20

Your intuition is quite correct. The Hohmann transfer orbit is a bi-tangential orbit, so at the point where the spacecraft leaves Earth, it is travelling in parallel to us. In the case of Mars, we want to travel slightly faster than the Earth in order to lift our aphelion up to the orbit of Mars, meaning we want a little extra velocity on top of the prograde ...


12

According to NASA's history on the mission, Pioneer 11's goals included both investigation of the solar wind outside of the ecliptic, and a look at the polar regions of Jupiter, which appeared to have a more transparent atmosphere than the equatorial regions. A close flyby of Jupiter over either pole would unavoidably sling the spacecraft out of the ecliptic,...


11

What was the duration of the launch window this day? According to Spacelaunchnow, the daily launch window was instantaneous, but there were daily opportunities from July 15 to August 12. Did it first enter a short period of LEO for phasing and/or staging, or did it launch directly into its interplanetary trajectory? From the timeline, it appears that it ...


8

It's using the gravity of Venus alone. Skimming the atmosphere would risk damaging the spacecraft From the NASA blog On Oct. 3, Parker Solar Probe successfully completed its flyby of Venus at a distance of about 1,500 miles during the first Venus gravity assist of the mission. These gravity assists will help the spacecraft tighten its orbit closer and ...


5

The telescope was placed into a heliocentric orbit when its helium supply was depleted On 29 April 2013, ESA announced that Herschel's supply of liquid helium, used to cool the instruments and detectors on board, had been depleted, thus ending its mission. At the time of the announcement, Herschel was approximately 1.5 million km from Earth. Because ...


4

I cannot give you a valid answer for later Missions, but here something about Pioneer and Voyager: As Scientists discover there is a very rare planet constellation in the 70/80ies allowing to pass all large outer planets with one mission, they had been very keen in doing this mission (Voyager). BUT: In fact they have not known if it is possible to cross the ...


4

@Machavity's answer is correct. This is just some addition, interesting data. I had downloaded the data for Parker Solar Probe from Horizons before the launch. They had state vectors for a complete (planned) mission there (Revised: Aug 24, 2018) from launch until 2025-Aug-31 09:19:00. Currently Horizons is showing a much shorter span because it is now based ...


3

Is it possible to combine both approaches to perform flybys to the outer planets and escape the solar system?? Launch it first as if it was a Venus mission which heavily relies on oberth trickery, then use Venus and Earth gravity assists to reach Jupiter, and from there beyond Basically yes. If your main concern is to get to the outer solar system or onto a ...


3

Ideally, trajectory correction maneuvers would never be needed. Ideally, the spacecraft's position/velocity state before and after then coarse maneuver would be known perfectly and instantaneously, and the accumulated delta V applied by the spacecraft would be perfectly applied and perfectly measured. Nearly ideally, the ideal time to perform a trajectory ...


2

The problem with such tools is that they may be considered a national security risk as the principles are similar to those of missiles. However, there are excellent Master theses and PhD dissertations on the topic of optimal control for landing rockets, such as this MSc thesis and this SpaceX paper. These will explain the equations of motion and part of the ...


1

Apollo 11 first entered a 103 nautical mile orbit, and midway through orbit 2 was boosted onto lunar trajectory. This was 2hrs 50mins into the mission, so from this point onwards, mission control were not considering orbits of the Earth. Apollo 11 passed 22k nautical miles at 5hrs and 22 minutes into the mission. 2:54 p.m.- The spacecraft is reported 22,...


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