Orbiter-Forum [Question] Determing position and orbit for ships in solar orbit ...
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 04-03-2018, 02:10 PM #1 llarian Orbinaut Determing position and orbit for ships in solar orbit ... I am planning a new addon that includes placing six ships/stations in a single solar orbit. The preliiminary orbit design calls for a single orbital plan tilted 1 degree to the ecliptic, 1.6 AU from the sun. The ships will be placed 45 degrees from each other along the orbit. I had originally thought of starting at the First Point of Ares and working my way around. Zo ... how do I determine the orbital elements for such an orbit and for each craft? Thanks in advance.
 04-03-2018, 02:39 PM #2 Face Beta Tester Quote: Originally Posted by llarian  I am planning a new addon that includes placing six ships/stations in a single solar orbit. The preliiminary orbit design calls for a single orbital plan tilted 1 degree to the ecliptic, 1.6 AU from the sun. The ships will be placed 45 degrees from each other along the orbit. I am no trajectory expert, but isn't that done by simply keeping the orbital elements equal except for mean anomaly, which is the angle you increase gradually by 45 degrees (which will make it 8 points around the orbit, not 6)? Mean anomaly vs. true anomaly shouldn't vary too much if the orbit is not too eccentric. According to OrbiterWiki, this is the ELEMENTS format: Quote: Originally Posted by http://www.orbiterwiki.org/wiki/Orbital_elements  ELEMENTS 6731158 0.0004046 51.6412 163.8597 185.4817 215.0447 54745.343391 where 6731158 - Semi-major axis in meters. 0.0004046 - Eccentricity. 51.6412 - Inclination. 163.8597 - Longitude of Ascending Node. 185.4817 - Argument of Periapsis. 215.0447 - Mean Anomaly. 54745.343391 - Epoch in Modified Julian Date. So you could do "ELEMENTS 239400000000 0 1 0 0 <0+n*45> 54745.343391" with 0<=n<=7 . If you want 6 elements, change it to <0+n*60> and go with 0<=n<=5.
 04-03-2018, 04:53 PM #3 Marijn Orbinaut You don't mention a periapsis and apoapsis, only a 1.6AU distance. So I assume you are after a perfect circular orbit. Orbiter's scenario editor needs six values to be set to define an orbit. The first one, the semi-major axis (SMa), can be calucated by summing apogee and perigree and divide these by two. Eccentricity is zero because it's a perfect circle. And inclination is set by you to be 1 degree. This gives you the first three numbers. SMA = (1.6AU + 1.6AU) / 2 = 1.6AU. Ecc = 0 Inc = 1 The other three are for some reason much harder for me to understand. If you think of inclination as tilt, then the fourth value, the longitude of the ascending node (LAN), can be thought of as swivel. The last two values, LPe and eps, define the position of a satellite on the orbital trajectory if I am right. I can't offer a good explanation at this time on how to set or calculate these. Perhaps somebody else can. Usually I go with trial and error from here.

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