I have a large print of this webcomic on my office wall: http://xkcd.com/695/
Poor little guy. Dave _____ From: sundial [mailto:[email protected]] On Behalf Of Woody Sullivan Sent: Saturday, August 11, 2012 12:23 AM To: [email protected] Subject: Re: Sundial on Mars Colleagues: Attached is the first image of the latest "MarsDial", which indeed is the calibration device for the main camera ("Mastcam") on Curiosity Rover, which landed safely in Gale Crater on Mars 5 days ago (hurrah!). The MarsDials were originally fabricated (in 1999) for the Mars Rovers Spirit and Opportunity, which landed in 2004, and the latter of which is STILL working over 8 years later. To date over 35,000 images have been taken of the two MarsDials - the most photographed thing on Mars! As mentioned below, I was intimately involved in all aspects of making these calibration devices into working sundials - design, fabrication, operations, etc. However, because of other commitments I chose not to be part of any Curiosity efforts, so my report in the following paragraph is that of a (very) interested observer. In order to save some money, the Curiosity MarsDial is a slight modification of one of the 6 copies that we made in 1999. A couple of magnets were added (to try to repel dust), new plates were put on it to change various wording such as the date and, in particular, the motto. The motto is now "To Mars to Explore" rather than the previous "Two Worlds One Sun". But the biggest difference is that, as far as I know, no one is ever going to superimpose the hour/date lines so that it can actually be used as a sundial! And yet NASA's publicity continues to call it a sundial.....But I'm still very happy to see the first images of it (attached). A complete battery of MarsDial images taken through many filters can be found at http://mars.jpl.nasa.gov/msl/multimedia/raw/?s=3 . Cheers, Woody Sullivan ++++++++++++ This is the Mars dial designed by Woody Sullivan at the University of Washington. He gave a short update on the design at the NASS Conference in Seattle last year. Seehttp://www.sundials.org/attachments/article/174/2011%20NASS%20Conference% 20Seattle.pdf for a retrospective on the conference but very little on the dial. Yes, the sundial is based on a colour comparator and the orientation of the dial changes when the rover moves. The hour lines lines are added by NASA back on Earth. The original design is described on Woody's website, more specifically in the following article. See http://www.astro.washington.edu/users/woody/MarsDial.Plan_Rept.Jan04.pdf . Regards, Roger Bailey +++++++++++ Color calibration was the primary function, however these sundials - which are also on the previous Mars rovers - were in fact designed to also be used to show time and season. Originally they were meant to be placed on stationary landers. Since rovers can change direction and latitude, making permanent lines a problem, the solution was to superimpose time indicator lines on the images digitally so the dial can be read, as in this photo from the Spirit rover: http://www.nasaimages.org/luna/servlet/s/fb8nc5 Here is an article (in PDF) from 2003 describing the design and operation of the Mars sundials: http://www.astro.washington.edu/users/woody/MarsDial.Plan_Rept.Jan04.pdf Don Rogerson David, On http://wtvr.com/2012/08/03/nasa-mars-rover-curiosity-will-land-early-monday/ you can read that de 'sundial' is not used to have information "to calculate time of day, date, and seasons" but as an appliance to color balance the photgraphies Curiosity made. Willy Leenders Hasselt in Flanders (Belgium) Visit my website about the sundials in the province of Limburg (Flanders) with a section 'worth knowing about sundials' (mostly in Dutch): http://www.wijzerweb.be <http://www.wijzerweb.be/> +++++++++++++++++++++++ Op 10-aug-2012, om 11:03 heeft [email protected] het volgende geschreven: Dear Diallists, I thought you might find this particularly interesting, sent to me by my USA-based son. http://mars.jpl.nasa.gov/msl/multimedia/interactives/learncuriosity/index-2. html then click on the arrow until you get to the description of the 'Back' Click on the sundial (near the top/middle) Also: http://www.pcworld.com/article/260579/mars_rover_curiosity_a_complete_guide_ to_tagging_along_online.html In particular: https://twitter.com/marscuriosity https://twitter.com/sarcasticrover (unofficial I'm guessing :) David Brown Somerton, Somerset, UK *********************************************************** Prof. Woodruff T. Sullivan, III tel 206-543-7773 fax 206-685-0403 Dept. of Astronomy & Astrobiology Program Box 351580 University of Washington Seattle, WA 98195 USA
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