Envisat

Envisat was launched on 1st March 2002 by an Ariane 5 rocket from Kourou in French Guiana. The main box section measures 26x10x5m and the satellite weighs 8211kg. It is in a polar orbit which means there are regular high altitude passes from anywhere in the world making it ideal for tracking. The orbit is 783x785km which is considerably higher than the ISS or Mir. Despite this greater range it becomes the third object that I have resolved to show detail, after Mir and the ISS.

	Envisat September 2004 This image shows a good match with a VRML simulation to the right.I rotated the panels until they matched the image. A quick check shows the chosen panel angle does point at the Sun. The image has been enlarged hence no scaling can be done. Clearly the SAR antenna is not resolved.
	Envisat April 2005 The image has been enlarged x2. It is a stack of about 30 images assembled in Registax. Right clearly SAR is not resolved since it is in shadow
	Left. An animation from April 2003 shows the changing orientation of the spacecraft as it passes over. The maximum altitude of this pass from Manchester was 65°

"In flight, the major spacecraft longitudinal axis (the Xs-axis) is normal to the orbit plane, the Ys-axis is closely aligned to the velocity vector and the Zs-axis is Earth pointing. This configuration concept provides a large, modular, Earth-facing mounting surface for payload instruments and an anti-sun face for radiative coolers, free of occultation by satellite subsystem equipment."

The following image from ESA (see where is Envisat now) illustrates the point. The orbital place is through the white orbit line and into the screen. The X-axis is horizontal and hence normal to the orbital plane. The Y-axis is along the orbit and the Z-axis is perpendicular to the screen. In this case the SAR antenna always faces the Earth.

In my images North is always up, hence if the SAR antenna was resolved it would appear vertical for near overhead passes.