Why aren't spacecraft launched from higher altitudes?

Thursday, June 18, 2009

This is a question that often gets asked, and the other day I noticed a very good response to it on Reddit. The short answer is that it's worth more to have a launching platform closer to the equator in order to benefit from the Earth's angular momentum, as it's highest at the equator. This is why the US uses a location in the south (Florida), the EU uses Guyana, Korea and Japan use the south as well...but also note that it's not worth it to have a launching platform in the middle of the ocean as transport costs then skyrocket, which is why the US uses Florida and not Hawaii, Korea uses Goheung and not Jeju-do, Japan uses Kagoshima and not Okinawa.

Ideally it would be best to have a location at the equator with a location easily accessible and of high altitude. In fact, there is a place of that nature: Mount Kilimanjaro.

It's only 3 degrees from the equator, is 5,882 metres in height, and has a flat top. You can also a comparison of it here with other mountains and how tame the slope is to your average mountain. At the same time it's still so high that travellers get altitude sickness, with an atmospheric pressure less than half that at sea level. The only problem is that it's not located in the US or in a major industrialized nation - it's in the middle of nowhere in Tanzania. If the US was located where Tanzania is you can bet they would have already made good use of the mountain.

At the same time though, it's probably not worth it to pursue exotic locations to launch rockets as it is probably more cost-effective to develop combination balloon-rocket launching systems, where a balloon or other craft carries a rocket up to some 20 km or so above the ground, the rocket separates, and then fires to take itself to space. Even all-volunteer companies like JP Aerospace are capable of doing this (but not putting the rocket into orbit) as you can see in this very grainy video.

6 comments:

Anonymous said...

Sellamat Dave !

I don't think it would be a good ideao to launch rockets from Mount Kilimandjaro. Because of global warming, its ice crust is disappearing, causing the destruction of an ecosystem and menacing the drainage of the whole neighbouring. Please, don't add a source of pollution in this beautiful landscape !

Olivier
http://sambahsa.pbworks.com/

데이빛 / Mithridates said...

True, it would never happen. It's not worth the cost in the first place and even building a simple observatory on a mountain is difficult enough.

http://www.ens-newswire.com/ens/aug2006/2006-08-07-04.asp

If Tanzania had been a major industrial power and a city had been nearby the mountain it probably would have been put to use already, but now it's not necessary.

데이빛 / Mithridates said...

One other thought though: areas where rockets are launched are often heavily guarded and few are allowed to enter. Couldn't the argument be made that a few employees and the odd rocket launch would actually be better for the mountain than 25,000 visitors a year walking around on top of the soil?

Anonymous said...
This comment has been removed by a blog administrator.
데이빛 / Mithridates said...

Anonymous: sign in first or leave a url if you want to leave a comment like that. No sense in saying "I've done X" when you won't say who you are.

데이빛 / Mithridates said...

One other thought though: areas where rockets are launched are often heavily guarded and few are allowed to enter. Couldn't the argument be made that a few employees and the odd rocket launch would actually be better for the mountain than 25,000 visitors a year walking around on top of the soil?

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