A few posts ago (http://futureplanets.blogspot.com/2009/10/venus-new-frontiers-radar-mapping.html), I wrote about proposed radar missions to remap Venus at higher resolution. At that time, the idea of doing this within a New Frontiers budget (~$650M) was an eye opener for me. I listened into part of the most recent VEXAG meeting, and learned of a Discovery mission (~$425M) that could remap Venus.
The principle investigator, Dr. Sharpton, sent me the following synopsis of the mission: "RAVEN, utilizes the latest in the RADARSAT lineage, extending back to 1996 (RADARSAT 1 launched in Nov. '95). We can accomplish reconnaissance level mapping of Venus at 30-m/px and map about 25% of Venus each cycle (a venusian day). Alternatively, we could map about 3% of the planet at 3-m resolution each cycle. Obviously, we would want to have a combination of resolution modes and have overlap so that we can extract topography. Topographic resolutions would be on the order of 20m vertical resolution and either 300-m postings (if using 30-m images) or 30-m postings (with 3-m images). If InSAR turns out to be feasible (we believe it will), the vertical resolutions would drop to a meter or less."
Dr. Sharpton pointed me to an AGU abstract about the mission. Since there is no easy way to link to AGU abstracts, I'm posting parts of it below. You can search for it and other planetary abstracts athttp://agu-fm09.abstractcentral.com/planner
RAVEN – High-resolution Mapping of Venus within a Discovery Mission Budget
V. L. Sharpton1; R. R. Herrick1; F. Rogers2; S. Waterman3
1. University of Alaska Fairbanks, Fairbanks, AK, USA.
2. The Boeing Company, Huntington Beach, CA, USA.
3. Alliance Spacesystems, Boulder, CO, USA.
It has been more than 15 years since the Magellan mission mapped Venus with S-band synthetic aperture radar (SAR) images at ~100-m resolution. Advances in radar technology are such that current Earth-orbiting SAR instruments are capable of providing images at meter-scale resolution. RAVEN (RAdar at VENus) is a mission concept that utilizes the instrument developed for the RADARSAT Constellation Mission (RCM) to map Venus in an economical, highly capable, and reliable way. RCM relies on a C-band SAR that can be tuned to generate images at a wide variety of resolutions and swath widths, ranging from ScanSAR mode (broad swaths at 30-m resolution) to strip-map mode (resolutions as fine as 3 m), as well as a spotlight mode that can image patches at 1-m resolution. In particular, the high-resolution modes allow the landing sites of previous missions to be pinpointed and characterized... Our current estimates indicate that within an imaging cycle of one Venus day we can image 20-30 percent of the planet at 20–30-m resolution and several percent at 3-5 m resolution. These figures compare favorably to the coverage provided by recent imaging systems orbiting Mars. Our strategy calls for the first cycle of coverage to be devoted to imaging large geographic areas (e.g., Thetis Regio) at 20–30-m resolution with interleaved observation of pre-selected targets at high resolution. The second cycle will include additional imaging, but the focus will be repeat-pass coverage to obtain topography for a significant fraction of the first-cycle targets... All components of the spacecraft are expected to remain operational well beyond the nominal mission time, so global mapping at 10 m or better resolution during an extended mission is conceivable."
Using the technology of an Earth-orbiting satellite for exploring another planet while staying way up above the hellishness of Venus. That makes two commendable characteristics right there.ReplyDelete
Don't forget that Mars Observer "used the technology of an Earth-orbiting satellite for exploring another planet" with disastrous results, because its builders failed to adequately consider all the complications in flying that design in an environment for which it had not originally been designed. Hopefully NASA has learned the hard way from that experience to take more care -- and if it has, this does indeed look like a very promising mission concept.ReplyDelete
I confess skepticism as to whether they can do this within the Discovery cost cap, but they could certainly do it within the New Frontiers cap. But this would provide enough margin that they might also be able to augment the payload, as OSIRIS' payload has been augmented in an (as yet unspecified) way during its transformation into the NF-class "OSIRIS REx" proposal.ReplyDelete
Possibilities: (1) a dedicated and therefore higher-resolution radar altimeter; (2) a near-IR spectrometer to scan the surface for compositional data; (3) a deep-penetration radar sounder to look for stratigraphy up to several km below the Venusian surface. You may recall that the first and third instruments comprised the payload of Bruce Campbell's "VISTA" Discovery proposal.
The Radar technology is not used only for military purpose it can also be used for another different application.