“due to the movement of a satellite in its orbit”
I thought these were geostationary satellites. Maybe he misspoke and meant the movement of the aircraft?
Garde la Foi, mes amis! Nous nous sommes les sauveurs de la République! Maintenant et Toujours!
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LonePalm, le Républicain du verre cassé (The Broken Glass Republican)
The measurements are exacting enough that they also have to take into account the slight variations in satellite position. There is “movement”.
Even geosync satellites move a little bit. They tend to oscillate in their position, drifting from the south/east quadrant of their “station box” to the northern/western quadrant of their station box over a period of weeks to months.
Every so many months, geosync satellites need to correct this drift in a “station-keeping” procedure which uses small positioning thrusters to put it back into the “lower right” quadrant of their box.
Geosynchronous satellites orbits are not perfect circles so their apparent position wanders north and south of the Equator and they drift east and west in an figure-eight pattern. The position at any instant is monitored by ground stations and the offset of transmitted and received signals is compensated for the Doppler a Effect. Inmarsat was able to refine their model by examining not just the exchange of timing signals with MH370 but also with aircraft flying different know courses, speeds and altitudes over the past few weeks.
You are correct. 3 constellations of 10 satellites orbiting at slightly more than 22,000 miles.
http://searchmobilecomputing.techtarget.com/definition/geostationary-satellite
"...the exact position of a geostationary satellite, relative to the surface, varies slightly over the course of each 24-hour period because of gravitational interaction among the satellite, the earth, the sun, the moon, and the non-terrestrial planets."
Geostationary satellites are moving 1.91 miles per second.
I believe so. Makes sense.
Until they produce some evidence I’ll be standing by. It’s hard to believe any of these reports anymore.
I agree. I basically stated the same a week ago. Eventually something elaborated on the 'ping' at the time, but limited in detail.
It shouldn’t have taken this long. That it did seems suspect to me.
Doppler shift, since they compensate for it, should have been the 2nd thing they did after creating the 'arc' based on the 'ping'. You'd think, anyway.
Definitely odd that it took so long. However, much more plausible than overflying India to Pakistan with impunity and/or undetected...
They are geostationary. Normally Low Earth Orbiting sats can track ground movement with radar using Doppler. Geostationary are 33,000 nautical miles out so this story may be wrong.
They do have very small peroxide thrusters on them to make small corrections as they are needed to maintain its relative position. I know a guy who makes them.
Um, they're still in orbit aren't they? I mean, they don't just hover there in the same place.
But then, what do I know? Maybe, they do.
It is at least somewhat geostationary. I say "somewhat" because the map I've seen shows its ground position a little south of the equator. That would imply that its ground position actually oscillates north and south of the equator over the course of a day. To be truly geostationary, its orbit would have to be in the plane of the equator, and its altitude would have to be such that its orbital period matches the earth's daily rotation time. That would cause it to hang over the same point on the equator all day.
But what matters is not the movement of the satellite — it has to move to stay in orbit — but, rather, the movement of the satellite relative to the airplane.
The new piece of information is that Inmarsat used the Doppler effect to measure the airplane's speed relative to the satellite. I assume that's what McLaughlin meant. The original Inmarsat contribution to the investigation was the plane's distance from the satellite at the hourly ping times. That can be calculated from the ping delay time and the speed of light and narrows the plane's position to a circle on the earth's surface. The Doppler effect would cause the ping's frequency to deviate slightly, allowing the plane's speed towards or away from the satellite also to be calculated.
McLaughlin said they applied the same analysis to normal flights and concluded that the southern part of the arc, not the northern, was where the plane went. Then, of course, there is the fact that none of the countries along the northern arc admit to spotting the airplane on their military radars. And no ransom demands.
Looks like a certain retired three-star is not going to be pleased.