4 ms·

Is Venus really 27km/s to get to a 400km orbit? I'd have expected a number nearer Earth's

• danw1979 8y ago
  Atmospheric density ? or maybe that the “low orbit” distance given for Venus is 400km vs 250km for Earth.
  • pdonis 8y ago
    > maybe that the “low orbit” distance given for Venus is 400km vs 250km for Earth No, that won't make much of a difference: the gain is basically just the gain in potential energy for the extra 150 km, which is equivalent to only a few tens of meters per second delta-v.
• BenMorganIO 8y ago
  Is that escape velocity or how fast it goes around the sun? I know it's days are exceptionally slow.
• pdonis 8y ago
  I think that delta v includes an extra allowance for the extremely thick atmosphere as compared to Earth's. The delta-v for Earth is given as 9 km/s, which is actually greater than orbital velocity at 250 km altitude; the difference is the extra delta-v you have to allow for atmospheric drag. Venus' atmosphere would give a lot more drag.
  • seszett 8y ago
    On the other hand, the atmosphere of Venus could also been seen as a help since you could "just" float or fly to a great altitude instead of departing from the ground. The ground is pretty much impossible to reach anyway, and not as interesting as the atmosphere about 50 km up, where temperature and pressure are about the same as on Earth and where breathable air is buoyant.
    • pdonis 8y ago
      > the atmosphere of Venus could also been seen as a help since you could "just" float or fly to a great altitude instead of departing from the ground Yes, but I don't think the numbers given in the chart consider such possibilities. I think they're for a standard rocket blasting off from the surface and having to account for atmospheric drag when determining how much delta-v is required to reach orbit.