VEX Science Operations and Planning, 17 - 24 March 2007
Venus Express was orbiting Venus at 189 million km from the Earth. The one-way signal travel time was 632 sec. All subsystems are operating nominally. We are currently executing the commands in MTP012, where our ascending branch is on the dark side of Venus, just about at local midnight. 30 March is our orbit 343. We are taking a lot of night-side observations in the ascending branch, as well as using the SPICAV/SOIR instrument to catch the sunrise as we come up into the Sun at the pole, which is useful for atmospheric composition studies.
Ground station support has been verified for the VIRTIS south pole movie sequence scheduled for the second week of April (DOY 98-101). Planning of science operations during this event is now finished. Initial problems communicating with DSS-63 (Madrid 70-m DSN antenna) have been overcome.
The science planning is done in two blocks: spacecraft pointing, and instrument commands. The pointing is first verified by Flight Dynamics at ESOC/Darmstadt. Output files generated by FD are used as input into the command verification done by the ESOC Venus Express Flight Control Team. MTP014, our fourteenth monthly plan, has had both pointing and commanding verified now. MTP015 has had pointing verified, and our commanding files will be verified (I hope) in the coming week.
MTP016 planning has officially begun. A new thermal envelope has been approved for use recently, and will be used for the first timein MTP016. This will allow the spacecraft to be repeatedly pointed at nadir for about 15 minutes, then pointed away to an off-track angle; repeatable over a few hours. On VEX, the instruments are body mounted, on the +Z axis, and the spacecraft must be pointed to make observations. The VEX thermal constraints do not allow lengthy pointing that exposes the -Z face to the Sun. So, if the spacecraft has the Sun behind it, and the planet in front of it, nadir observations put the Sun right up our butt. The newly approved thermal profile means that we can do such a nadir pointing, then offpoint to get the Sun off the -Z face and cool off; then repeat these observation/heating periods with cooling periods. This will allow us to make nadir observations on the ascending branch of our orbit, near local noon when the illumination is very unique, that were not possible before. The responsible engineer for MTP016, who is also our lead engineer, has put a lot of work into creating the detailed files that translate an approved concept into something that can actually be implemented. This is very detailed, time consuming work that will allow the instrument teams to get good science data, but which garners little recognition because it is buried in all the preparatory work. Given the illumination angles, this new 'pendulum' sequence will be heavily used in MTP016. We'll also have good angles to use the SPICAV/SOIR instrument to look at the Sun as it goes behind the planet as we whip over the North Pole, which provides excellent data on the atmospheric composition. These Sun occulations near pericenter, coupled with the new pendulum observations done in the ascending branch, will make up the bulk of these 28 days of observations. We'll also be doing a single orbit correction maneuver at one pericenter pass, and a unique SPICAV calibration near local noon whose thermal profile means we have to dedicate an entire orbit to just the calibration. All this planning will be proceeding over the next four weeks.
A VEX Science Working Team (SWT) meeting was held last week. A lot of good science results are getting ready to go to press in the near future, with papers in the pipelines. The meeting included an update on the VEX Education and Public Outreach, which is based at http://venus.wisc.edu/
. Some coming events they are participating in:
- ALPO Conference presentation on Venus Express June 2007
- Native Sky Stories conference at Lac du Flambeau reservation April 2007
- Presentation at EGU 2007
- Planetarium program in Brussels April 2007
Past activities have included:
- Venus E/PO workshop at Europlanets
- Teacher workshop at Belgium Institute for Research in Aeronomy, Brussels, September 2006
- Visiting Scientist International School of Brussels - September 2006
- Planetary Science 101 Teacher Workshop at DPS 2006, Pasadena, California, October 2006
A curriculum module on Venus cloud tracking is under development
The SWT included a presentation on VEX communication activities that are planned, and the instrument teams agreed to support the plans by providing inputs. These include:
End of March Web publication of recent images
11 April Web story on the orbit insertion anniversary, accompanied by new VIRTIS and VMC images
End of April Web publication of new images from VIRTIS south pole movie, assuming
Mid-May Web story on the ground-based observation campaign
Early June The Messenger Fly-By of Venus is on 05 June 2007. A few days before the Messenger fly-by,
a Web story will be published on the coordinated VEX/Messenger observing campaign
Mid June After the Messenger fly-by, VEX early science results from the Messenger fly-by will