APOD: A View from Next Door (2012 Oct 18)

[Chris Peterson]

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.

I think that's a little strong. Those of us generally against manned space exploration could make the same argument! What's wrong with discussion?

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

It's not clear that Mars could support us any easier than the Moon... and the Moon is a lot easier to get to. If we intend some sort of long-term or semi-permanent presence on another body, starting with the Moon would seem sensible.

[Jim Leff]

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

Oh, I don't mind a good argument. Everyone's certainly entitled to a viewpoint, and I enjoy hearing other views. As Chris says, "What's wrong with discussion?"

I just don't like being emotionally shrieked at (especially, weirdly, by someone arguing in favor of a rationalist perspective).

[neufer]

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.

Or you could stay and simply be moderately selfish (like the rest of us here) and demand that the public continue pay for robotic missions like MSL regardless of whether or not THEY themselves can appreciate them very much.

But, at least, we are not as selfish as those snooty igneous petrologists:

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!>>

(And to think that my hard earned tax dollars is paying for their buffet )

[rstevenson]

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.

Rob

[Chris Peterson]

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 that at all. Different people have different views, which are freely expressed here. Do you mean that your ideas about manned exploration are challenged by people who you generally respect and agree with on other matters? Certainly, people who favor manned exploration also find supporters here. No civil discourse on the subject is moderated away. "Disagreement" is not "dismissal".

I happen to consider manned space exploration to not be in the best interests of humanity at the moment. That does not mean I dismiss the opinions of people who feel otherwise, simply that I disagree with them... and why should I not express my ideas on the matter, just as they do?

[neufer]

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.

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.>>

[BMAONE23]

3 technologies that are currently missing for the "Trip Next Door" but would be needed to make the trip a success. Shielding to protect the ship from micrometeoroid impact at high velocities. Shielding to protect the astronauts from Cosmic Radiation in space. Artificial gravity since we are a species which can only thrive in an environment which includes 1G pressure on our skeletal structure to prevent muscle & bone loss.
We don't want to arrive at the star next door and be pools of jelly.
The distance barrier and gravity barrier could be overcome if we could alter our mode of thrust to one which would produce 1G of constant thrust. Problem is maintaining the thrust without depleting fuel supplies and without needing massive fuel supplies

[geckzilla]

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?

[neufer]

Click to play embedded YouTube video.

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?

It means that half way there the spacecraft has to flip over (pitch or yaw 180º).

Moving the furniture is easy compared to moving the rocket engines.

[BMAONE23]

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?

Nah, they only have to power down the engines long enough to rotate the ship 180 deg then back on again for the deceleration phase.
Batten down the hatches and stow the gear, prepare for Zero G rotation deceleration maneuvers

[geckzilla]

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

[neufer]

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

You can't carry extra anything

Every kilogramme of payload will require at least 38 kg of fuel one way and 38x39 kg of fuel for a round trip:

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]

Yes, of course not.

[BMAONE23]

(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.>>

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.

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

[neufer]

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.

Any amount of shielding is going to mean extra payload weight which is highly undesirable.

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

1) They specifically stated "Doppler shifted" which in this case means "blue shift."

2) They have greatly exaggerated the risk of blue shifted CBR.

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

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    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