Venus Express |
Venus Express |
Apr 12 2005, 06:56 PM
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Interplanetary Dumpster Diver Group: Admin Posts: 4404 Joined: 17-February 04 From: Powell, TN Member No.: 33 |
If all goes well, Venus Express will be a major topic for discussion in this forum a year from now. Does anyone know how good the surface coverage will be from VIRTIS and VMC? My understanding is that VIRTIS will obtain low resolution multispectral maps, and that VMC will, in addition to cloud monitoring, have one channel that can see the surface, but I don't know at what resolution or at what quality. It will be nice to have some non-radar images of Venus' surface besides the Venera snapshots and the shadowy images from Earth and Galileo's NIMS.
Ted -------------------- |
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Guest_BruceMoomaw_* |
Apr 20 2005, 10:31 AM
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Guests |
See my new note on the "Radar on Venus Express?" thread, Ted. I may be able to get you some more precise resolutional data later on if I can find the time. (However, VMC -- unlike VIRTIS -- cannot see the surface; it's entirely for UV cloud top patterns.)
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Apr 21 2005, 03:16 AM
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Interplanetary Dumpster Diver Group: Admin Posts: 4404 Joined: 17-February 04 From: Powell, TN Member No.: 33 |
Actually, VMC will have some limited capabliity to detect the surface. My source on this is the ESA mission documentation. See below:
3.7 VMC (Venus Monitoring Camera) Precursors. Imaging of the Venus disc at different wavelength was carried out by the Pioneer Venus orbiter, during the fly-bys of Mariner-10 and Galileo, and from the ground. These data was used to study the atmospheric dynamics at the cloud tops (UV), to investigate the thermospheric dynamics (UV, visible, and near-IR airglow), to map the surface brightness and to study cloud opacity variations (near-IR). However, these observations lacked global spatial and temporal coverage as well as spatial resolution. At the same time they demonstrated the power of the global imaging in the study of dynamical processes in the Venus atmosphere. VMC/Mars Express. The Video Monitoring Camera (VMC) onboard the Mars Express is a monochrome wide-angle CCD camera that was designed to take the video sequence of Beagle-2 lander leaving the Mars Express spacecraft at Mars. VMC/Venus Express. The Study Team has recommended to modify the Mars Express camera into a wide-angle multi-channel Venus Monitoring Camera. The modification will consist of adding several narrow band filters in the UV, visible, and near-IR spectral ranges that would allow the camera to provide support imaging for the whole mission, achieve additional science goals, and contribute to the public outreach programme. Preliminary study showed that the modification of VMC will not specify additional requirements to the Mars Express bus and will be fully compatible with spacecraft interfaces. More detailed elaboration of the technical, programmatic, and financial issues related to the VMC modification and accommodation on the spacecraft will be done by the VMC team, Astrium, and ESA during the pre-Phase B study in the beginning of 2002 if the mission is approved. The modified VMC will be prepared in parallel with available VMC/Mars Express in order not to jeopardize the schedule of the mission. In case of failure to modify VMC in time VIRTIS will be able to cover significant part of the VMC goals so that the achieving of the mission objectives would be secured. The VMC camera will be capable of achieving scientific goals in atmospheric dynamics and surface studies by means of global multi-channel imaging. An example of UV image expected from VMC at Venus is shown in Figure 2.2. Sequence of such images would allow one to visualize the motions of the cloud tops and to study the general circulation and wave phenomena at the altitude of ~70 km. Images of the Venus disc taken every 30 min will be used to create movies of the cloud motions and propagating waves that would be extremely valuable for investigation of the atmospheric dynamics. Figure 2.6 shows an example of image that VMC will take in the visible at night. The monitoring of airglow patterns that originate at 90-110 km is an efficient tool to study the dynamics of the Venus upper atmosphere. The VMC observations in the 1 m transparency window will give the images similar to those shown in Figures 2.5 and 2.9. These images have two types of features. Some of them belong to the surface and result from the temperature and emissivity variations. Second type of markings originates in the main cloud deck and indicates cloud opacity variations. The movies based on such imaging will be used to study global atmospheric dynamics at ~50km. To summarize, VMC will fulfill the following scientific goals: Support imaging, i.e. global imaging context for the whole mission; Observations of the global cloud motions in the UV and near-IR spectral ranges; Study of distribution of the unknown UV absorber at the cloud tops; Monitoring the UV and visible airglow and its variability as dynamical tracer; Mapping the surface brightness temperature distribution and search for volcanic activity. Besides important scientific goals the VMC imaging and movies will significantly contribute to the public outreach programme. -------------------- |
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