Relativistic orbital effects
Mercury experiences an element of orbital precession that cannot be predicted using Newton's laws. The General Theory of Relativity does, however, seem to explain the discrepency. Now read about the proximity of a newly-found extra-solar planet to it's star: http://news.yahoo.com/s/nm/20080616/sc_nm/space_planets_dc I'm wondering, without actually doing the math, about the relativistic effects on an orbital period of *4 days! * ** And we say that a year "passes like nothing" here on earth. Ha!
This post reminds me of a fellow I took some programming classes in college with. He was interning for Huges Aircraft, doing a project to calculate liquid fuel sloshing effects on satellite trajectories -- gives me a math headache just thinking about it! --- On Mon, 6/16/08, Chuck Hards <chuck.hards@gmail.com> wrote:
From: Chuck Hards <chuck.hards@gmail.com> Subject: [Utah-astronomy] Relativistic orbital effects To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Date: Monday, June 16, 2008, 11:53 AM Mercury experiences an element of orbital precession that cannot be predicted using Newton's laws. The General Theory of Relativity does, however, seem to explain the discrepency.
Now read about the proximity of a newly-found extra-solar planet to it's star:
http://news.yahoo.com/s/nm/20080616/sc_nm/space_planets_dc
I'm wondering, without actually doing the math, about the relativistic effects on an orbital period of *4 days! * ** And we say that a year "passes like nothing" here on earth. Ha! _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com
Without doing the math, it's still fun to think about. The time frame of reference of a probe landing on such a planet would be out-of-sync with mission control, or another spacecraft orbiting further from the star in a more leisurely orbit. Would the computers on the two craft even be able to communicate with each other? Recall that NASA has had troubles with orbiter-lander communication in the past, thanks to Doppler-shifted lander transmission frequencies induced by velocity. Might relativistic effects pose similar problems? The longer the mission, the further "ahead" in time mission control gets from the probe's frame of reference. How different would a frame dragging have to be, before human perceptions would notice it, let alone computers? Are you reaching for the Excedrin, Rich? *;o) * On Thu, Jun 19, 2008 at 5:06 PM, Richard Tenney <retenney@yahoo.com> wrote:
This post reminds me of a fellow I took some programming classes in college with. He was interning for Huges Aircraft, doing a project to calculate liquid fuel sloshing effects on satellite trajectories -- gives me a math headache just thinking about it!
I just re-watched the Nova episode about Cassini/Huygens. Remember that mission planners did not account for the 12,000 (kph or mph, don't remember which) difference in relative speeds after Huygens was to be launched. Well into the mission they found that Cassini could not "read" the Doppler-shifted radio transmission as it arrived from Huygens. It took six months just to discover why Huygens and Cassini couldn't communicate with each other and another two years(!) to design the fix. They had to do something with Cassini's receiver to adjust for the shifted frequency. Chuck, now you've got me curious to know at what velocities relativistic effects become an issue. I would be surprised to learn if at the velocities of current interplanetary travel relativistic effects make any difference. But that hunch is based on my weak memory of college physics, taken some 30 years ago. (I know, I don't even look that old...) Kim -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Chuck Hards Sent: Friday, June 20, 2008 12:56 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] Relativistic orbital effects Without doing the math, it's still fun to think about. The time frame of reference of a probe landing on such a planet would be out-of-sync with mission control, or another spacecraft orbiting further from the star in a more leisurely orbit. Would the computers on the two craft even be able to communicate with each other? Recall that NASA has had troubles with orbiter-lander communication in the past, thanks to Doppler-shifted lander transmission frequencies induced by velocity. Might relativistic effects pose similar problems? The longer the mission, the further "ahead" in time mission control gets from the probe's frame of reference. How different would a frame dragging have to be, before human perceptions would notice it, let alone computers? Are you reaching for the Excedrin, Rich? *;o) * On Thu, Jun 19, 2008 at 5:06 PM, Richard Tenney <retenney@yahoo.com> wrote:
This post reminds me of a fellow I took some programming classes in college with. He was interning for Huges Aircraft, doing a project to calculate liquid fuel sloshing effects on satellite trajectories -- gives me a math headache just thinking about it!
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com No virus found in this incoming message. Checked by AVG. Version: 7.5.524 / Virus Database: 270.4.1/1510 - Release Date: 6/19/2008 3:21 PM No virus found in this outgoing message. Checked by AVG. Version: 7.5.524 / Virus Database: 270.4.1/1510 - Release Date: 6/19/2008 3:21 PM
Spacecraft comms will get really interesting when we finally have probes that travel at a significant fraction of the speed of light. Imagine having to send your transmissions in the IR or visible range so that your spacecraft can receive it at a specific radio frequency. I imagine that would require a rather high powered laser. Clear skies, Dale
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy- bounces@mailman.xmission.com] On Behalf Of Kim Sent: Friday, June 20, 2008 1:12 PM To: 'Utah Astronomy' Subject: Re: [Utah-astronomy] Relativistic orbital effects
I just re-watched the Nova episode about Cassini/Huygens. Remember that mission planners did not account for the 12,000 (kph or mph, don't remember which) difference in relative speeds after Huygens was to be launched. Well into the mission they found that Cassini could not "read" the Doppler-shifted radio transmission as it arrived from Huygens. It took six months just to discover why Huygens and Cassini couldn't communicate with each other and another two years(!) to design the fix. They had to do something with Cassini's receiver to adjust for the shifted frequency.
Chuck, now you've got me curious to know at what velocities relativistic effects become an issue. I would be surprised to learn if at the velocities of current interplanetary travel relativistic effects make any difference. But that hunch is based on my weak memory of college physics, taken some 30 years ago. (I know, I don't even look that old...)
Kim
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Chuck Hards Sent: Friday, June 20, 2008 12:56 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] Relativistic orbital effects
Without doing the math, it's still fun to think about.
The time frame of reference of a probe landing on such a planet would be out-of-sync with mission control, or another spacecraft orbiting further from the star in a more leisurely orbit. Would the computers on the two craft even be able to communicate with each other?
Recall that NASA has had troubles with orbiter-lander communication in the past, thanks to Doppler-shifted lander transmission frequencies induced by velocity. Might relativistic effects pose similar problems?
The longer the mission, the further "ahead" in time mission control gets from the probe's frame of reference.
How different would a frame dragging have to be, before human perceptions would notice it, let alone computers?
Are you reaching for the Excedrin, Rich? *;o) * On Thu, Jun 19, 2008 at 5:06 PM, Richard Tenney <retenney@yahoo.com> wrote:
This post reminds me of a fellow I took some programming classes in college with. He was interning for Huges Aircraft, doing a project to calculate liquid fuel sloshing effects on satellite trajectories -- gives me a math headache just thinking about it!
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com
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Kim: The Doppler shift is not a relativistic effect actually. It's a result of the finite speed of light travel and can be modeled quite adequately with Newtonian dynamics for any velocity NASA is likely to achieve. The relativistic effects are very interesting though. They depart from the Newtonian values by a quantity called the gama function which is one over the square root of one minus v squared over c squared. 1/sqrt(1-power(v/c),2)) try pluggin it into a spread sheet and playing with different values of v The gama function causes a 10% change from newton at about 40% of c. DT --- On Fri, 6/20/08, Kim <kimharch@cut.net> wrote:
From: Kim <kimharch@cut.net> Subject: Re: [Utah-astronomy] Relativistic orbital effects To: "'Utah Astronomy'" <utah-astronomy@mailman.xmission.com> Date: Friday, June 20, 2008, 12:12 PM I just re-watched the Nova episode about Cassini/Huygens. Remember that mission planners did not account for the 12,000 (kph or mph, don't remember which) difference in relative speeds after Huygens was to be launched. Well into the mission they found that Cassini could not "read" the Doppler-shifted radio transmission as it arrived from Huygens. It took six months just to discover why Huygens and Cassini couldn't communicate with each other and another two years(!) to design the fix. They had to do something with Cassini's receiver to adjust for the shifted frequency.
Chuck, now you've got me curious to know at what velocities relativistic effects become an issue. I would be surprised to learn if at the velocities of current interplanetary travel relativistic effects make any difference. But that hunch is based on my weak memory of college physics, taken some 30 years ago. (I know, I don't even look that old...)
Kim
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Chuck Hards Sent: Friday, June 20, 2008 12:56 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] Relativistic orbital effects
Without doing the math, it's still fun to think about.
The time frame of reference of a probe landing on such a planet would be out-of-sync with mission control, or another spacecraft orbiting further from the star in a more leisurely orbit. Would the computers on the two craft even be able to communicate with each other?
Recall that NASA has had troubles with orbiter-lander communication in the past, thanks to Doppler-shifted lander transmission frequencies induced by velocity. Might relativistic effects pose similar problems?
The longer the mission, the further "ahead" in time mission control gets from the probe's frame of reference.
How different would a frame dragging have to be, before human perceptions would notice it, let alone computers?
Are you reaching for the Excedrin, Rich? *;o) * On Thu, Jun 19, 2008 at 5:06 PM, Richard Tenney <retenney@yahoo.com> wrote:
This post reminds me of a fellow I took some programming classes in college with. He was interning for Huges Aircraft, doing a project to calculate liquid fuel sloshing effects on satellite trajectories -- gives me a math headache just thinking about it!
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com
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Thanks - I know the difference, but I was wondering if at the "low" velocities of today's earth-based spacecraft relativistic effects are even considered when computing orbits, rendezvous, communications, etc. I my try your spreadsheet idea when I have a bit more time. Kim -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of daniel turner Sent: Friday, June 20, 2008 6:58 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] Relativistic orbital effects Kim: The Doppler shift is not a relativistic effect actually. It's a result of the finite speed of light travel and can be modeled quite adequately with Newtonian dynamics for any velocity NASA is likely to achieve. The relativistic effects are very interesting though. They depart from the Newtonian values by a quantity called the gama function which is one over the square root of one minus v squared over c squared. 1/sqrt(1-power(v/c),2)) try pluggin it into a spread sheet and playing with different values of v The gama function causes a 10% change from newton at about 40% of c. DT --- On Fri, 6/20/08, Kim <kimharch@cut.net> wrote:
From: Kim <kimharch@cut.net> Subject: Re: [Utah-astronomy] Relativistic orbital effects To: "'Utah Astronomy'" <utah-astronomy@mailman.xmission.com> Date: Friday, June 20, 2008, 12:12 PM I just re-watched the Nova episode about Cassini/Huygens. Remember that mission planners did not account for the 12,000 (kph or mph, don't remember which) difference in relative speeds after Huygens was to be launched. Well into the mission they found that Cassini could not "read" the Doppler-shifted radio transmission as it arrived from Huygens. It took six months just to discover why Huygens and Cassini couldn't communicate with each other and another two years(!) to design the fix. They had to do something with Cassini's receiver to adjust for the shifted frequency.
Chuck, now you've got me curious to know at what velocities relativistic effects become an issue. I would be surprised to learn if at the velocities of current interplanetary travel relativistic effects make any difference. But that hunch is based on my weak memory of college physics, taken some 30 years ago. (I know, I don't even look that old...)
Kim
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Chuck Hards Sent: Friday, June 20, 2008 12:56 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] Relativistic orbital effects
Without doing the math, it's still fun to think about.
The time frame of reference of a probe landing on such a planet would be out-of-sync with mission control, or another spacecraft orbiting further from the star in a more leisurely orbit. Would the computers on the two craft even be able to communicate with each other?
Recall that NASA has had troubles with orbiter-lander communication in the past, thanks to Doppler-shifted lander transmission frequencies induced by velocity. Might relativistic effects pose similar problems?
The longer the mission, the further "ahead" in time mission control gets from the probe's frame of reference.
How different would a frame dragging have to be, before human perceptions would notice it, let alone computers?
Are you reaching for the Excedrin, Rich? *;o) * On Thu, Jun 19, 2008 at 5:06 PM, Richard Tenney <retenney@yahoo.com> wrote:
This post reminds me of a fellow I took some programming classes in college with. He was interning for Huges Aircraft, doing a project to calculate liquid fuel sloshing effects on satellite trajectories -- gives me a math headache just thinking about it!
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com
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Absolutely- in the case of Mercury's orbit. It demonstrates measurable relativistic orbital precession. That was the model that made me wonder about the 4-day orbital period ("year") of that newly-discovered extra-solar planet. And Kim, Huygens was exactly the spacecraft I was thinking about when I mentioned the doppler-induced frequency shift. Daniel is correct that it's non-relativistic, but it's a robust analogy. On Fri, Jun 20, 2008 at 9:21 PM, Kim <kimharch@cut.net> wrote:
Thanks - I know the difference, but I was wondering if at the "low" velocities of today's earth-based spacecraft relativistic effects are even considered when computing orbits, rendezvous, communications, etc. I my try your spreadsheet idea when I have a bit more time.
participants (5)
-
Chuck Hards -
Dale Hooper -
daniel turner -
Kim -
Richard Tenney