Pioneer P-30
Quote from: Jim on 03/04/2017 10:47 pmPioneer P-30You mean the failed 1960 Atlas-Able lunar probe? You're gonna have to explain that one.... Was its lunar-orbit-insertion engine ignited before it fell back to Earth?
Transit 1B Thor Able-Star
Direct transfer to Jupiter is really high energy. Without stretching the upper stage and perhaps using a kick stage, FH would get very little payload even if fully expendable.
Quote from: Robotbeat on 02/15/2018 05:05 amDirect transfer to Jupiter is really high energy. Without stretching the upper stage and perhaps using a kick stage, FH would get very little payload even if fully expendable.https://en.wikipedia.org/wiki/Hohmann_transfer_orbitaccording to the table in this page, Pluto direct transfer requires even far higher energy
Quote from: Ultrafamicom on 02/15/2018 05:21 amQuote from: Robotbeat on 02/15/2018 05:05 amDirect transfer to Jupiter is really high energy. Without stretching the upper stage and perhaps using a kick stage, FH would get very little payload even if fully expendable.https://en.wikipedia.org/wiki/Hohmann_transfer_orbitaccording to the table in this page, Pluto direct transfer requires even far higher energyA Hohmann transfer orbit is not a direct transfer orbit - https://www.quora.com/What-is-the-hohmann-transfer
One advantage this architecture shares with EML-1 or EML-2 rendezvous is no huge Earth departure stage is needed.
Also compared to EML-1 (respectively EML-2) rendezvous you save ~1.5 km/s (resp. ~0.7 km/s) of delta-vee entering and exiting the Lagrange points.
The second advantage is you don’t have to schedule everything around the moon being in the right place. In particular this should help reach high-declination departure asymptotes, i.e. missions that go in a direction that’s far from being in the plane of the moon's orbit.
Trans-Mars injection delta V is typically several hundred meters per second, depending on the interplanetary C3. Departure from L2 is relatively insensitive to the escape declination because the outbound lunar flyby can change the inclination from near the plane of the Moon into the departure plane. However, the orbital motion of the Moon limits the low delta V escape opportunity to about 3 days, as shown in Figure 2-13. The TMI maneuver should be performed near perigee to keep the delta V minimized, providing a single nearly instantaneous opportunity to depart on the orbit following lunar flyby.
Quote The second advantage is you don’t have to schedule everything around the moon being in the right place. In particular this should help reach high-declination departure asymptotes, i.e. missions that go in a direction that’s far from being in the plane of the moon's orbit.Does this objection apply to high-energy orbits like EML-1/2? The orbital velocity of circular orbits near that of the moon is ~1 km/s. Even a 90 degree plane change from there doesn't sound prohibitive.
Hi,I was wondering how GTO vs GTO- vs GTO+ is defined. From what I have read (and I am no subject matter expert) it would seem that the biggest differentiator is the delta v requirement to GEO from the given transfer orbit. I have seen that -1,800 m/s dv is typical for GTO, -2,200 m/s dv seems to be common for GTO- and -1,500 m/s dv is common for GTO+. Am I right in assuming that a) this is the best way to differentiate between GTO / GTO- / GTO+, and b) if the numbers above are approximately correct.Thanks,Yarg