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What's slowing down the two Voyagers?
I was casually checking the weekly mission data archived he-
http://voyager.jpl.nasa.gov/mission/...orts/index.htm when I noted the velocities of both probes (relative to the Sun) were edging lower by small amounts over the past 8 years: Jan 1996 Voyager 1: 17.4 km/s, Voyager 2: 16.1 km/s Jan 1999 Voayger 1: 17.3 km/s, Voayger 2: 15.9 km/s Jan 2002 Voyager 1: 17.2 km/s, Voyager 2: 15.7 km/s Jan 2004 Voayger 1: 17.2 km/s, Voyager 2: 15.7 km/s Any ideas as to what's causing this slow down anyone? I was expecting no decelerations until we reach the first signs of the theoretical 'Oort Cloud' or some other medium that would equally lead to an extinction of Voyagers' onboard radio telemetry relay by a proportional measure. Is the craft's speed reduction connected in some way with the expected slow down in the speed of the solar wind as it nears the 'termination shock' I wonder... Or is there some hitherto unknown relativistic effect of some kind at play here? Abdul Ahad |
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Abdul Ahad wrote:
I was casually checking the weekly mission data archived he- http://voyager.jpl.nasa.gov/mission/...orts/index.htm when I noted the velocities of both probes (relative to the Sun) were edging lower by small amounts over the past 8 years: Jan 1996 Voyager 1: 17.4 km/s, Voyager 2: 16.1 km/s Jan 1999 Voayger 1: 17.3 km/s, Voayger 2: 15.9 km/s Jan 2002 Voyager 1: 17.2 km/s, Voyager 2: 15.7 km/s Jan 2004 Voayger 1: 17.2 km/s, Voyager 2: 15.7 km/s Any ideas as to what's causing this slow down anyone? The sun's gravity, of course. Paul |
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"Paul F. Dietz" wrote ...
Abdul Ahad wrote: I was casually checking the weekly mission data archived he- http://voyager.jpl.nasa.gov/mission/...orts/index.htm when I noted the velocities of both probes (relative to the Sun) were edging lower by small amounts over the past 8 years: Jan 1996 Voyager 1: 17.4 km/s, Voyager 2: 16.1 km/s Jan 1999 Voayger 1: 17.3 km/s, Voayger 2: 15.9 km/s Jan 2002 Voyager 1: 17.2 km/s, Voyager 2: 15.7 km/s Jan 2004 Voayger 1: 17.2 km/s, Voyager 2: 15.7 km/s Any ideas as to what's causing this slow down anyone? The sun's gravity, of course. I had a look round on Google and came across the following dissertion on gravitational interaction with Voyager. http://makeashorterlink.com/?D2D5231A8 |
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Abdul Ahad wrote:
I was casually checking the weekly mission data archived he- http://voyager.jpl.nasa.gov/mission/...orts/index.htm when I noted the velocities of both probes (relative to the Sun) were edging lower by small amounts over the past 8 years: Jan 1996 Voyager 1: 17.4 km/s, Voyager 2: 16.1 km/s Jan 1999 Voayger 1: 17.3 km/s, Voayger 2: 15.9 km/s Jan 2002 Voyager 1: 17.2 km/s, Voyager 2: 15.7 km/s Jan 2004 Voayger 1: 17.2 km/s, Voyager 2: 15.7 km/s Any ideas as to what's causing this slow down anyone? Gravity (from the Sun) http://scienceworld.wolfram.com/physics/Gravity.html |
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*Paul F. Dietz* wrote:
Abdul Ahad wrote: [snip] I noted the velocities of both probes (relative to the Sun) were edging lower by small amounts over the past 8 years: [snip] Any ideas as to what's causing this slow down anyone? The sun's gravity, of course. More verbosely put as: kinetic energy is being exchanged for gravitional potential energy as each probe climbs out of the Suns gravity well. -- Andrew Urquhart - My reply address is invalid, use: www.andrewu.co.uk/contact/ |
#7
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(Abdul Ahad) wrote in message . com...
I was casually checking the weekly mission data archived he- http://voyager.jpl.nasa.gov/mission/...orts/index.htm when I noted the velocities of both probes (relative to the Sun) were edging lower by small amounts over the past 8 years: Jan 1996 Voyager 1: 17.4 km/s, Voyager 2: 16.1 km/s Jan 1999 Voayger 1: 17.3 km/s, Voayger 2: 15.9 km/s Jan 2002 Voyager 1: 17.2 km/s, Voyager 2: 15.7 km/s Jan 2004 Voayger 1: 17.2 km/s, Voyager 2: 15.7 km/s Any ideas as to what's causing this slow down anyone? I was expecting no decelerations until we reach the first signs of the theoretical 'Oort Cloud' or some other medium that would equally lead to an extinction of Voyagers' onboard radio telemetry relay by a proportional measure. Is the craft's speed reduction connected in some way with the expected slow down in the speed of the solar wind as it nears the 'termination shock' I wonder... Or is there some hitherto unknown relativistic effect of some kind at play here? Abdul Ahad I assume they're still trading kinetic energy for gravitational potential energy. Note no noticeable slow down over the last two years - as they get further away, the rate of KE loss will fall. |
#8
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(Abdul Ahad) wrote in message . com...
I was casually checking the weekly mission data archived he- http://voyager.jpl.nasa.gov/mission/...orts/index.htm when I noted the velocities of both probes (relative to the Sun) were edging lower by small amounts over the past 8 years: Jan 1996 Voyager 1: 17.4 km/s, Voyager 2: 16.1 km/s Jan 1999 Voayger 1: 17.3 km/s, Voayger 2: 15.9 km/s Jan 2002 Voyager 1: 17.2 km/s, Voyager 2: 15.7 km/s Jan 2004 Voayger 1: 17.2 km/s, Voyager 2: 15.7 km/s Any ideas as to what's causing this slow down anyone? Gravity. They are not out of the Sun's influence. Sedna is still in orbit around the Sun, and its perihelion is beyond Pluto, IIRC, not to mention the aphelion Regards Carsten Nielsen Denmark |
#9
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(Abdul Ahad) wrote in message . com...
I was casually checking the weekly mission data archived he- http://voyager.jpl.nasa.gov/mission/...orts/index.htm when I noted the velocities of both probes (relative to the Sun) were edging lower by small amounts over the past 8 years: Jan 1996 Voyager 1: 17.4 km/s, Voyager 2: 16.1 km/s Jan 1999 Voayger 1: 17.3 km/s, Voayger 2: 15.9 km/s Jan 2002 Voyager 1: 17.2 km/s, Voyager 2: 15.7 km/s Jan 2004 Voayger 1: 17.2 km/s, Voyager 2: 15.7 km/s Any ideas as to what's causing this slow down anyone? I was expecting no decelerations until we reach the first signs of the theoretical 'Oort Cloud' or some other medium that would equally lead to an extinction of Voyagers' onboard radio telemetry relay by a proportional measure. Is the craft's speed reduction connected in some way with the expected slow down in the speed of the solar wind as it nears the 'termination shock' I wonder... Or is there some hitherto unknown relativistic effect of some kind at play here? Abdul Ahad Hey Abdul! I think that Voyager is one of the absolute coolest things that humanity has ever done! I've been keeping up with the Mission Status Reports, also. How far they have literally/figuratively traveled since launch in 1977! When they were launched we worried about whether they would survive Jupiter, and MAYBE (if we were REALLY lucky!) one of the two craft would survive long enough for Saturn. We didn't dare dream about the encounters with Uranus and Neptune, or imagine that (almost 27 years since launch!) that we would STILL be receiving great science from BOTH craft! My heart sank when I read in one of the recent Status Reports: "There was one significant outage of 3.1 hours duration on 03/12 [oh, damn - did the transmitter finally quit?] due to rain [whew!] at DSS-65" (the 70-meter big dish Deep Space Network antenna in Spain). We often forget that the Voyager mission has two main hardware components - the satellites on their way to the stars, and the huge antennas of JPL's Deep Space Network (DSN). Only the largest DSN dishes are up to the task of receiving the distant signals from the two Voyagers, which are now about 12.5 light-hours away = 90 AU = 8.5 billion miles = 13.6 billion kilometers. Even the biggest dish antennas are nearing the limits of picking up Voyager's weak and distant signal. The Deep Space Net is preparing to use multiple antennas to further the effective range of the mission. To answer your question, the decrease in velocity is due to nothing fancier than the Sun's gravity. Much like throwing a ball into the air, the Voyagers will continue to be gradually slowed down by the Sun's pull, until they enter the enter the influence of some greater attractor. Over thousands of years Voyagers' path will be a line of very gradual curves, as they are gently pulled by first one star, then another. They will orbit the center of the Milky Way Galaxy in a path similar to the Sun. The Oort Cloud is not a nebula-like cloud of gas, but rather the bunch of comets that orbit the sun in a cloud-like pattern. The Oort Cloud will not have an effect on Voyagers speed unless we have an impact with one of the comets - a VERY unlikely event! While the solar wind has a positive effect (adds to momentum), it is so diffuse at that distance that its impact is essentially not measurable. The Voyagers are not traveling fast enough for relativity to of consequence. If anyone is interested in checking up on an old friend, the Voyager web site is at: http://voyager.jpl.nasa.gov/ ¤ Clear skies & a star to steer by! Michael ¤ ************************************************* ****** Michael Foerster ¤ Pres/Research Lead, Skywatch-GL ¤Solar System Ambassador, NASA's Jet Propulsion Lab ¤Night Sky Net Coordinator, The Starry-Nite Society ¤E-Address: ¤N42°31'13.3" ¤ W83°08'43.2" ¤ 668' ¤ -5 GMT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~ FAMOUS LAST WORDS - A SERIES "Computers in the future may weigh no more than 1.5 tons." Popular Mechanics magazine, forecasting the relentless march of science, 1949 ************************************************* ****** |
#10
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(Abdul Ahad) wrote in message . com...
I was casually checking the weekly mission data archived he- http://voyager.jpl.nasa.gov/mission/...orts/index.htm when I noted the velocities of both probes (relative to the Sun) were edging lower by small amounts over the past 8 years: Jan 1996 Voyager 1: 17.4 km/s, Voyager 2: 16.1 km/s Jan 1999 Voayger 1: 17.3 km/s, Voayger 2: 15.9 km/s Jan 2002 Voyager 1: 17.2 km/s, Voyager 2: 15.7 km/s Jan 2004 Voayger 1: 17.2 km/s, Voyager 2: 15.7 km/s Any ideas as to what's causing this slow down anyone? I was expecting no decelerations until we reach the first signs of the theoretical 'Oort Cloud' or some other medium that would equally lead to an extinction of Voyagers' onboard radio telemetry relay by a proportional measure. Is the craft's speed reduction connected in some way with the expected slow down in the speed of the solar wind as it nears the 'termination shock' I wonder... Or is there some hitherto unknown relativistic effect of some kind at play here? Abdul Ahad Um, gravity? Maybe Kepler's Second law has something to do with this.... |
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