> From the Wikipedia article about the Solar Probe+, it seems the spacecraft should achieve 200km/s as it passes by the Sun. At that speed, a trip to Mercury (57.91 million km) would take 80 hours?
If you read the Wikipedia article more closely (https://en.wikipedia.org/wiki/Solar_Probe_Plus) you'll note that it takes seven flybys of Venus over the course of six years to get into that orbit, and the resulting orbit has an 88 day period.
Plus, if you want to do anything more than whiz past Mercury, you need to bleed off that 200km/s speed to orbital velocity, which takes an enormous amount of fuel.
If you read the Wikipedia article more closely (https://en.wikipedia.org/wiki/Solar_Probe_Plus) you'll note that it takes seven flybys of Venus over the course of six years to get into that orbit, and the resulting orbit has an 88 day period.
Plus, if you want to do anything more than whiz past Mercury, you need to bleed off that 200km/s speed to orbital velocity, which takes an enormous amount of fuel.