VESPA Post #1: Initial Mission Planning (First Steps)
VESPA all started because one day, I decided that Venus was underexplored and that I wanted my fictional space agency, the International Partnered Space Agenda (IPSA), to send a probe there.
With that in mind, I began the formal mission formulation by choosing a baseline launch vehicle. Since this was a IPSA mission, it was fairly obvious to me that only IPSA LVs would be used. For a payload in this mass class, IPSA has two; the Aquarius Block 1 (or just Aquarius B1) and the A-IIA (or Verseau) vehicle family.
At the time, the A-IIA was going through a redesign; so the baseline LV was chosen to be the Aquarius B1. Aquarius has a decent mass margin for any mission (
Silverbird says it gets 50300 kg to LEO, but actual tests in Orbiter show that it can get up to 51000 kg to LEO); the LEO payload for the rocket is 51 mT in the standard “104” configuration (where the "1" means it's a Block 1 vehicle, the "0" represents the lack of any booster stages, and the "4" denotes the # of second stage engines). Additionally, the Aquarius B1 is planned to be in service AT LEAST from 2025-2038.
So now that a launch period had been set, I plugged my initial mission data intro Trajectory Browser.
These are the results. Now, using Silverbird, I individually plugged each departure orbit parameter(s) into Silverbird, to determine how much the 104 could therefore send to Venus.
These are the results (rather than the “104”, this shows the performance of the “102” configuration, but that doesn't matter):
January 2028:
9,901 kg
October 2029:
11,076 kg
May 2031:
11,759 kg
December 2032:
12,062 kg
June 2034:
11,392 kg
January 2036:
10,361 kg
November 2037:
10,299 kg
June 2039:
11,573 kg
The largest probe(s) intended to have gone to another (near-Earth) planet was the Phobos-Grunt spacecraft, weighing over 13,200 kg when launched (though much of this mass was propellant for the Flagman upper stage, to depart LEO). Most probes are far below this limit; Cassini-Huygens, for example, weighs only 5,200 kg, but it is still one of the largest interplanetary probes launched.
Essentially, even the least optimal window is still has plenty of payload margin; for the purposes of the initial VESPA mission planning, the most optimal window was chosen:
The result is the
December 2032 window, which requires about 305 m/s of delta-V for the VOI burn in
May 2033.
Next (detailed?) VESPA Post will focus on the s/c designs. :thumbup:
