Talk:Exploration of Jupiter
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[edit] I'm confused...
...by this:
- "Reaching Jupiter from Earth requires a delta-v of 9.2 km/s,[1] which is comparable to the 9.7 km/s delta-v needed to reach low Earth orbit.[2] Fortunately, gravity assists through planetary flybys..."
The reference http://www2.jpl.nasa.gov/galileo/faqnav.html says "Starting out from a low Earth orbit, a spacecraft needs to increase its speed by 9 kilometers per second (19,440 mph) in order to reach Jupiter" (my italics). Also, as it stands, the word "fortunately" doesn't make sense. It implies that acheiving the stated delta-v for Jupiter is difficult, and yet if it's the same as required for LEO then it can't be that difficult as that operation is very routine. Possibly the difficulty is because the 9.2 km/s is on top of the delta-v needed for LEO, as the reference seems to be saying. Maybe someone who understands this could clarify the text in the article in these respects. Matt 11:07, 6 June 2007 (UTC).
Launching a spacecraft on a direct Jupiter trajectory does requires a great deal of energy. In 2 cases Galileo and Cassini, the on pad mass of the spacecraft were too great to fly a direct trajectory to Jupiter. In other words, no launch system at the time could provide enough delta-V to make a direct flight. If it wasn't for the possibility of gravity assists maneuvers these spacecraft would never have reached Jupiter. So the word Fortunately makes sense in the sense we can still reach Jupiter with a high mass probe using gravity assists.
