# min time a direct ascent ASAT rocket would take to reach GEO [closed]

Trying to work out a rough time estimate for an ASAT rocket to reach GEO height?

• As far as I know, there are none at present, and nothing very similar either, so you'd probably have to do the design yourself. Jan 12 '16 at 5:08
• I'm trying to work out the effect on travel time if rocket is fired directly at target rather than needing to enter a stable orbit. It takes hours for a satellite to reach GEO but if a direct ascent is made does that cut it drastically? - to tens of minutes? or is it still hours?
– Matt
Jan 12 '16 at 5:26
• Assuming you have a rocket that leaves you moving at about 10 km/s practically vertical by the time you are at an altitude of 100 km, you'll coast the rest of the way to GEO in about 6 hours. Jan 12 '16 at 6:25
• Note my numbers are roughly pulled out of the air since you aren't giving us enough details to properly answer the question! Jan 12 '16 at 6:42
• @Matt, you will not be traveling at 10 km/s all the way there, you are starting at that speed and gravity will slow you to a stop just at the point you reach GEO (and then fall back down if you don't have a collision). Just imagine it like you are tossing a ball into the air, it starts with some speed and slows down until reaching the peak and falling back down. Accelerating under propulsive action the entire flight would be a different story, but that is unrealistic in terms of your question and the apparent scope of your work. Jan 13 '16 at 3:40

• Realistically, you cannot simply accelerate as fast as you want. We can talk about exotic warp drives or just ignore size and cost and pretend we can have a giant ASAT vehicle, but for sensible case studies the most you can expect is a high $Delta v$ manoeuvre sending you into a highly elliptic orbit that sends you to GEO altitude. Someone should consider how fast we could accelerate a Delta IV or Falcon 9 (or maybe even a Saturn V) with no payload. Jan 13 '16 at 3:46