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Space Log: Messenger arrives at Mercury

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george.leopold
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re: Space Log: Messenger arrives at Mercury
george.leopold   3/28/2011 9:56:28 PM
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This just in: NASA said Monday (March 28) it will release the first orbital images of Mercury from its Messenger probe this week. Among the images to be released Tuesday will be those showing "previously unseen terrain," NASA said. The images will be posted around 2 p.m. eastern here: http://www.nasa.gov/mission_pages/messenger/main/index.html

DrQuine
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re: Space Log: Messenger arrives at Mercury
DrQuine   3/26/2011 2:42:29 PM
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I'll defer to a rocket scientist for the technical details but the concept of "temperature" in the total vacuum of space is a little different from our experience on earth. The temperature in a fuel tank is very different depending upon whether it is painted black and exposed to the sun or whether it is covered in a highly reflective material and shaded According to Wikipedia, a large ceramic-cloth sunshade, measuring 2.5 m (8.2 ft) tall and 2 m (6.6 ft) wide, is provided for passive thermal control... Main propulsion is via the bipropellant (hydrazine and nitrogen tetroxide) the "LVA" (large velocity adjust) thruster; the spacecraft carried 607.8 kilograms (1,340 lb) of propellant and pressurizer (helium). (In any case, since the propellant is packaged in a sealed container, there is nothing for it to react with until it is released.)

prabhakar_deosthali
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re: Space Log: Messenger arrives at Mercury
prabhakar_deosthali   3/26/2011 10:59:05 AM
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I am just curious to know what kind of fuel is used to propel messenger which can sustain such high temperatures for such a long time. Or is the fuel tank completely shielded from exposure to such high temperatures?

selinz
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re: Space Log: Messenger arrives at Mercury
selinz   3/24/2011 9:08:41 PM
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As engineers, we go through calculations and simulations to solve a problem. This is at a level that leaves little room for error. My hat's off to NASA for getting it right!

george.leopold
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re: Space Log: Messenger arrives at Mercury
george.leopold   3/24/2011 7:29:02 PM
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A key research goal for the Messenger probe (thanks DrQuine for elaborating on the name) is to determine why Mercury is so dense and whether it was once much larger. That will tell us much more about how the solar system was formed. Instrument checkout is continuing, and Messenger's operators are still expected to start poking and probing Mercury beginning in early April.

Sanjib.A
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CEO
re: Space Log: Messenger arrives at Mercury
Sanjib.A   3/24/2011 5:48:29 PM
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Ok I see...thanks for educating me on the subject. What is the highest temperature the Messenger is going to see and how long?

DrQuine
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CEO
re: Space Log: Messenger arrives at Mercury
DrQuine   3/24/2011 11:30:26 AM
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The MESSENGER mission is to orbit the planet not to land. "MESSENGER's orbit is highly elliptical, taking it within 200 kilometers (120 mi) of Mercury's surface and then 15,000 km (9,300 mi) away from it every twelve hours. This orbit was chosen to shield the probe from Mercury's highest temperatures." [Wikipedia's detailed article is being updated as the flight continues; the primary data gathering mission is currently scheduled to start on April 4th: http://en.wikipedia.org/wiki/MESSENGER_spacecraft#Orbital_encounter_with_Mercury ]

Sanjib.A
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CEO
re: Space Log: Messenger arrives at Mercury
Sanjib.A   3/24/2011 4:19:42 AM
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@DrQuine, thanks! I was watching a TV program about Mercury & Venus on National Geography channel and learned that one Mercurian day is equivalent to almost 3-months on Earth. This is because the planet is rotating very slowly on its axis. So depending on where on Mercury the Messenger is dropped, it will see similar kind of temperature for long time. Most likely it has to be on the side facing the sun, otherwise the solar panels won't work. I'd consider it as a great success even if it survives for a few days. Interested to learn how the cooling system was designed back in 2004 :)

DrQuine
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CEO
re: Space Log: Messenger arrives at Mercury
DrQuine   3/23/2011 6:23:30 PM
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The mean surface temperature of Mercury is 443 K (338 deg F), but it ranges from 100 K (negative 280 deg F) to 700 K (800 deg F) due to the absence of an atmosphere and a steep temperature gradient between the equator and the poles. The subsolar point reaches about 700 K (800 deg F) during perihelion then drops to 550 K (530 deg F) at aphelion. On the dark side of the planet, temperatures average 110 K (negative 262 deg F). The intensity of sunlight on Mercury’s surface ranges between 4.59 and 10.61 times the solar constant [thanks to Wikipedia:http://en.wikipedia.org/wiki/Mercury_(planet) with my temperature conversions]

Sanjib.A
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CEO
re: Space Log: Messenger arrives at Mercury
Sanjib.A   3/23/2011 5:36:51 PM
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It is great to witness such a success of the scientists and the engineers. What is the temperature on the surface of the planet that faces the sun for comparatively longer duration than earth? More that 700-800 degF? Can the electronics within “Messenger” survive for a year on Mercury?

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