Hi Lee
A common misconception which I've fallen victim to myself. In reality an incoming vehicle falls from Mars's sphere of influence with whatever relative velocity it had before crossing that line and gains hyperbolic velocity before it hits Mars due to Mars's own gravity.
Imagine a relative velocity of -6 km/s relative to Mars's motion around the Sun - that becomes the hyperbolic excess to compute the new orbit within Mars's sphere of influence. Thus in an impact trajectory the impact velocity will be sqrt( 25.2 + 6^2) = 7.823 km/s, which is a bit of a rough ride for a lander. The 25.2 is the square of Mars's surface escape velocity (in km^2/s^2) - and is, of course, lower for a higher periapsis around Mars.
Mars's sphere of influence's radius is the 0.4 power of the mass ratio of Mars/Sun times the Mars-Sun distance. Over the course of its orbit it changes from 0.0035 AU - 0.0042 AU (0.526 - 0.631 million km.)
Likewise for trips to any other planet.
Space/Science » in reply to Falling into Mars.
Ah... no
The whole thread (33 posts)
- No way to land large fast payloads on Mars
- I still think they should revive the original Project Orion
- re: No way to land large fast payloads on Mars
- If only..
- Quite True Currently
- Falling into Mars.
- Did my reply get deleted?
- Nuclear rockets
- Very interesting!
- If it means a brief stopover in martian parking orbit, before descending, I don't see the problem.