Travel to Stars

[neufer]

A good concept for Unmanned probes. Not so good for manned exploration though, assuming that the purpose of a manned mission would be to stop somewhere, you would have to turn thr ship and blast in front of your direction of travel to slow down thereby traveling through the radiation clouds for 1/2 the trip

The "pusher plate" should provide plenty of radiation protection for the short 10 days deceleration period.

However the ship would have to be much much larger
(especially if it plans to stop when it got back to Earth):

400,000,000 metric ton Super Duper Orion (in orbit)

=> 40,000,000 metric ton flyby payload near α Centauri

=> 4,000,000 metric ton stopped payload at α Centauri

=> 400,000 metric ton flyby payload back near Earth

=> 40,000 metric ton stopped payload back in Earth orbit

(400,000,000 metric ton is on the order of twice the mass of the Great Wall of China)

[Chris Peterson]

A good concept for Unmanned probes. Not so good for manned exploration though, assuming that the purpose of a manned mission would be to stop somewhere, you would have to turn thr ship and blast in front of your direction of travel to slow down thereby traveling through the radiation clouds for 1/2 the trip

I doubt that there will ever be a manned mission to another star. A robotic probe, however, seems within the realm of plausibility.

[neufer]

I doubt that there will ever be a manned mission to another star. A robotic probe, however, seems within the realm of plausibility.

• I volunteer Otto Posterman.

[bystander]

• I volunteer Otto Posterman.

But who would make the APOD posts to Starship Asterisk*?

[neufer]

I volunteer Otto Posterman.

But who would make the APOD posts to Starship Asterisk*?

He could telecommute.

[BMAONE23]

A good concept for Unmanned probes. Not so good for manned exploration though, assuming that the purpose of a manned mission would be to stop somewhere, you would have to turn thr ship and blast in front of your direction of travel to slow down thereby traveling through the radiation clouds for 1/2 the trip

The "pusher plate" should provide plenty of radiation protection for the short 10 days deceleration period.

However the ship would have to be much much larger
(especially if it plans to stop when it got back to Earth):

400,000,000 metric ton Super Duper Orion (in orbit)

=> 40,000,000 metric ton flyby payload near α Centauri

=> 4,000,000 metric ton stopped payload at α Centauri

=> 400,000 metric ton flyby payload back near Earth

=> 40,000 metric ton stopped payload back in Earth orbit

(400,000,000 metric ton is on the order of twice the mass of the Great Wall of China)

This is most unfortunate...as there are only 1,830 tons of Plutonium and 1,900 tons of highly enriched Uranium in the world as of 2005 and only growing at a rate of 70 tons per year.
Not even enough to get half way there
While the world wide known supply is

Location tonnes U percentage of world
Australia---------1,673,000 31%
Kazakhstan--------651,000 12%
Canada-------------485,000 9%
Russia--------------480,000 9%
South Africa ------295,000 5%
Namibia------------284,000 5%
Brazil---------------279,000 5%
Niger---------------272,000 5%
USA-----------------207,000 4%
China---------------171,000 3%
Jordan-------------112,000 2%
Uzbekistan--------111,000 2%
Ukraine------------105,000 2%
India-----------------80,000 1.5%
Mongolia------------49,000 1%
other---------------150,000 3%
World total-------5,404,000

Still a far cry from 400,000,000

Looks like it will be a one way trip

[neufer]

This is most unfortunate...as there are only 1,830 tons of Plutonium and 1,900 tons of highly enriched Uranium in the world as of 2005 and only growing at a rate of 70 tons per year.
Not even enough to get half way there
While the world wide known supply is...5,404,000 tonnes.

Still a far cry from 400,000,000

Looks like it will be a one way trip

333,300,000 metric tons of hydrogen bombs are needed(; the rest is infrastructure).

Only a fraction of these bombs are plutonium-239 or uranium-235.

The primary problem is lofting 400,000 tonnes (much less 400,000,000 tonnes) into orbit.

[saturno2]

Thanks, Neufer for your notes.
Project Orion
A spacecraft driven by thermonuclear energy, would develop a speed of 30,000 Km/sec, would arrive to Alpha Centauri in 44 years)
( to proxima Centauri in 42 years)
Many, many energy and "only " have 10% of light speed

[neufer]

[b][i][color=#0000FF][size=125]Twinkle, twinkle, little bat! How I wonder what you're at! Up above the world you fly, Like a tea tray in the sky.[/size][/color][/i][/b]

---

<<Operation Plumbbob was a series of nuclear tests conducted between May 28 and October 7, 1957, at the Nevada Test Sites.

Operation Plumbbob shaft safety experiments:

• Pascal-A 26 July 1957 Yield: 55 tons
  Pascal-B 27 August 1957 Yield: 300 tons

During the Pascal-B nuclear test, a heavy (900 kg) steel plate cap (a piece of armor plate) was blasted off the top of a test shaft at a speed of more than 66km/second. Before the test, experimental designer Dr. Brownlee had performed a highly approximate calculation that suggested that the nuclear explosion, combined with the specific design of the shaft, would accelerate the plate to six times escape velocity. The plate was never found, but Dr. Brownlee believes that the plate never left the atmosphere (it may even have been vaporized by compression heating of the atmosphere due to its high speed). The calculated velocity was sufficiently interesting that the crew trained a high-speed camera on the plate, which unfortunately only appeared in one frame, but this nevertheless gave a very high lower bound for the speed. After the event, Dr. Robert R. Brownlee described the best estimate of the cover's speed from the photographic evidence as "going like a bat!" The use of a subterranean shaft and nuclear device to propel an object to escape velocity has since been termed a "thunder well". This incident was reputedly used as part of the technical justification for the Orion project for possible use of nuclear blasts for outer-space propulsion.>>

[bystander]

VARIES: The Fastest Starship to Proxima Centauri?
Discovery News | 2012 July 17

[saturno2]

Thanks, Bystander for your link
The new concept of " Varies " ( perhaps) may be a technical solution
to travel to Proxima Centauri in the future.