Landing a rocket

Quote: Wizard

Why wouldn't it be easier to use blimps to get tourists into low earth orbit? They could also enjoy the experience for hours as opposed to minutes.

The official Fédération Aéronautique Internationale definition of space is altitudes of 100 km or higher. Airships can only attain altitudes of 40 km give or take. There is not nearly enough air pressure at 100 km to keep anything afloat no matter what the technological advances.


http://zeppelin-nt.de/en/
The new tourism zeppelins that they are building fly at an altitude of 3 kilometers.

For a while in the 1960s the US Air Force used altitude of 50 miles for space. During the X-15 program, 13 flights by eight pilots met the Air Force spaceflight criterion by exceeding the altitude of 50 miles (80 km), thus qualifying the pilots for astronaut status. However only two of those flights exceeded 100 km.

It is generally believed that sub-orbital space tourism will be replaced with orbital space tourism with probably a tenfold increase in customer cost (from hundreds of thousand to millions). The extreme technical problems in the 1960's were associated with landing and taking off from the moon. As there are a handful of people who will gladly pay in the hundreds of millions for a chance to circle the moon, that will be the next step.

Cirque Du Soleil Billionaire Guy Laliberte bought a $35 million ticket to to fly on the Russian International Space Station.

Density, Wizard, density.

Quote: Nareed

We'd have settled Mars by 1900!

I'm thinking like the kind that Richard Branson flies.

Quote: Wizard

I'm thinking like the kind that Richard Branson flies.

Atmosphere pressure drops to
10% of pressure at zero altitude when you hit 15.7 km in altitude
0.1% of pressure at zero altitude when you hit 32.4 km in altitude
1/200,000 when you reach 40 km in altitude

During 2002 an ultra-thin-film balloon named BU60-1 made of polyethylene film 3.4 µm thick with a volume of 60,000 m³ was launched from Sanriku Balloon Center at Ofunato City, Iwate in Japan at 6:35 on May 23, 2002. The balloon ascended at a speed of 260 m per minute and successfully reached the altitude of 53.0 km setting a new world record.



The height record for a manned hot air ballon is 6 km.

There is almost no air pressure at 100 km. No airship can fly at that altitude.

Quote: Pacomartin

There is almost no air pressure at 100 km. No airship can fly at that altitude.

It's not a matter of altitude only. There's speed, too.

In order to get into orbit around the Earth, you need a speed of about 7 kilometers per second. If you don't have it, no matter how high you go, you simply fall back down to Earth.

Now, 8 kps is about 15,750 mph. Try getting that with a balloon.

If altitude were all it took, we'd have colonized the whole Solar System by now.

"Orbit" is falling and missing the ground.

A balloon floats, not falls. It can go up as high as the atmosphere will support it. If sufficient atmosphere extended up to the international space station, you could float baloons up to it. ISS would have a large drag problem at that point.

Quote: Dalex64

"Orbit" is falling and missing the ground.

Exactly.

Quote:

A balloon floats, not falls. It can go up as high as the atmosphere will support it. If sufficient atmosphere extended up to the international space station, you could float baloons up to it. ISS would have a large drag problem at that point.

Also the balloon would be moving slowly relative to the Earth, while the ISS would be going 7.some kilometers per second relative to both. The impact would be catastrophic for all involved.

Highest sky dive is 135,890 feet and it was from a balloon. Not sure if that is highest manned balloon but likely.

It's all moot. A balloon cannot operate in a vacuum, and space, by definition, is virtually a vacuum. All you could do is raise the balloon to an altitude and then launch a rocket from there. Of course you would then have to deal with weight and Newtonian forces at that point, making the whole exercise unattainable.

Quote: Pacomartin

The official Fédération Aéronautique Internationale definition of space is altitudes of 100 km or higher. Airships can only attain altitudes of 40 km give or take.

Quote: kenarman

Highest sky dive is 135,890 feet and it was from a balloon. Not sure if that is highest manned balloon but likely.

135,890 feet = 41.4 kilometers

I wasn't sure if it was also the record for "highest manned balloon" so I stated "40 km give or take" in my post.


But you are looking at roughly a 5th degree polynomial, so to double the height would require a balloon 32 times as large. That would mean that you would require a material significantly thinner so that the balloon itself wouldn't weigh as much.

Quote: Pacomartin

During 2002 an ultra-thin-film balloon named BU60-1 made of polyethylene film 3.4 µm thick with a volume of 60,000 m³ was launched from Sanriku Balloon Center at Ofunato City, Iwate in Japan at 6:35 on May 23, 2002. The balloon ascended at a speed of 260 m per minute and successfully reached the altitude of 53.0 km setting a new world record.

It's amazing that they got a balloon that thin to enclose that volume 60,000 m³ is huge even compared to most buildings. The volume of a balloon with 32X the volume is unthinkable (about 2 million m³ ). In comparison the Boeing Everett Factory, originally built for construction of the 747, is 13.3 million m³ . The superdome is probably 3.5-4.5 million m³ .