Hola, space cadets!
from a first generation colony in near Earth orbit. Would it have
email to earth on the journey? How long would it take, say, from Alpha
Centauri? What about voice communication? Video?
Jan
On 7/18/06, janet_baker76 wrote:
(...)
> Say an ark was on the way to Alpha Centauri in a contest, launched
> from a first generation colony in near Earth orbit. Would it have
> email to earth on the journey? How long would it take, say, from Alpha
> Centauri? What about voice communication? Video?
(...)
course it could have audio and video attachments...
on the path there would depend on how far away it was. light can only
travel at light speed and email would likely be delivered by laser to
the ship. you would very much be more likely to receive an email than
a letter as the letter would have to be printed out from a message
received by the ship, which would waste limited resourses. I could be
wrong, but i believe alpha centauri is about 4 light years away, so
the email would be 4 years old by the time you received it. voice and
video would be received the same way.
wrote:
>
> Hola, space cadets!
>
> Say an ark was on the way to Alpha Centauri in a contest, launched
> from a first generation colony in near Earth orbit. Would it have
> email to earth on the journey? How long would it take, say, from
Alpha
The further the transmission, the more power needed to send it at a
particular bandwidth. Even by the outer solar system, our probes send
very slowly. High speed transmission from Alpha Centauri would
require access to massive amounts of power, especially if large
amounts of "personal" email was being sent.
On Jul 18, 2006, at 10:01 AM, janet_baker76 wrote:
Besides the limitation of the speed of light, the basic problem with
transmission is that as distance increases, you have to either reduce
the rate you send data, or increase you power to maintain that rate.
message would probably make it difficult for the colony to send
videos to Earth very often. Earth should be able to send them to the
station, but they would be VERY expensive. Of course, a colony going
to Alpha Centauri would require an enormous power source just to
survive, anyway, so power may not be an issue for them. Even if power
is not a problem, any type of transmission would require the 4.5 year
one-way journey, plus another 4.5 years for a reply. My guess is that
the first few interstellar colonies will have limited communications
due to the massive power requirements for high-bandwidth
transmission, but after a while, antimatter power plants or something
may solve that problem.
If I recall, Alpha centauri is 100,000 times further away than Pluto,
and by the time the Voyagers reached Pluto their transmission rate
had decreased to less than 2K. And you thought dial-up was slow!
doug
On Jul 18, 2006, at 10:01 AM, janet_baker76 wrote:
On 7/18/06, Douglas May wrote:
(...)
> The further the transmission, the more power needed to send it at a
> particular bandwidth. Even by the outer solar system, our probes send
> very slowly. High speed transmission from Alpha Centauri would
> require access to massive amounts of power, especially if large
> amounts of "personal" email was being sent.
(...)
would demand vast amounts of energy, and so I suspect that a little
more for communication would not significantly impact the energetic
requirements of the ship.
Besides, communications can be improved. For instance, probes inside
the solar system would have a way more efficient bandwidth/energy
ratio if they used lasers instead of radio for interplanetary comm.
NASA is already planning to use an interplanetary laser in some
upcoming probe:
http://www.space.com/spacenews/businessmonday_041115.html
Robert, you have made me laugh this morning! I had an image of my
friendly postman Miguel with the missing tooth in the middle of his
big smile on his little scooter winding through the cobbled streets
of --Alpha Centauri!
email, isn't it? You cannot call it a letter without
miscommunicating, unless you are a comedian, which I suspect.
Jan
--- In spacesettlers@yahoogroups.com, "Robert" wrote:
>
> on the path there would depend on how far away it was. light can
only
> travel at light speed and email would likely be delivered by laser
to
> the ship. you would very much be more likely to receive an email
than
> a letter as the letter would have to be printed out from a message
> received by the ship, which would waste limited resourses. I could
be
> wrong, but i believe alpha centauri is about 4 light years away,
so
> the email would be 4 years old by the time you received it. voice
and
> video would be received the same way.
>
> --- In spacesettlers@yahoogroups.com, "janet_baker76"
> wrote:
> >
> > Hola, space cadets!
> >
> > Say an ark was on the way to Alpha Centauri in a contest,
launched
> > from a first generation colony in near Earth orbit. Would it
have
Okay, well, what about the massive amounts of energy available, as
in solar energy? What about energy in space? Is it misleading to
assume or lead others to assume that energy will be, finally for us
humans, abundant?
--- In spacesettlers@yahoogroups.com, Douglas May
>
> The further the transmission, the more power needed to send it at
a
> particular bandwidth. Even by the outer solar system, our probes
send
> very slowly. High speed transmission from Alpha Centauri would
> require access to massive amounts of power, especially if large
> amounts of "personal" email was being sent.
>
> doug
>
> On Jul 18, 2006, at 10:01 AM, janet_baker76 wrote:
>
> > Hola, space cadets!
> >
> > Say an ark was on the way to Alpha Centauri in a contest,
launched
> > from a first generation colony in near Earth orbit. Would it have
> > email to earth on the journey? How long would it take, say, from
Alpha
"And you thought dial-up was slow!"
Jan
--- In spacesettlers@yahoogroups.com, Douglas May
>
> Besides the limitation of the speed of light, the basic problem
with
> transmission is that as distance increases, you have to either
reduce
> the rate you send data, or increase you power to maintain that
rate.
>
> The amount of energy required to send a bandwidth hungry video
> message would probably make it difficult for the colony to send
> videos to Earth very often. Earth should be able to send them to
the
> station, but they would be VERY expensive. Of course, a colony
going
> to Alpha Centauri would require an enormous power source just to
> survive, anyway, so power may not be an issue for them. Even if
power
> is not a problem, any type of transmission would require the 4.5
year
> one-way journey, plus another 4.5 years for a reply. My guess is
that
> the first few interstellar colonies will have limited
communications
> due to the massive power requirements for high-bandwidth
> transmission, but after a while, antimatter power plants or
something
> may solve that problem.
>
> If I recall, Alpha centauri is 100,000 times further away than
Pluto,
> and by the time the Voyagers reached Pluto their transmission
rate
> had decreased to less than 2K. And you thought dial-up was slow!
>
> doug
>
> On Jul 18, 2006, at 10:01 AM, janet_baker76 wrote:
>
> > Hola, space cadets!
> >
> > Say an ark was on the way to Alpha Centauri in a contest,
launched
> > from a first generation colony in near Earth orbit. Would it have
> > email to earth on the journey? How long would it take, say, from
Alpha
On 7/19/06, janet_baker76 wrote:
(...)
> Okay, well, what about the massive amounts of energy available, as
> in solar energy? What about energy in space? Is it misleading to
> assume or lead others to assume that energy will be, finally for us
> humans, abundant?
(...)
abundant resource in the universe, so to speak. However, around Alpha
Centauri (back to our example) yes, the newly arrived habitat would
have in practice free limitless amounts of solar energy around.
Another problem to consider in communicating from system to system is
the interference of the star itself. The closer you approach Alpha
Centauri, the more indistinguishable your signal would be from the noise
of those stars.
lemonade... By intercepting the patterns of interferometry, one may be
able to send a signal that more clearly contrasts the background
'colors' of the stars' noises, and might even be able to leverage such
frequencies as a carrier.
Still, to do so may require the creation of powered relay stations in
line-of-sight between systems. Photoelectric power would require a huge
array, nuclear power may be more feasible if built rugged for long
burning life, but most feasible may be base-beamed power via microwave
or the like.
- joel
janet_baker76 wrote:
Energy requirements wouldn't necessarily have to be as
high as other posters have indicated. If all our
receivers are on earth and the transmission must be
pinpointed to the earth, then yes the signal strength
must be very high at point of origin. If however the
receivers are scattered through the entire solar
system, a much lower power signal can be used to
communicate, as long as the vehicle making the journey
(and transmissions) is not situated directly on a line
between A Cen and a receiver. Reconstructing the
original signal from the ones received by thousands of
antennae outside the orbit of Neptune would be a bit
of a bear, but not an insurmountable task.
--- Lucio de Souza Coelho wrote:
ive been told my joke are a little hard to catch. thanks.
wrote:
>
> Robert, you have made me laugh this morning! I had an image of my
> friendly postman Miguel with the missing tooth in the middle of his
> big smile on his little scooter winding through the cobbled streets
> of --Alpha Centauri!
>
> Dear heart, a "letter" printed out from an emailed message is still
> email, isn't it? You cannot call it a letter without
> miscommunicating, unless you are a comedian, which I suspect.
>
> Jan
>
> --- In spacesettlers@yahoogroups.com, "Robert" wrote:
> >
> > on the path there would depend on how far away it was. light can
> only
> > travel at light speed and email would likely be delivered by
laser
> to
> > the ship. you would very much be more likely to receive an email
> than
> > a letter as the letter would have to be printed out from a
message
> > received by the ship, which would waste limited resourses. I
could
> be
> > wrong, but i believe alpha centauri is about 4 light years away,
> so
> > the email would be 4 years old by the time you received it. voice
> and
> > video would be received the same way.
> >
> > --- In spacesettlers@yahoogroups.com, "janet_baker76"
> > wrote:
> > >
> > > Hola, space cadets!
> > >
> > > Say an ark was on the way to Alpha Centauri in a contest,
> launched
> > > from a first generation colony in near Earth orbit. Would it
> have
> > > email to earth on the journey? How long would it take, say,
from
On Jul 19, 2006, at 12:18 PM, janet_baker76 wrote:
> in solar energy? What about energy in space? Is it misleading to
> assume or lead others to assume that energy will be, finally for us
> humans, abundant?
Solar energy gets exponentially weaker the further you get from the
star. Once you get 1% of the way to Alpha Centauri, you'd pretty much
be in pitch black, darker than the darkest night you've seen on
Earth. The distant stars probably wouldn't illuminate your ship
enough to do repairs while on a space walk, you'd need artificial
lights for that. Many people assume the first energy source to carry
us to the stars will be Nuclear fusion, which is not perfected yet,
but may be in a few years/decades. Nuclear fusion is squishing small
atoms together, while nuclear fission (what we use now) is splitting
large atoms apart. Fusion is safer and yields more energy than
fission, but they haven't developed a viable fusion plant quite yet.
Once they do, some "experts" believe we could make the trip to Alpha
Centauri within a human lifetime (perhaps 50 years one way). At any
rate, no matter how much power you have available, your email/video
transmission would still take 4.5 years one way, and the amount of
data you can send per second would decrease the farther away you get.
Of course now, it could be that the reason SETI hasn't picked up any
alien signals yet is because the aliens have discovered a means of
"faster-than-light" communication, and don't need to use radio. Don't
know of much research going on in that direction, though.
doug
On 7/19/06, Douglas May wrote:
(...)
> Solar energy gets exponentially weaker the further you get from the
> star.
intensity with distance is not exponential, it is in fact a power law.
The inverse of the square law.
> Many people assume the first energy source to carry
> us to the stars will be Nuclear fusion, which is not perfected yet,
> but may be in a few years/decades.
Although of course the same was said 50 years ago, as I can't resist
to remember again and again. ;-) However, you can always use existent
H-Bombs in an Orion type vessel that would be able to reach a few
percent of light speed. (As I remember, Dyson's interstellar Orion
would take 130 years to reach Alpha Centauri.)
On the other hand, in theory you could get something flying at 1% of
lightspeed just using sunlight while you are still close to the Sun
(and then in the destination use Alpha Centauri's light to break). Of
course a trip of four centuries seems a bit too long, but with
biological, non-cryogenic hibernation now looking like a real
possibility, human beings going through hibernation periods running at
1/100 of their normal metabolisms could "see" the voyage as taking
only four years. And then we would have an energetically cheap,
psychologically fast (albeit really slow) way of interstellar travel.
one method that has been discussed in the last few years is to use
solar pumped lasers to push light sails. according to the theroist,
it would be possible to get the ship to several percentages of light,
allowing the trip to be done in less than a life time. theoritically
you could have several lasers in different orbits, each with large
mirrors to capture the last ones beam, sending the energy from the
sun outwards in cascade fashion. each laser would capture the spread
beam of the inward orbital laser then fire a beam outwards. this
would give the effect of the ship being very near the sun well
outside the orbit of pluto. it would be concieveable to get 20, 30 or
even 50 percent of light speed that way.
wrote:
>
> On 7/19/06, Douglas May wrote:
> (...)
> > Solar energy gets exponentially weaker the further you get from
the
> > star.
>
> A picky correction: actually, the law describing the decay of light
> intensity with distance is not exponential, it is in fact a power
law.
> The inverse of the square law.
>
> > Many people assume the first energy source to carry
> > us to the stars will be Nuclear fusion, which is not perfected
yet,
> > but may be in a few years/decades.
>
> Although of course the same was said 50 years ago, as I can't resist
> to remember again and again. ;-) However, you can always use
existent
> H-Bombs in an Orion type vessel that would be able to reach a few
> percent of light speed. (As I remember, Dyson's interstellar Orion
> would take 130 years to reach Alpha Centauri.)
>
> On the other hand, in theory you could get something flying at 1% of
> lightspeed just using sunlight while you are still close to the Sun
> (and then in the destination use Alpha Centauri's light to break).
Of
> course a trip of four centuries seems a bit too long, but with
> biological, non-cryogenic hibernation now looking like a real
> possibility, human beings going through hibernation periods running
at
> 1/100 of their normal metabolisms could "see" the voyage as taking
> only four years. And then we would have an energetically cheap,
> psychologically fast (albeit really slow) way of interstellar
travel.
--- In spacesettlers, "Robert" wrote:
> solar pumped lasers to push light sails. according to the theroist,
> it would be possible to get the ship to several percentages of
> light, allowing the trip to be done in less than a life time.
Robert L. Forward's _Flight of the Dragonfly_. Highly recommended.
"Flight Of The Dragonfly" was the original Analog sci-fi serialization
that Dr. Forward made. He later expanded it the "Rocheworld" series,
following the crew on their way out from Earth and on arrival in the
Barnard's Star system; the later books in the series he did with his
wife and daughter.
the expanded series), he put the power levels from the 1000 solar
pumped lasers in sun-synchronous orbit around Mercury as a bit over
1300 terawatts (~100 times our current electrical power consumption).
By the way, the title "Rocheworld" comes from the French scientist's
name who first worked out the Roche limit; this is the tidal effect that
causes a double-planet system in Forward's universe version of the
Barnard's Star system to share a common atmosphere.
http://en.wikipedia.org/wiki/Roche_limit
Indeed, highly recommended (especially the later books).
Shane
--- In spacesettlers@yahoogroups.com, "Xenophile" wrote:
I might have known that what I bought was the "prototype." Ah, well.
Maybe he doesn't in the main version.
I'd better save up a few book-buying bucks.