EnVision Mission Outline
The core payload required to deliver the science objectives are:
- VenSAR, an S-band phased array antenna, developed from the Sentinel-1 and NovaSAR-S radar payloads
- SRS, the Subsurface Radar Sounder, inheriting experience gained with MARSIS and SHARAD
- VEM, the Venus Emissivity Mapper, building on the success of VIRTIS and VMC on Venus Express, and consisting of the VEM-M mapper and VEM-H spectrometer
Further payload to investigate complementary and more subtle atmospheric escape-related science goals may also be included, subject to spacecraft resource availability, funding, and competitive selection.
In the stowed configuration, VenSAR is folded over and off-centre, SRS is folded alongside, with solar array wings folded down on the two lateral faces and the HGA stowed on the anti-nadir face. The Solar Array is deployed immediately after launch. The HGA is then de-stowed: it can access a wide array of positions, most of the time in the anti-nadir hemisphere. In particular it has the capacity to point to Earth during boosts and during science phases at Venus. Once in the Science Orbit around Venus, SRS is deployed parallel to the launcher axis and perpendicular to the solar array to minimise diagram interferences. As the solar array is along track in science modes, SRS is across track, which is an adequate orientation. VenSAR is then deployed to overlap the central part of SRS. VenSAR must be aligned along track, which is parallel to the solar array and so the solar array yoke is long enough to prevent any conflict with VenSAR as the solar panels rotate about their two axes. As required, VenSAR is stowed over a slanting support structure that provides for a 32° angle off nadir.
The proposed mission will launch in late December 2024. Following orbit insertion and aerobraking phase, a two year nominal science operation phase will start at a 258km quasi polar circular orbit. Following any extended mission and once the orbit maintenance fuel is used up, EnVision will burn up in the Venus atmosphere.
See also the Frequently Asked Question: Is EnVision technically feasible?