http://www.floridatoday.com/story/tech/science/satellites-planets/2014/11/27/russian-space-object-baffles-propulsion/19603511/
On May 23, 2014, the Russians launched what has come to be known as Kosmos 2499 from Plesetsk, Russia. Originally designated as Object E, it was considered to be a piece of space debris, cast-off from the main mission.
However, amateur satellite trackers soon established that Object E was no ordinary piece of space debris. Instead of orbiting along the path determined by the Earth's gravity, it had a mind of its own. To deviate from its free-fall path, the satellite had to have some form of propulsion.
One maneuver was to catch up with the booster that put it into orbit. You might think that you speed up to catch up with an object orbiting in front of you. Actually you thrust in the opposite direction. Our earth-bound intuition is confuted when thrusting against the direction of orbital motion causes a satellite to actually speed up.
Not sure I completely understand this article but it has caught my interest. We are always wondering what is up there but not knowing exactly what...
One maneuver was to catch up with the booster that put it into orbit. You might think that you speed up to catch up with an object orbiting in front of you. Actually you thrust in the opposite direction. Our earth-bound intuition is confuted when thrusting against the direction of orbital motion causes a satellite to actually speed up.
Now I am actually confused.
If it were in a circular orbit to begin with, the satellite cannot remain, but now falls into a lower orbit. This actually speeds up the satellite again as it takes a shortcut across the orbital curve. If nothing else is done, the satellite reaches its lowest point, the perigee, at a speed that is too fast to remain in that lower level. It then rises back out of the gravity well, losing speed until it reaches its former altitude, moving slower, but now farther ahead than it would have been on the original circular orbit. The new orbit has the form of an ellipse that is tangent to the original circle. In orbit, the satellite just kisses its old orbit on one side of the Earth at the apogee and reaches its perigee on the opposite side of the Earth.
I think I have this idea and have a slight understanding of this. I need a plain English explanation...maybe an object lesson.
Moving around to different orbits requires a change in velocity — a delta-v. There are several methods that have been used to attain this acceleration. The most obvious is the use of chemical rockets. This is quite effective, but the fuel and oxidizers can be expensive to lift to orbit. The Kosmos 2499 is reported to use Hall Effect thrusters that use electricity to accelerate heavy ions up to higher speeds than chemical rockets can produce. This results in a more mass-efficient means of propulsion.
I have heard of delta V in the old space race.
It is a bit tricky using ions for propulsion, because if you just shoot them out into space, you are left with the electrons sitting on your spaceship and a plume of positive ions out in space. The electrical attraction between opposite charges would quickly reverse the plume and pull it back toward the spacecraft, canceling the thrust they provided on the way out.
The trick is to borrow from Peter to pay Paul. First, take a current of electrons knocking off the outer electrons from neutral atoms, ionizing them. An electrostatic field accelerates the ions up to speed, but before they can escape, new electrons are sprayed back on to the ions, returning them to electrical neutrality. They now can speed off, carrying momentum away from the spacecraft.
The thrust thus formed is small. Only a thin gas is escaping from the thrusters — the weight of a coin like the U.S. quarter, about 60 mN. By comparison, a typical thruster operating at 300 V, 1.5 kW produces a thrust of 83 mN. But even a small force exerted over time is enough to change an orbit.
Speculation was high in a time of international political tension between Russia and the United States. Some people thought it might be an anti-satellite weapon.
A more benign interpretation is that it could be used to capture and deorbit some of the space debris that is increasingly cluttering low Earth orbits.
I am a visual person and it would probably nice if I had a video of the explanation.
Quote from: spacemaverick on November 28, 2014, 06:22:23 PM
One maneuver was to catch up with the booster that put it into orbit. You might think that you speed up to catch up with an object orbiting in front of you. Actually you thrust in the opposite direction. Our earth-bound intuition is confuted when thrusting against the direction of orbital motion causes a satellite to actually speed up.
When you drop closer to earth while travelling at orbital speed your craft will increase in speed.... Star Trek used that principle to sling shot around the sun to increase speed. NASA uses that to speed up spacecraft on far mission.
So if you are dropping orbit and do not want to go TOO fast you would thrust against the orbit direction but you would still gain speed
Not sure I completely understand this article but it has caught my interest. We are always wondering what is up there but not knowing exactly what...
Well here are some of the Russian ships :D This is an older list 8)
(http://www.thelivingmoon.com/45jack_files/04images/Baikonur/big3324.jpe)
Now I am actually confused.
The article is likely a translation... English not so good 8)
QuoteMoving around to different orbits requires a change in velocity — a delta-v.
I have heard of delta V in the old space race.
Delta-v (literally "change in velocity"), NOT to be confused with the Delta V rocket series
QuoteIt is a bit tricky using ions for propulsion, because if you just shoot them out into space,
ION DRIVEDawn is a space probe launched by NASA on September 27, 2007, to study two of the most massive objects of the asteroid belt – the protoplanet Vesta and the dwarf planet Ceres
(http://upload.wikimedia.org/wikipedia/commons/thumb/b/ba/Dawn_Flight_Configuration_2.jpg/1024px-Dawn_Flight_Configuration_2.jpg)
I am a visual person and it would probably nice if I had a video of the explanation.
Naval Space Command thread has a nice video of Orbital Mechanics... that was the video that started my thread
8)
Thanks Zorgon...I wasn't sure where to look but once again you have pointed me in the right direction. I shall look at the section in space command regarding orbital mechanics.
Vesta is one of the proyoplanets, UMLR has mapped for mining. ;D
http://umlr.net/03files/NEO-4-01-0100-000000.html
Zorgon....that video was a great help. I wasn't sure of the subject I was looking for but the video on orbital mechanics was just what I was needing to understand. I have a basic working knowledge now. Thank you.
Good!
Now you can be our Pilot when we get that Pegasus ship commandeered.... errrr built
Then you could live up to your name 8)