Did ASTEX carry a SAR?

Ted Molczan (molczan@fox.nstn.ca)
Sun, 29 Sep 1996 20:32:42 -0400

ASTEX, (USAF) Advanced Space Technology EXperiments, (71089A / 5560)
was launched on 17 October 1971, from VAFB, into a 773 x 803 km, 
92.7 deg orbit. Its current orbit is:

ASTEX            9.6  1.5  0.0  5.8 d
1 05560U 71089  A 96270.06638362  .00000028  00000-0  84990-5 0  5316
2 05560  92.7132 293.7923 0016745 168.9527 191.2036 14.41884390307765

The RAE Table of Earth Satellites states that it has a cylindrical main 
body, 9.6 m long and 1.5 m in diameter; and 2 wings, with a span of
9.8 m. It's mass is said to be 1500 kg.

There is an illustration on pg. 106 of Giovanni Caprara's book, The 
Complete Encyclopedia of Space Satellites. The satellite's main body
consists of a cylinder, with a rocket motor and four small 'whip' 
antennas on one end, and instruments on the opposite end. Near the 
rocket motor end, there is a single panel, reminiscent of a solar panel. 
Near the instrumented end, there is a much larger panel, reminiscent of 
an SAR antenna. Which brings me to my question. Did this satellite in 
fact carry an SAR?

Judging by Caprara's illustration, ASTEX looks far more like various
SAR satellites, such as Seasat, JERS, ERS, Almaz and Radarsat, than 
any other class of satellites. The main distinguishing feature is that
most SAR satellites carry a large antenna panel, in addition to the
usual solar panel.

ASTEX has several things in common with Seasat 1, the U.S. SAR, launched 
in 1978: both incorporate an Agena D in the main satellite bus, and
both were launched into orbits of almost identical altitude. Seasat's
orbit was far more retrograde, with an 108 deg inclination, but both 
satellites had a groundtrack that nearly repeated every 43 revolutions.

I believe that the U.S. would had to have obtained some practical
experience with SAR technology before embarking on the powerful
Lacrosse satellites. Was ASTEX part of that experiential base?

Ted Molczan