Satgen 608 P3D Launch Orbit? by GM4IHJ (BID SGEN608) 2000-11-14 History/Mystery. "A" went splash. Ariane delivered to GEO transfer orbit GTO, but "B" went further than intended in the wrong direction. While "C" was planned for a near Molniya orbit but things changed at the last minute. Where will "D" go ? The next few days and months should be interesting. Phase 3D is scheduled to launch early am 15 Nov 2000 to a GTO at 6.5 degrees inclination, perigee low point 590 kms, apogee either 39122 or 34122 kms. With its 70cm beacon ( probably 435.45 MHz or less likely 435.85 MHz) coming on about 3 hours after separation from the Ariane launcher. This should find the satellite in a near equatorial orbit taking until about 7 or 8 hours after deployment to arrive roughly south of India. At which point it should be receivable in first Eastern then Western Europe . But it will be very low on the Eoropean horizon far to the ESE ( Azimuth circa 100 degrees approx) So how can you be sure that the faint signal you hear is P3D. There is not much opposition around 435.45 MHz. But if the 435.85 beacon is activated, it might be confused with Io26 on 435.822 + or - doppler, or, you could hear someone on Fo20 or Fo29 downlinks 435.8 to 435.9 if they are above your horizon. Though the traffic patterns on these possible QRMers will be quite different from the weak possibly fading , or spin modulated beacon, coming from a P3D omni directional antenna. A better guide to who is who will come from the satellite signal doppler shift. Only elliptical orbiters demonstrate positive increasing frequency doppler shift, for much of their orbit, including that part when the satellite may first come in range of Europe if the satellite launches as planned on the 15th. ( Please note that weather at Kourou sometimes interferes with launches). Near perigee orbit low point P3D should display the familiar negative frequency declining doppler shift so common on LEOsats. But this only applies for 90 to 120 minutes or so around perigee. Then as the satellite starts its slow climb up to Apogee the signal heard should slowly doppler higher and higher. Remember it starts way down below 435.45 , gets to about that frequency at Apogee orbit high point , then continues to climb in frequency even after it passes apogee and begins to return earthwards. In fact it reaches it highest frequency as it approaches the earth on its descent but then as it rounds the earth at perigee the doppler rate of decline is very fierce indeed. Although Europeans should not expect to hear this perigee phase on the first orbit. A second guide to the fact that your are correctly tracking P3D will come from its rate of change of azimuth bearing from your station. Very rapid near perigee , but hardly moving at all near apogee. So lets hope all goes to plan this time. But do not be surprised if it does not. The European window on the first orbit is quite a short one , particularly for Western Europe. But it should be worth searching for if the radio commentaries announce a succesful launch. What ever happens it could be fun. Memories of Oscar 10 . With first G4JJ totally disagreeing with Amsat NA , then others joining in as it became very clear that G4JJ was right . Ao10 had not gone where it was expected to on the first burn of its onboard rocket after release by Ariane.