Transits of Venus, 2004:
From Venus orbit insertion to July 1980, periapsis was held between 142
and 253 km (at 17 degrees north
latitude) to facilitate radar and ionospheric measurements. The spacecraft
was in a 24 hour orbit with an apoapsis
of 66,900 km. Thereafter, the periapsis was allowed to rise (to 2290 km at
maximum) and then fall, to conserve
fuel. In 1991 the Radar Mapper was reactivated to investigate previously
inaccessible southern portions of the
planet. In May 1992 Pioneer Venus began the final phase of its mission, in
which the periapsis was held between
150 and 250 km until the fuel ran out and atmospheric entry destroyed the
spacecraft the following August.
04 May 1989 - Launch
from the MEDIA RELATIONS OFFICE, JET PROPULSION LABORATORY The Saturn-bound
Cassini spacecraft successfully performed a flyby of the planet Venus on April
26, 1998, coming about 284 kilometers (176 miles) from the Venusian surface.
The flyby gave the Cassini spacecraft a boost in speed of about 7 kilometers
per second (about 4 miles per second) help the spacecraft reach Saturn in July
2004.
"All indications are that the spacecraft did exactly what we expected," said
Deputy Program Manager Ronald Draper at NASA's Jet Propulsion Laboratory, Pasadena,
CA. One-way light-time to the spacecraft from Earth was about 7-1/2 minutes.
Leaving Venus, the spacecraft was moving at more than 141,000 kilometers per
hour (87,000 miles per hour). Science instruments on the spacecraft searched
for lightning in Venus's atmosphere during the flyby, and the radar instrument
onboard was activated to test a bounced signal off Venus's surface.
In its long trajectory to Saturn, Cassini will perform another flyby of Venus
next June, one of Earth in August 1999, and one of Jupiter in 2000. All of the
flybys impart more speed to the spacecraft to allow it to reach its final destination
of the Saturnian system. After it enters orbit around Saturn in 2004, Cassini
will study the ringed planet, its moons and ring system for at least four years.
It will also deliver a scientific probe called Huygens to parachute to the surface
of Saturn's largest moon, Titan.
On line 6 of Section 10.2, p. 174, read 225 Earth days for 105 Earth days.
http://www.users.zetnet.co.uk/pete/Venustransit.htm
http://canopus.saao.ac.za/~wpk/tov1882/tovdata_e.html
http://perso.cybercable.fr/eclipses/transit_venus.htm
http://www.phys.uu.nl/~bassa/index_miscell.htm
Venus Images
Timelines for Pioneer Venus and Magellan space probes:
Pioneer Venus
Magellan
The mission
proceeded as follows:
10 Aug 1990 - Venus orbit insertion and spacecraft checkout
15 Sep 1990 - Cycle 1: Radar mapping (left-looking)
15 May 1991 - Cycle 2: Radar mapping (right-looking)
15 Jan 1992 - Cycle 3: Radar mapping (left-looking)
14 Sep 1992 - Cycle 4: Gravity data acquisition
24 May 1993 - Aerobraking to circular orbit
03 Aug 1993 - Cycle 5: Gravity data acquisition
30 Aug 1994 - Windmill experiment
12 Oct 1994 - Loss of radio signal
13 Oct 1994 - Presumed loss of spacecraft
Cassini Flies By Venus
Number of Earth days correction
