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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.

Payload Configuration

Figure 1: Schematic illustration of EnVision's core instruments, click for details

Mission profile

Following an end 2024 launch, five month interplanetary cruise, and Venus capture, EnVision will undertake 4–6 months aerobraking to achieve a 258 km circular polar (88° inclination) orbit. For illustrative purposes, EnVision will start its 4 Cycle, 2 year 8 month, nominal mission in February 2026, which will focus on interferometry, stereoSAR and locating the Venera landers. Given sufficient remaining resources, a 20 month extended mission will follow during which EnVision will continue interferometry, complete global stereo coverage and acquire significant areas of polarimetric and high resolution data. This extended mission phase will likely end in May 2030, having taken full advantage of inferior conjunction, but could be continued until resource depletion.

Figure 2 :   Data return strategy

VenSAR will meet the science requirements for improved topography, change detection, and discrimination of surface materials by using different modes: stereo imaging, interferometry, and polarimetry. In addition, VenSAR will locate and provide context imagery for the Venera lander sites through a combination of high resolution mapping and sliding spotlight modes. These different data sets are acquired in swaths sufficiently large to allow their collection sequentially across sets of four orbits (figure below).

Figure 3 :   Imaging strategy

Interferometric data are collected during every set, as a pass-to-pass pair during the first cycle, and as opposite-look pairs (not shown above) in subsequent orbits. Subject to data rate limitations, VenSAR will acquire stereo pairs and either polarimetric or high resolution swaths. The subsurface sounder will continuously record data along the nadir track while VEM will operate across the night side of Venus only. A four orbit mapping set (A) starts with the acquisition of a dual 40 km stereo pair swath (1) using scanSAR; on the next orbit Venus has rotated 10 km, and VenSAR acquires the first of two (2, 3) interferometric stripmap swaths 43 km wide that will form a pass-to-pass interferometric topographic baseline swath 40 km wide; in the fourth orbit of the set either 40 km wide polarimetric (HH, VV, HV) scanSAR or 40 km wide high resolution stripmap swaths may be acquired (A4 and C4). All swaths can combine with the next adjacent set (B) to provide continuous coverage of the Venus surface. At orbit D the near stereo swath combines with the far stereo swath (1) to produce a stereo pair with at least 20° angular separation. Data rates permitting, SRS continuously records the nadir track. VEM operates every orbit on the night side of Venus, recording spectra, mapping emissivity and monitoring volcanic activity.

 

See also the Frequently Asked Question: Is EnVision technically feasible?