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Dawn Switches Back To Ion Propulsion System


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DazzaMc
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« on: July 06, 2009, 12:08:58 am »

Dawn Switches Back To Ion Propulsion System

Having completed the longest planned coasting period of its entire mission, Dawn is now back to its familiar routine. On June 8, the ion propulsion system was called back into action to propel the probe to its rendezvous with asteroid Vesta.

The spacecraft began its 7-month coast period on October 31, 2008. Since then, it had used its ion thrusters for a measurement of the solar array power, a small adjustment in its course to Mars (the gravitational effect of which provided a boost to its distant destination), and tests of the software remotely installed on the main computer in April.

The accumulated thrusting during all of those activities added only about 10 hours to the mission's log of 282 days when coasting commenced.

Now that the ship has resumed its powered flight, the spacecraft devotes most of its time to thrusting. With the utmost patience, like an artist perfecting each delicate detail in a grand masterpiece, Dawn gradually reshapes its orbit around the Sun. A full day of thrusting is enough only to change its speed by a modest 7 meters/second (less than 16 miles/hour).

Dawn thrusts all but about 6 to 8 hours per week, providing only a brief opportunity to turn away from the direction it needs to aim its ion thruster in order to point its main antenna at Earth. That weekly radio communications session affords the robotic explorer its sole contact with mission controllers.

While it is thrusting, Dawn is programmed to broadcast signals from one of its small, auxiliary antennas, spreading its radio signal in a wide swath that encompasses distant Earth. Usually one of the exquisitely sensitive receivers of NASA's Deep Space Network will listen in on the spacecraft for a few hours halfway through the week, capturing the extraordinarily faint transmission showing the spacecraft is sailing smoothly.

Spending so much time thrusting is possible thanks to the extremely frugal use of xenon propellant. The ion thruster expels only about 0.26 kilograms (10 ounces) in a day. So while Dawn would need nearly 4 days to accelerate from 0 to 60 miles/hour, it would consume little more than 1 kilogram (about 2.3 pounds) of its supply of xenon during that time.

As the probe climbs away from the Sun to reach the cold depths of the asteroid belt, the multiyear thrust profile is designed to make its solar orbit match that of Vesta. The current flight plan has it arriving at the massive protoplanet in September 2011, requiring it to thrust for more than 700 days along the way, the significant majority of the time.

Prior to resuming thrust, the spacecraft carried out a routine check of one its scientific instruments. All of the instruments designed to uncloak the secrets Vesta and Ceres hold about the dawn of the solar system spend most of the time during the interplanetary cruise switched off, waiting for their opportunities to go to work in orbit. Each instrument is powered on occasionally to verify its health.

On May 27, the visible and infrared mapping spectrometer (VIR) was activated. On this occasion, VIR repeated the routines it first executed in space in October 2007. All of its mechanisms were exercised, and they operated smoothly. Instead of aiming at distant celestial targets, its visible and infrared detectors measured emissions from built-in lamps. VIR passed the 4-hour test with flying colors (some of which are outside the range of human vision).

The VIR operation was one of many assignments for the coast period, most of which have been described in logs since November 2008. With all activities completed successfully, the spacecraft set about thrusting right on schedule. On June 8, executing instructions already stored in its main computer, Dawn rotated to point thruster #1 in the required direction. It powered on the ion beam shortly after 11:59 am PDT.

Any readers who happened to be in the vicinity during their own deep-space excursions would immediately have recognized the familiar scene: Dawn majestically perched once again atop a blue-green pillar of xenon ions, as its ambitious journey of exploration continues.

Dawn is 291 million kilometers (181 million miles) from Earth, or 775 times as far as the moon and 1.91 times as far as the Sun. Radio signals, traveling at the universal limit of the speed of light, take 32 minutes to make the round trip.


http://www.spacedaily.com/reports/Dawn_Switches_Back_To_Ion_Propulsion_System_999.html
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donquixotenz
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« Reply #1 on: July 06, 2009, 01:51:32 am »

Sounds positively pornographic!
All that thrusting.
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Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body.

But rather, to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming...

WOW, What a Ride!"

Please note: IMHO and e&oe apply to all my posts.
DazzaMc
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« Reply #2 on: July 06, 2009, 11:45:04 am »

Lol...

These mission take a bloody long time when youre waiting on the results - I had clean forgotten about Dawn!

 Wink
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pantherrr0
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« Reply #3 on: July 07, 2009, 07:40:53 am »

i think its worth adding in  that  while ion systems  accelerate slowly they can keep doing for very very long time  up to  very  high velocities. they  dont  suffer from the  extreme pay load/ fuel / drive (hows that don, no porn) like  chemical or solid fuel rockets do
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DazzaMc
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« Reply #4 on: July 07, 2009, 01:05:32 pm »

In theory they should be able to reach near to the speed of light....  after heaps and HEAPS of thrusting....


And still no porn!

 Grin
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Sir Blodsnogger
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« Reply #5 on: August 26, 2009, 10:47:46 am »

Are we at risk of heareing anything factual around here dazza. Or is it all made up as you go along?
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pantherrr0
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« Reply #6 on: August 26, 2009, 01:18:25 pm »

gom you make it sound like finding out FACTS would be a bad thing ..... oh wait thats completely normal for you isnt it, sigh im sorry  sometimes i do forget that THrusting clenched hand into book face so many times has devastating effects upon the human mind =(    here have a waffle /#/
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Sir Blodsnogger
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« Reply #7 on: August 27, 2009, 04:31:06 am »

That is the problem now that you mention it. There are no facts mentioned here only self worship scientific hypotheses and guesses. Show me just one scientific 'fact' that denies a Creator please.
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pantherrr0
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« Reply #8 on: August 27, 2009, 12:57:46 pm »

photo electric effect, producing electricity from sunlight fact
existance of ions,  molecules  with a chrage  off set from neutral  fact
ions a relativlly small from the entire dawn space ship so due to  the difference in size and newtons laws the acceleration will be slow   fact
you can use a magnetic feild to greatly accelerate an ion  fact
humans predate any signs of religion, fact


humans are not perfect beings so if thier is a creater they are not perfect therefore any creater was not your god
cristianity was built on top of previous religions stealing dates concepts and names to brain wash as many people as possible FACT

its from  this same group  that the idea of this creater has been put forward,  credibility = 0
take intelgent falling' for example another fine piece of work by the same people. if you belive that there is a  creator from this perspective go and jump of a cliff, make it at least 40 metres high onto rocks, dont worry  god will choose not to let you fall =D
from the  book of fairy tales  perspective i do hope  you are stoneing every one that is working on sundays!
and take everything from a literal sense...


now its your turn gom,  you give me facts on why the dawn craft is not  true,  and disprove the basis of its existance and why it wouldnt work, the provide facts on why there is a creator.  whats more it has to be something taht can be independantly tested  so the bible and any of your experiances  are void.
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Sir Blodsnogger
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« Reply #9 on: October 03, 2009, 04:22:33 am »

Just one thing panter
The words are 'in his image' Not 'the same as'.

That should put paid to your silliness bout mankind being the same as God
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DazzaMc
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« Reply #10 on: October 04, 2009, 02:17:44 pm »

Gom... you have a real nack for making me lose interest in what would be an interesting thread...

:-(
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Sir Blodsnogger
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« Reply #11 on: October 05, 2009, 08:29:07 am »

Dont blame me daz
Blame your mate panter for rattling my cage dazza

He made me do it
 Wink
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pantherrr0
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« Reply #12 on: October 05, 2009, 01:36:49 pm »

>.> ill take the blame, i should have known better than to expect any logical debate or self control from gom.

 Was thinking  earlyer  that if the ship passed through patchs of  dust  especially if it was magnetic it would cause a whole lot of problems wouldnt it ? 
 i  guess providing  that its  sheiled at the  front smal dust particles would  just  deflect around it and the propulsion should be un effected. though i wonder what tollerances the drive system has for functioning within an external and probabaly dynamic magnetic feild
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