First Earth Swing-by
Rosetta will approach from the direction away from the Sun and have its closest approach on the illuminated side of the Earth. This plot shows the swing-by in the ecliptic plane, as seen when looking from the top (north ecliptic pole) onto the plane of the Earth's orbit. As the spacecraft approaches, it will seem to fly to the west and will disappear on the dayside of the Earth. After the swingby, Rosetta is set on a course to Mars, where it will experience the second planetary swing-by on 26 February 2007.
This is the first of four planet swing-bys (three times with Earth, once with Mars) that Rosetta will carry out in its long journey to its target comet, Churyumov-Gerasimenko. Swing-bys are necessary to accelerate the spacecraft using the planet's gravity, such that the orbital velocity of the comet can be eventually achieved.
Observing the Swing-by
Rosetta approaches from an area on the sky at the border between the constellations Leo and Sextans, visible almost all night from the northern and most of the southern hemisphere.
The spacecraft should become visible in large amateur telescopes around 26 February 2005, when it reaches a brightness of 18 magnitude. On the evening of the closest approach, it will move away from the constellation Sextans after sunset and move towards the direction of the Sun, crossing the complete sky. Europe is favourably placed to follow this event.
For observation details of the swing-by follow the related link to the dedicated webpage on the right-hand side.
28 February 2005
Taken by: Thomas Hugentobler
Time: 21:38 - 21:53 UT
Location: Bolligen, Switzerland, 46° 59' 11" N, 7° 30' 7" East
Telescope: Meade SCT 12" (30cm) at F/2.7
CCD-Camera: SBIG ST-7 4 exposures of 180 seconds
Field of the image: 22 x 17 arc minutes, north is up (inclined 17° to the right)
Image Centre:RA (2000) 11h 06m 48s, DEC +2° 15' 31"
Spacecraft and Payload activities
A number of activities are planned during the swing-by. A few hours before the closest approach the spacecraft will be pointed to the Moon. The remote sensing instruments and some other instruments are switched on for calibration purposes. After the swing-by, one of the two Navigation Cameras will be switched to the so-called asteroid tracking mode, where - rather than an asteroid - the Moon will be tracked by the camera.
Rosetta is scheduled to fly by two asteroids (Steins in September 2008 and Lutetia in July 2010), where the tracking mode will be used to keep the spacecraft instruments centered on the asteroid. The tracking on the Moon around this Earth swing-by will act as a test of this mode.