Chandrayaan-II, All Chandrayaan-II related articles |
Chandrayaan-II, All Chandrayaan-II related articles |
Dec 21 2010, 05:47 PM
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Junior Member Group: Members Posts: 21 Joined: 23-December 08 From: Mumbai Member No.: 4513 |
RussianSpaceWeb has reported that the possible landing sites for Chandrayaan-II called Luna-Resurs by the Russians have been selected. The selection is not final and seems to have been made (or covers only the Russian angle of the story) by Russian space organizations.
There is a detailed account of the selected landing sites for Chandrayaan-II here: http://www.russianspaceweb.com/luna_resurs_landing.html Pradeep -------------------- Pradeep Mohandas,
SEDS India. |
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Jul 23 2019, 08:22 AM
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Member Group: Members Posts: 127 Joined: 3-September 12 From: Almeria, SE Spain Member No.: 6632 |
Hi all!
Some thoughts: "Noon naps" (here in Spain: siesta) are probably not necesary, because the sun never rises more than 20deg above the horizon. This keeps the surface temperature rather low. Thermodynamic equilibrium: - Max. solar irradiation on horizontal surface: 1367W/m² x cos(70°) = 470W/m² - Thermal reradiation: 470 = 5.67e-8 x T^4 => Noon-Temperature T = 301K = 28°C (like here last night ) This is approximately, no reflection of sunlight or emittance of IR <1 was included. But in any case, not as hot as on other places. At the time of landing, the terminator is at 0deg longitude. The landing site is at 23°E, this means that at this site, the sun is already 1.5 Earth-days up. This has to be taken into account when somebody speaks about "14-Earth days operation time". It will be not more than 12.5 Earth days. If they achieve night survival, then it will be more of course. (This does not take into account possible "seasonal effects". As the Moon's axis is tilt only 1.5° vs the ecliptic, this is normally negligible, but not when coming close to a pole. 70°S is not yet close enough to be important, but I wouldn't be surprised if they could win (or loose) another half a Earth-day or so. And, of course!, terrain also matters! If there's a small hill in the west, the sunset might be significantly earlier.) If somebody wants to do detailed calculations, this great page helps: https://trek.nasa.gov/moon/index.html The solar panels of the lander and the rover are mostly vertical. As far as I can see on the photos, neither panel is steerable. The lander has one side (I suppose this will face south) with the rover and without solar panels, another two sides (I suppose facing east and west) with solar panels, and one side (I suppose facing north) that's never visible in the photos, so I don't know what's there. Hopefully another solar panel. If not, they will have a hard time around local noon. The lander has one solar panel that can be flipped to vertical, but doesn't seem to be steerable! This means that the lander should always move or at least park in a sun facing direction! Remember, over the lunar day, the sun will move in the sky from east (at the horizon) to north (elevation <20°) to west (again at the horizon). I wonder how they will manage the landing on a safe spot. The sun is very low during landing, and the shadows will be very long. A system like the one used by Cháng'é-3 and 4 (imaging, terrain recognition) will probably have a hard time to work. Shadows, yes, it will be interesting to see how they will hamper (or not?) the navigation of the rover. Somebody knows what capabilities they have to detect water? I don't expect it directly on the surface, but not too many cm below, there might be traces. Now let's cross fingers that they are successful with the flight and the landing. This place will give a first small hint about how the conditions on the real pole might be. Regards Thorsten |
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