Starship Asterisk*

BMAONE23 wrote:

neufer wrote:
One major problem you would have to solve is the need for shielding. As you approach the speed of light you will be heading into an increasingly energetic and intense bombardment of cosmic rays and other particles. After only a few years of 1g acceleration even the cosmic background radiation is Doppler shifted into a lethal heat bath hot enough to melt all known materials.>>

A certain amount of shielding could be provided for through electromagnetism similar to Earths natural dynamo. 1 generator in the front of the ship and a second at the rear (for when you need to turn and decelerate.

BMAONE23 wrote:
As to the Red shifting of Background radiation into lethal heat, I thought that approaching something at a faster rate caused the shifting to be into the ultra violet (blue shift) as you approached it. Seems like you would pass it by before it was shifted into infrared

• At most it becomes Extreme Ultra Violet for intragalactic voyages:

http://math.ucr.edu/home/baez/physics/Relativity/SR/rocket.html wrote:

Code: Select all

    T          t         d          v                γ             CBR
-------------------------------------------------------------------------
    1 year    1.19 yrs  0.56 lyrs  0.77c                 1.58      FIR
    2         3.75      2.90       0.97                  3.99      FIR
    5        83.7      82.7        0.99993              86.2        IR
    8     1,840     1,839          0.9999998         1,895         NIR
   12   113,243   113,242          0.99999999996   116,641         EUV

neufer wrote:
(snip)
One major problem you would have to solve is the need for shielding. As you approach the speed of light you will be heading into an increasingly energetic and intense bombardment of cosmic rays and other particles. After only a few years of 1g acceleration even the cosmic background radiation is Doppler shifted into a lethal heat bath hot enough to melt all known materials.>>

geckzilla wrote:
Haha, derp. I imagined having an extra set of engines on the front and diverting the fuel to them.

http://math.ucr.edu/home/baez/physics/Relativity/SR/rocket.html wrote: The Relativistic Rocket

<<The theory of relativity sets a severe limit to our ability to explore the galaxy in space ships. Given that the galaxy is about 100,000 light years across there seems little hope for us to get very far in galactic terms unless we can overcome our own mortality.

A way to get around the problem may be to use the relativistic effects of time dilation and length contraction to cover large distances within a reasonable time span for those aboard a space ship. If a rocket accelerates at 1g (9.81 m/s2) the crew will experience the equivalent of a gravitational field with the same strength as that on Earth. If this could be maintained for long enough they would eventually receive the benefits of the relativistic effects which improve the effective rate of travel.

In theory you can travel across the galaxy in just 12 years of your own time. If you want to arrive at your destination and stop then you will have to turn your rocket around half way and decelerate at 1g. In that case it will take nearly twice as long in terms of proper time T for the longer journeys.

Here are some of the times you will age when journeying to a few well known space marks, arriving at low speed:

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4.3 ly        nearest star            3.6 years
27 ly         Vega                    6.6 years
30,000 ly     Center of our galaxy     20 years
2,000,000 ly  Andromeda galaxy         28 years

Sadly there are a few technical difficulties you will have to overcome before you can head off into space. One is to create your propulsion system and generate the fuel. The most efficient theoretical way to propel the rocket is to use a "photon drive". It would convert mass to photons or other massless particles which shoot out the back. Perhaps this may even be technically feasible if we ever produce an antimatter-driven "graser" (gamma ray laser).

Remember that energy is equivalent to mass, so provided mass can be converted to 100% radiation by means of matter-antimatter annihilation, we just want to find the mass M of the fuel required to accelerate the payload m. The next chart shows the amount of fuel needed (M) for every kilogramme of payload (m=1 kg).

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d             Not stopping, sailing past:       M       
4.3 ly        Nearest star                      10 kg
27 ly         Vega                              57 kg
30,000 ly     Center of our galaxy              62 tonnes
2,000,000 ly  Andromeda galaxy                  4,100 tonnes

This is a lot of fuel—and remember, we are using a motor that is 100% efficient!

What if we prefer to stop at the destination? We accelerate to the half way point at 1g and then immediately switch the direction of our rocket so that we now decelerate at 1g for the rest of second half of the trip. The calculations here are just a little more involved since the trip is now in two distinct halves (and the equations at the top assume a positive acceleration only). Even so, the answer turns out to have exactly the same form: M/m = exp(aT/c) - 1, except that the proper time T is now almost twice as large as for the non-stop case, since the slowing-down rocket is losing the ageing benefits of relativistic speed. This dramatically increases the amount of fuel needed:

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d             Stopping at:               M       
4.3 ly        Nearest star               38 kg
27 ly         Vega                       886 kg
30,000 ly     Center of our galaxy       955,000 tonnes
2,000,000 ly  Andromeda galaxy           4.2 thousand million tonnes

One major problem you would have to solve is the need for shielding. As you approach the speed of light you will be heading into an increasingly energetic and intense bombardment of cosmic rays and other particles. After only a few years of 1g acceleration even the cosmic background radiation is Doppler shifted into a lethal heat bath hot enough to melt all known materials.>>

geckzilla wrote:With 1G of constant thrust, does that mean halfway there they have to reverse that to 1G of constant deceleration and move all the furniture to the ceiling?

geckzilla wrote:
With 1G of constant thrust, does that mean halfway there they have to reverse that
to 1G of constant deceleration and move all the furniture to the ceiling?

rstevenson wrote:

I don't see how any of this discussion was unreasonable.

Perhaps reasonable wasn't quite the right word. But no discussion of manned exploration of space is treated here with anything except dismissal. However, there are other forums where the nuts and bolts of humans in space are already being discussed in considerable detail, from the engineering aspects to the financial, from the medical to the agricultural, in short term and long term views. So I suggested to Jim that he find such forums to proceed with his discussion. The Asterisk is a wonderful place for other reasons; there's just no place here -- forum space or head space -- for discussing the manned exploration of space.

http://www.asc-csa.gc.ca/eng/50canadaspace.asp wrote:

Click to play embedded YouTube video.

Mc Bob & Doug McKenzie play a key role in raising awareness
about Canada's activities in space and inspiring youth
to explore the fields of science and technology

.

<<On September 29, 2012, Canada will celebrate 50 years of space activities that have propelled it into the ranks of world aerospace leaders. When it launched its first scientific satellite, Alouette I, on September 29, 1962, Canada became the first nation, after the Soviet and American super powers, to design and manufacture its own satellite. The launch marked Canada's entry into the space age, and Canada was recognized by the scientific community as having the most advanced space program at that time.

In the wake of the Alouette's success, the government decided to support space communications and the growth of a Canadian space industry. This led to Canada becoming the first country to develop the following:

A geostationary communications satellite system (Anik satellites);
Earth observation satellites (RADARSAT);
Satellite‑aided search and rescue (SARSAT); and
Space robotics technology (the Canadarms) supplied for NASA Space Shuttles and the International Space Station.

In 2013, with the launch of the hybrid satellite CASSIOPE, Canada will extend its leadership in studying the ionosphere. CASSIOPE will fly a scientific instrument known as the Enhanced Polar Outflow Probe (E-Pop), for the University of Calgary and make a significant contribution to unraveling the mysteries of space weather, which occurs in the ionosphere impacting both satellites in orbit and technology on the ground.

Since 2006, the Government of Canada has invested nearly $8 billion in initiatives supporting science, technology and the growth of innovation firms in Canada, including $5 billion for advanced research, education and training; $2 billion for post-secondary infrastructure; and $1 billion for applied research and financing. This funding has helped to make Canada a world leader in post-secondary education research and to create the knowledge and highly skilled workforce that are required for a more prosperous economy.>>

rstevenson wrote:Perhaps reasonable wasn't quite the right word. But no discussion of manned exploration of space is treated here with anything except dismissal.

I don't see how any of this discussion was unreasonable.

Jim Leff wrote:

neufer wrote:
In that case, I really think that you are being extremely selfish to demand that the public also pays for something vastly more expensive & dangerous than the MSL when the primary motivation appears to be your own personal high.

Holy crap. You're actually serious, aren't you?

Ok, I'm out.

http://www.planetary.org/blogs/emily-lakdawalla/2012/10120819-curiosity-sol65-petrology-jake.html wrote:
First science reports from Curiosity's APXS and ChemCam: Petrology on Jake Matijevic
Posted By Emily Lakdawalla, 2012/10/12

<<Members of the media have been hassling the Curiosity science team for weeks to report some initial results from the use of the ChemCam and APXS to analyze rock compositions. Today, they finally got what they asked for -- but unless you've taken a class in igneous petrology, you'd be hard pressed to explain what those results were, much less what they mean!>>

rstevenson wrote: The people on this forum who are against putting people in space will just gang up on anyone who says otherwise

rstevenson wrote:Aye, there's the rub, Jim! The people on this forum who are against putting people in space will just gang up on anyone who says otherwise, until you (and I) give up talking about it. But of course, there are other forums where reasonable discussion of the issue can take place.

Since Mars is perhaps the only place our current technology can put us and support us...

neufer wrote:In that case, I really think that you are being extremely selfish to demand that the public also pays for something vastly more expensive & dangerous than the MSL when the primary motivation appears to be your own personal high.

Jim Leff wrote:

Chris Peterson wrote: in today's world, I'd be very disappointed in seeing a human being walking on Mars.

There was similar talk during Apollo's development.

And the inspiration delivered by manned exploration (most people don't share your human/silicon inspiration parity) pays its way in greater public interest, which keeps budgets for other space projects healthy.

A certain guy in this discussion http://asterisk.apod.com/viewtopic.php?t=26849&p=167924 put it very articulately:

Chris Peterson wrote:Seriously, there's no chance that money which doesn't go to NASA would ever be used to build a subway line.... It's a mistake to think that you can't invest in space exploration without also investing in other areas of research. And realistically, if we were not spending this money on Mars, I doubt very much we'd be spending it on disease research. That's not really how scientific budgeting, or budgeting in general, works in this country.

Jim Leff wrote:

geckzilla wrote:
Perhaps, Jim, you should ask yourself why our robotic missions fail to inspire you.

What I'm asking myself is where I said any such thing!

Lots of things inspire me, including robotic missions. I stayed up all night for Curiosity's landing, and thrilled at its success. But it was absolutely nothing like seeing a human being set foot on Mars.

Chris Peterson wrote: in today's world, I'd be very disappointed in seeing a human being walking on Mars.

Chris Peterson wrote:Seriously, there's no chance that money which doesn't go to NASA would ever be used to build a subway line.... It's a mistake to think that you can't invest in space exploration without also investing in other areas of research. And realistically, if we were not spending this money on Mars, I doubt very much we'd be spending it on disease research. That's not really how scientific budgeting, or budgeting in general, works in this country.

Jim Leff wrote:Lots of things inspire me, including robotic missions. I stayed up all night for Curiosity's landing, and thrilled at its success. But it was absolutely nothing like seeing a human being set foot on Mars. I never would have imagined that was a debatable point....until this discussion!

geckzilla wrote:Perhaps, Jim, you should ask yourself why our robotic missions fail to inspire you.

StarCuriousAero wrote:

DavidLeodis wrote:The last sentence in the explanation is "Still, estimates indicate that planetary orbits would be stable within the habitable zone of Alpha Cen B, at about half the Earth-Sun distance ..." I wonder if there was intended to be more after "distance" but it got missed out? It just seems an odd ending to the sentence otherwise, as if there should really be a full stop after "distance". Please note that I am not moaning about the writing style, as my query is genuine.

I'm guessing English may not be your original language, so I'll try to explain this:

Ellipses (... or "dot dot dot") can be used at the end of a sentence (or sometimes in the middle) to indicate "trailing off" in thought, in other words, let your own mind or imagination finish the thought for you. Where I believe he was going with this specifically was that you could jump to the conclusion that since it's physically possible for a stable orbit to exist in this system within the habitable "Goldilocks" zone, that there just might be a planet there that meets our own criteria for habitability. Being within the goldilocks zone is by no means the only criteria for habitability though, hence he decided to leave off any conclusion and decided to let the reader wonder about the possibility themselves.

Does that make any sense?