VeRa – Venus Express Radio Science
The direct radio contact between spacecraft and the ground station on Earth is used for the radio sounding of neutral and ionised media.
The scientific goals of the Venus Radio Science Experiment (VeRa) are:
(1) Radio sounding of the Venus ionosphere,
from ~ 80 km altitude to the ionopause at 300 km to 600 km altitude depending on planetary latitude zenith angle, local time, and solar activity to:
- deduce vertical profiles of the electron density,
- determine the height of the ionopause,
- study the interaction of the solar wind with the Venus ionosphere as a function of local time.
2) Radio sounding of the neutral atmosphere from 35 – 40 km up to 100 km altitude to deduce vertical profiles of the neutral number density, the temperature and the pressure in dependence of the planetary latitude and local time.
(4) Studies of the coronal large scale structures, the solar wind turbulence and coronal mass ejections (CME) during the conjunction of Venus around the Sun. For terrestrial planets one distinguishes between superior and inferior conjunctions, i.e. the planet resides on a line: planet-Sun-Earth (superior conjunction) or Sun-planet-Earth (inferior conjunction).
VeRa uses the radio carrier signals of the spacecraft at the X-band (8.4 GHz) and az S-band (2.3 GHz) which are transmitted simultaneously by the high gain antenna (HGA).