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Thinking about this a bit more, I realized that you should actually launch 66.184 seconds later by the Orbiter clock since Orbiter clock = CT = UTC + 66.184sec Regards

No, just loot her of her secret treasures. Regards

These statements are correct. I posted this info on the beta testers forum about a year ago so that martin would be aware of it, in case he might want to fix it. Regards

The LCROSS lunar gravity assist does gain relative velocity on impact, but it looks like the important factor is the angle of impact, which you want to be close to 90 degrees, to throw as much stuff up as high as possible. As for the LRO orbit, they are going to correct the orbit periodically...

If you look at the orbital elements of Nix and Hydra with repect to the Pluto body center from Horizons and Spice, there are large fluctuations, mostly because of the presence of Charon, which causes Pluto to move around alot. You get much smaller fluctuations if you look at elements with...

Yes, it still works fine for me. It can be a bit finicky when it comes to parsing the data you give it. In your posted example, I can get it to work correctly if I insert a single space before "A =". It is best to copy and paste the data directly from the e-mail response, which should have that...

This star has been known as a variable since 1846, so it is still variable, what's the news? Regards ref: http://www.aavso.org/vstar/vsots/1200.shtml

Another thing to consider is that the IAU model for Earth may not be all that accurate. A quote from the IAU working group report: " Expressions for the Sun and Earth are given to a similar precision as those of the other bodies of the solar system and are for comparative purposes only." ref...

Pre-precession Orbiter versions assumed that the vernal equinox is fixed in space. In that case, you would want SidRotPeriod to be the period from vernal-equinox to vernal-equinox, so the sun would pass overhead roughly around local noon on the Earth. In that case, the best value to use in...

I agree that the LAN of Earth's equator w.r.t. the ecliptic is 180 degrees in reality, but if you want to have that value in the config file, then Orbiter math would need to be changed, and then the config files for all celestial bodies would also need to reflect that change. Regards...

It depends on what this transformation is supposed to be. I think it should be the transformation from local to ecliptic coordinates, since in the end, you multiply it by the pole vector in local coords (0,1,0) to get the obliquity and LAN with respect to the ecliptic. If that is the case, then...

I've noticed an inconsistency between the description of how rotations are calculated and the actual mathematics that Orbiter uses. You can see it in Figure 1 of the technote, which would imply that for LAN = 0, a positive obliquity would result in the pole vector having a negative z component...

I made a spreadsheet that carries out both the IAU calculation and the Orbiter calculation of precession so I can directly compare the two. I've made some plots of the angle between the rotation axes for the two models. The first plot shows the difference between the two models using the...

I've been trying to model the precession of Triton with the Orbiter precession model, comparing it to data generated by the IAU document and have had good success, if I use L_rel insted of L_ecl in equation 7. I can get the Orbiter model to agree with the IAU model to within 0.09 degrees for...

OK, I think I see what needs to be fixed. With the new precession calculation, SidRotOffset needs to have LAN added to it to compensate for the -L_rel term in the calculation of the rotation angle. If I edit the config, adding LAN to SidRotOffset, everything seems to be OK. Regards

Hi Martin, I've started some testing of the new precession calculations, and I've found what looks to be a bug. If you load up this scenario, you can see what I found. It looks like the body orientation is not being calculated correctly for bodies that do not supply precession data. I've tried...

Going back to an earlier topic, the EPHEM_PARENTBARY problem has been fixed in the latest beta version of Orbiter, so the next public versions should work as expected. Regards

That's the old plan, the current plan is for 7 Venus fly-bys: http://solarprobe.gsfc.nasa.gov/solarprobe_news.htm Regards

The HBO movie "Doomsday Gun" is a very nice accounting (although semi-fictional) of the history (and demise) of Gerald Bull. For any fan of "ballistics-to-orbit", this is a must view. You might find some nice sounds for your project there. Regards

Predicting the trajectory for an aerobraking entry seems to be a bit tricky. The actual landing spot of Phoenix looks to be about 60 km from the planned landing site (but still just within the 99.9 percent "ellipse"), so JPL also had a substantial error in their predictions. Regards