A little more information about what Venus Express will be up to around the time of, and during, the Venus Transit on 05/06 June.
Venus Express will be making a sequence of observations around the time of the transit:
- The VMC camera will obtain sequences of images of Venus in UV, visible and IR during the time of the transit, from South to North latitudes.
- The VIRTIS imaging spectrometer (an imaging spectrometer that observes in the near-ultraviolet, visible, and infrared) team will obtain data in the visible channel from the South pole and southern latitudes.
- A full Sun disk Scan will be performed by the Spicav spectrometer (an imaging spectrometer that used for analyzing radiation in the infrared and ultraviolet wavelengths), just before the transit starts.
- there will be a solar occultation observation during the time of the transit, measured by the SOIR (Solar Occultation at Infrared) instrument team that will be used to observe the Sun through Venus's atmosphere in the infrared. This measurement is described here
and more generally here
. The SOIR team has a lot of information online and has a useful twitter feed at @BIRA_IASB . There will be 4-5 people from the SOIR team in Svalbard, observing the transit from one place in Europe (above the Arctic Circle) where it will be fully visible.
The Venus transit will be a special moment for the SOIR team and their colleagues in the scientific community. The SOIR commands that will be sent to the instrument will enable recording the spectra of CO2 on the whole Venus altitude range available to the SOIR instrument. These measurements will give us indirect information about the temperature. Absorption due to aerosols will also be investigated.
Thanks to collaborations with ground-based observers, simultaneous measurements have been planned, namely with Pr. T. Widemann (Observatoire de Paris, France) and Dr. B. Sandor (Space Science Institute, Boulder, Colorado, USA). Dr. B. Sandor will, for instance, observe the Venus transit from Mauna Kea, Hawaï, using the James Clerk Maxwell (JCMT) telescope.
The data obtained with SOIR and the telescopes will be compared. This will enable scientists studying the atmospheres of exoplanets outside our solar system to test their instruments against a known, real-world example.
Note that all data from VEX observations will not be downloaded to Earth until at least 48 hours after the transit, because there is no communication with the spacecraft when it is directly in front of the Sun.