OT - A long way to go for a short distance

[gregebowman]

They just launched a new Mercury probe. Every source I've read or heard says that it will travel 5 BILLION miles before it reaches the planet closest to the sun. That's funny. It's only 93 million miles from the sun to the earth. So, what is this thing going to do? Go to Pluto first, then go to Mercury? Obviously, no one has checked their facts before someone typed this up and now everyone is quoting this as gospel. 5 Billion miles to Mercury?

[Ragnarok]

Perhaps this explains it:

The spacecraft cannot fly straight to Mercury; it does not carry nearly enough fuel. So it will fly once past Earth, twice past Venus and three times past Mercury for gravity assists — and make 15 loops around the sun — before slowing enough to slip into orbit around the small, hot planet.

I don't know how going around planets that many times will solve the fuel issue unless they use the gravity somehow to slingshot the whole way.

[Thermodyne]

Originally posted by Ragnarok:
Perhaps this explains it:

quote:

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The spacecraft cannot fly straight to Mercury; it does not carry nearly enough fuel. So it will fly once past Earth, twice past Venus and three times past Mercury for gravity assists — and make 15 loops around the sun — before slowing enough to slip into orbit around the small, hot planet.

I don't know how going around planets that many times will solve the fuel issue unless they use the gravity somehow to slingshot the whole way.

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Yep, slingshot is the word that fits best. Saves fuel, and reduces the mass of the craft by getting rid of the engine and fuel tanks. But it only works for non-human missions. Life support is just as heavy as fuel.

[ August 04, 2004, 14:11: Message edited by: Thermodyne ]

[geoschmo]

5 Billion miles sounds about right for all that. It would be more direct to fly straight from here to Mercury, but doing so would take a tremendous amount of fuel as you'd have to decelerate quite a bit to get into orbit. Otherwise it would only have time to snap a few pictures as it zipped by and on out of the solar system, or a firey death as it plunged into the sun.

[geoschmo]

Mercury Mission trajectory WEBSITE

[gregebowman]

Ok, thanks for the info. None of this was mentioned on the news stories that I heard. All I knew was that Mercury was not 5 billion miles from earth. But the slingshot method does sound logical. Hope we get some pretty good pictures in 5-7 years.