[meteorite-list] Dawn Journal - November 30, 2010 stupid question

[Steve Dunklee]

Thankyou for your explaination! In a future mission energy can be added to the probe with lasers masers or any other high energy beam to reduce the amount of hydrazine needed  and allow craft to gain energy in areas far from the sun . It would be cheaper to beam it up after launch rather than launch the energy up. I would still like to see NASA or the ESA launch a small bussard ram jet using the hydrogen near the sun as fuel to try to reach near light speed . Every approach of the sun in the right orbit would speed it up by gravity and then use the ions collected near the sun to speed it up even more. It could be done with a small relatively inexpensive probe. The first country to achieve light speed would be similar to the first man on the moon! CHEERS Steve

On Sat Dec 4th, 2010 5:14 PM EST Göran Axelsson wrote:

>The reaction wheels is powered by electricity from the solar panels. The reason (as I understands it) to power down the reaction wheels is to minimize the wear on bearings and motors.
>Using the attitude jets for turning is just another way of aiming the craft. What they have done is simply slowed down the speed it turns. A small acceleration and a small brake takes less fuel than a larger acceleration and a harder brake. It just takes longer time.
>
>For a solar powered spacecraft energy is free, reaction mass is expensive. The hydrazine and xenon is basically the same thing, to xenon energy is added from solar power while hydrazine contains it in it's chemical structure.
>
>/Göran
>
>Steve Dunklee wrote:
>> This might be a stupid question but I was wondering if a future craft similar to this could use the ion propulsion unit to power the reaction wheels. And if the rection wheels or gyros are powered up to full speed before the launch if it could reduce the amount of energy neeeded? In addition a high powered maser could be used for attitude adjustment from earth or space withought using the energy aboard the craft. If designed correctly the craft could be repowered for attitude adjustment indefinately from earth instead of having to launch the energy from earth. Cheers Steve
>> 
>>   
>
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