwarded message from David Dunham
> > NOTICE: Material quoted or re-posted from the Minor Planet Mailing List
> should be proceeded
> > by the following attribution:
> > FROM THE MINOR PLANET MAILING LIST [date]. For the full text or to
> subscribe, please visit:
> > MPML Home page: http://www.bitnik.com/mp
> > MPML FAQ: http://www.bitnik.com/mp/MPML-FAQ.html
> > MPML's Yahoogroups page: http://www.yahoogroups.com/group/mpml
> > -------- 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.jhuapldot 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
> >
> > ***---------------------------------------------------------------
> >
> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > MPML is supported in part via the 2002 Shoemaker NEO Grant Program of
The Planetary Society (http://www.planetary.org)
The archive and Web site for our list is at http://www.meteorobs.org
To stop getting all email from the 'meteorobs' lists, use our Webform:
http://www.meteorobs.org/subscribe.html