
NASA’s Kepler Mission Discovers Bigger, Older Cousin to Earth - randomname2
https://www.nasa.gov/press-release/nasa-kepler-mission-discovers-bigger-older-cousin-to-earth
======
throwaway_yy2Di
To help out anyone trying to search for stuff,

* This exoplanet is _now_ "Kepler-452b" (kepler_name),

* In the "Kepler Object of Interest" catalog, it's KOI "K07016.01" (kepoi_name),

* Its star is both K07016 and Kepler ID 8311864 (kepid),

* In the broader 2MASS sky survey, the star has the id "J19440088+4416392"

Sources (catalog search engines),

[http://exoplanetarchive.ipac.caltech.edu/cgi-
bin/TblView/nph...](http://exoplanetarchive.ipac.caltech.edu/cgi-
bin/TblView/nph-tblView?app=ExoTbls&config=keplernames)

[https://archive.stsci.edu/kepler/kic10/search.php](https://archive.stsci.edu/kepler/kic10/search.php)

(edit): Here's a mirror of the Kepler catalog entries -- KIC for the star, KOI
for the planet:

[https://gist.githubusercontent.com/anonymous/deef2bd542224f3...](https://gist.githubusercontent.com/anonymous/deef2bd542224f3a4d9b/raw/69713bafa0c9b1bd454c71ec266946f1ef146a28/gistfile1.txt)

~~~
iso8000
I really like comments that are made to provide some provenance to a _news_
piece. These facts/references should arguably should have been in the text of
the article. Double kudos for providing provenance for your provenance.

------
Gravityloss
The significance is this: it's very likely that there are a lot more such
planets a lot nearer to us. This is because Kepler can only detect planets
which lie in the same plane as earth and the star so the planet occults the
star. Assuming random distribution, there's probably thousand fold amount of
off plane planets.

There are 259 stars within about 30 light years. Communication could be
conceivable with such distances...

[http://joy.chara.gsu.edu/RECONS/TOP100.posted.htm](http://joy.chara.gsu.edu/RECONS/TOP100.posted.htm)

~~~
lovemenot
>> Assuming random distribution (of plane of planets),

Has there been any research on this? I have no actual insight, but I'd guess
the plane of the galaxy would affect plane of stellar rotation and perhaps
also planetary disk alignment.

~~~
Nogwater
I've asked that before too and been told that they are randomly distributed.
Here's a link!

[http://curious.astro.cornell.edu/236-are-the-planes-of-
solar...](http://curious.astro.cornell.edu/236-are-the-planes-of-solar-
systems-aligned-with-the-plane-of-the-galaxy-intermediate)

~~~
mohaine
Thank you. I've been wondering about that for years but never got around to
looking it up.

------
phantarch
At 2 billion years older than Earth, I can't begin to imagine what kinds of
things could possibly be living on this planet. Given, of course, that it's
got the right ingredients for life to arise. What if it's suffered huge
extinctions recently? What if there's a domineering species out to conquer the
planet just like humans? What if there's a society there more sophisticated
than us? It's a very exciting discovery.

~~~
qrendel
I propose it's unlikely that any technological civilizations more advanced
than our own have existed on this planet in the past few billion years,
otherwise some subgroup of their species would likely have seeded the local
universe with life (it's only ~1400 lightyears away) and they would be here
instead of us. Unless of course the panspermia hypothesis is correct and that
is indeed where life on Earth came from.

~~~
DuskStar
Apparently it has a diameter 60% larger than that of the Earth, and so if we
assume it has the same density as the Earth it would have about 16m/s^2
gravity on the surface, and an orbital velocity of around 12km/s @ ~1000km (in
comparison to the Earth, where a 1000km circular orbit is closer to 7km/s).

This means that merely achieving orbit would be approximately as difficult as
launching a probe on a Hohmann transfer orbit to Mars is. (Except that such a
launch vehicle would need nearly twice the thrust/weight, cutting down the
mass ratio even further.) It is not unreasonable to think that a species on
such a planet would have never seriously developed space travel.

~~~
qrendel
To colonize or seed life you don't need to launch huge space vehicles with
enough life support to maintain a breeding population, though. You can just
launch some kind of self-replicating microbes capable of directing themselves
into the forms of life you want to encourage over time. The precise ability to
do this would depend on your current state of technology, but we're pretty
close to developing full blown synthetic biology and genetic engineering
ourselves, so it's hard to imagine they'd need to be more than a few hundred
years more advanced than us at most. Microbes can be engineered to be immune
to most dangers from space travel as well, similar to tardigrades.

To head off the common rebuttal of "maybe they wouldn't have any interest in
it," with more advanced technology smaller and smaller groups of individuals
would be capable of instituting such a project, to the point where any high
school kid with a synthetic biology kit and some toy rocketry kits could
colonize the entire universe (owing to relativistic effects). You'd have to
assume their society underwent some kind of massive convergence of social
norms away from any individuality such that no few members of their species
ever had both the capability and desire.

The entire plan is mostly laid out by: [http://www.tedxvienna.at/watch/why-
aim-for-the-stars-when-th...](http://www.tedxvienna.at/watch/why-aim-for-the-
stars-when-the-galaxies-are-just-as-easy-stuart-armstrong-tedxvienna/)

~~~
javert
You seem to be assuming a notion of continual human progress. In a few hundred
years, we'll probably be in another Dark Age, judging by current trends. We're
like the Roman Empire in 200 AD.

Progress is the exception, not the rule, so far in human history.

~~~
deciplex
> _Progress is the exception, not the rule, so far in human history._

You're either cherry-picking your intervals or have a very weird definition of
"progress".

------
cstross
I want answers to three questions before I get excited:

1\. Does it have active plate tectonics?

2\. Does it have a working deep carbon cycle?

3\. Has its atmosphere hung on to its hydrogen (that is, has it managed not to
lose it all to high-altitude UV splitting and solar wind)?

If the answer to all three of those is "yes" then this suddenly gets a _lot_
more interesting, whether or not we can see any free oxygen in the atmosphere.
And while we won't be able to get answers to them using current technology,
next-generation direct-observation planet seeking telescopes might be able to
deliver within the 15-30 year time scale (if the astrophysicists I know are
correct).

~~~
unchocked
How would the physics of those three observations work, and what angular
resolution would be required? I can see spectroscopy working for #3 and #2, #1
stumps me.

~~~
danieltillett
In theory #1 could be answered by looking for an atmosphere temperature that
are similar to Earth’s despite being in an orbit that should make the planet
cooler. If there is no plate tectonics then all the CO2 gets locked up in
carbonates and the temperature falls (e.g. Mars) or you get a run away
greenhouse like Venus. It is plate tectonics that have kept earth in the
habitable zone. In theory we should be able to detect such a temp delta.

------
cletus
Personally I find this discovery rather sobering.

It's becoming increasingly clear that solar systems are quite common. As our
planet detection abilities increase to smaller and smaller planets I believe
we'll find more and more of those too. Some of these (like this one) will be
in the habitable zone of a star. Some of those assumedly will develop life.
Some of those will develop sentient life.

I just picture a timeline like Earth's projected on this planet, which of
course has no basis in fact. But imagine a civilization that's had _2 billion_
years of life longer than ours?

That's a really long time obviously. It's hard to imagine that such a
civilization couldn't develop automated methods to populate the local space
around them. This is one of the counterarguments to life being common in the
universe of course. At 1% of the speed of light you could populate the galaxy
with autonomous robots in a "mere" 10 million years.

So our inability to detect anything like this gives weight to the argument
that no such starfaring civilization exists or that they're less than ~10
milllion years old.

Was there civilization on this planet and it died out for some reason? We'll
probably never know.

As these planets mount up (as I believe they will), it'll further strengthen
the idea that we're basically doomed (ie the Great Filter) and further suggest
we are a mere cosmic blink.

------
aidos
Live audio here
[http://www.nasa.gov/news/media/newsaudio/index.html?2015-07-...](http://www.nasa.gov/news/media/newsaudio/index.html?2015-07-23)

And slides here (currently on Figure 10)
[http://www.nasa.gov/keplerbriefing0723](http://www.nasa.gov/keplerbriefing0723)

EDIT booooo - audio stream has gone down

EDIT yay!

~~~
myth_buster
The slides (specially #5/9/11) gives a very good info for people to understand
the significance.

    
    
      The size and extent of the habitable zone of Kepler-452 
      is nearly the same as that of the sun, but is slightly bigger because 
      Kepler-452 is somewhat older, bigger and brighter. The size of the orbit of 
      Kepler-452b is nearly the same as that of the Earth at 1.05 AU. Kepler-452b 
      orbits its star once every 385 days.
    

Close to 300K people tuning in!

~~~
jdavid
My viewer says 4.3K

------
jpreiland
To rephrase another comment in the other submission - how do we know/can we
infer so much about a planet so far away when we are just now getting
reasonable pictures of Pluto?

Looking at the images (aside from the artist interpretation), it looks like
they're just guessing based on size and location?

~~~
peeters
One thing to keep in mind is that there is one thing that happens with
exoplanets that can never happen with Pluto: the planet can pass between its
star and us (i.e. eclipse the star). This gives a lot of information about the
planet's composition, because light from the star will scatter/change color
according to the planet's composition. See this image:
[http://seagerexoplanets.mit.edu/images/transitschematic.gif](http://seagerexoplanets.mit.edu/images/transitschematic.gif).

Now maybe you can do that with Pluto using some far-off star for reference,
not sure. Also, I'm not sure if in this specific example the exoplanet made a
transit of its star, or if it was detected by other means (usually by
measuring its gravitational affect on the star, i.e. its star "wobbles").

~~~
privong
> Now maybe you can do that with Pluto using some far-off star for reference,
> not sure.

It has been done for Pluto, first in 1988, with an occultation of a background
star[0].

[0] [http://www.space.com/29885-pluto-atmosphere-to-be-
revealed-b...](http://www.space.com/29885-pluto-atmosphere-to-be-revealed-by-
nasa-new-horizons-spacecraft.html)

~~~
goodcanadian
And most recently with SOFIA at the end of June:

[https://sofia.usra.edu/News/news_2015/06_29_15/index.html](https://sofia.usra.edu/News/news_2015/06_29_15/index.html)

This will help tie in past and future occultation observations to the New
Horizons data.

------
guiomie
"385-day orbit" ... Can't wait to have to take into consideration different
"year" zone in my code.

~~~
bpicolo
seconds since January 1, 1970 on earth is still a valid strategy : )

~~~
InclinedPlane
Almost, but not quite.

While seconds since Jan 1, 1970 is a perfectly fine system, sadly unixtime has
deviated from that simple definition, due to the introduction of leap-seconds.

------
ilurk
It feels extremely frustrating to know -- not just wonder but to know exactly
where -- that there are planets similar to our own, which have a very high
probability of harboring life, yet to be condemned to never be able to take a
really close look at it.

No FTL travel, no working cryonics, no mind-upload tech. Just harsh reality.

~~~
crocal
Frustrating or motivating? As far as I am concerned, if I live long enough to
get even a blurry image of an exoplanet, I will die happy. And the best part:
I have a good chance of this happening:
[http://exep.jpl.nasa.gov/presentations/AIAA_Space_2014Blackw...](http://exep.jpl.nasa.gov/presentations/AIAA_Space_2014Blackwoood%20_%20final.pdf)

~~~
Mahn
Not saying that getting an image of an exoplanet at all wouldn't be exciting,
but I'd die happier if we could land a rover there.

~~~
elwell
Maybe the happiness is in the hope. Is there anything you would find there
that would actually fulfill you? Maybe it's like when people become rich and
they realize that didn't fill them up.

------
pi-rat
Now, if only NASA would announce that Kepler-452b is full of oil, we would
have warp engines in under a decade.

~~~
IndianAstronaut
Why go that far? Titan, Saturn's moon, is loaded with far more hydrocarbons
than are available on Earth.

~~~
pi-rat
Don't tell that to the politicians! We'll never get to leave the solar-system
if they believe they can have all the oil they'll ever need right here in the
neighbourhood!

~~~
mcdougle
That's probably the next logical step, though, honestly. Not necessarily oil
specifically, but resources in general and even colonization of any nearby
planets/etc. that will allow it.

How did we discover (and begin actually using) the Americas? Christopher
Columbus was sent on a trip to retrieve resources from India. It was a
financial trip, supposed to enrich the government, not an exploratory one.

That's kind of how it's always been. Societies have discovered new people,
lands, and resources by accident while trying to expand their empires
(generally).

Furthermore, as we continue to consume resources and grow our population, we
should probably strive to expand our society to other locations before we
overconsume and overpopulate to the point that it starts to cause problems.

------
king_magic
So wouldn't a good next step be to point a bunch of radio telescopes at this
system and start listening?

~~~
cbhl
IIRC, the amount of radio waves leaking from Earth into space has decreased
substantially over the last few decades. I wouldn't be surprised if energy
efficiency gets to the point where, if a foreign alien civilization notices
radio waves from Earth, by the time they transmit a round-trip back at Earth
we'll have long since stopped leaking terrestrial radio waves by accident into
space.

~~~
dandelany
True, but our radio telescopes have also been improving. The Square Kilometre
Array, under construction in Australia, would supposedly be able to detect "an
airport radar system on a planet 50 light years away". I suspect that an
advanced civilization 500 ly away would still likely leak enough radio for us
to detect it with current or near-future technology.

~~~
mcdougle
Unless their technology developed along a completely different path, and the
concept of radio waves is too foreign to them because they use an altogether
different method of communication that we can't even begin to imagine.

------
phkahler
How big is it? They have 2 numbers:

>> Kepler-452b is 60 percent larger in diameter than Earth and is considered a
super-Earth-size planet.

And then:

>> Kepler-452 is 6 billion years old, 1.5 billion years older than our sun,
has the same temperature, and is 20 percent brighter and has a diameter 10
percent larger.

I noticed the lack of "b" on that second one, but they seem to be talking
about a single planet.

~~~
stephengillie
I think "Kepler-452" is the star, and "b" is the 2nd planet in the system. I'm
not certain of their naming convention. Edit: Another poster says "b" is the
1st planet found in the system, regardless of position in the system.

Earth is 12,742 km in diameter, so "b" must be 20,387 km in diameter.

Our Sun is 1,391,684 km in diameter, so Kepler-452 must be 1,530,852 km in
diameter.

Since the star is 10% larger and 20% brighter, but the same temperature, does
that mean it is burning fuel 20% faster, and will enter its later stages
earlier?

~~~
coldpie
>I think "Kepler-452" is the star, and "b" is the 2nd planet in the system.
I'm not certain of their naming convention.

Yep, you understand it correctly.

~~~
ringshall
I'm not sure this is correct. According to one source[1],

"The name of a newly discovered exoplanet is dependant on the name of the star
which it orbits and also if any other exoplanets orbiting the same host star
have been discovered. The first exoplanet discovered around a star is given
its host star name with ‘b’ appended. The next exoplanet discovered in the
same system gets the letter ‘c’ appended and so on. Planets in multiple planet
systems are always labelled b, c, d… in the order of discovery."

It's not clear to me why they would begin with 'b' instead of 'a', but basing
the order of names on the order of discovery makes intuitive sense. The
largest planets would presumably be discovered first, even though they may be
in the middle zone of their systems (such as in the Solar System).

EDIT: Kepler-26[2] is an example of the named order not matching the distance
from the star. The planets in that system, in order of distance from their
star, are: d, b, c, e

[1] [https://www.paulanthonywilson.com/blog/how-are-exoplanets-
na...](https://www.paulanthonywilson.com/blog/how-are-exoplanets-named-the-
explanation-behind-the-exoplanet-naming-convention/)

[2]
[https://en.wikipedia.org/wiki/Kepler-26](https://en.wikipedia.org/wiki/Kepler-26)

------
krschultz
Kepler has to be one of the most interesting NASA missions in the last few
decades. We always suspected there were thousands of planets, but _knowing_ it
is exciting.

------
TTPrograms
Does anybody know what the path is to performing some kind of spectroscopy on
this planet? Detecting molecules that might indicate life - water, ozone?

~~~
valarauca1
When the planet passes in front of its host star, you can measure the change
in the stars spectrum, the new chemicals that aren't normally present in a
star are assumed to be the planet's.

Telescopes that can do this are still a tiny bit away reality I think.

~~~
goodcanadian
This can be done now with bright enough stars. The trouble is that the stars
in the Kepler field are typically very far away, and thus not really bright
enough to do these sorts of studies. Spectroscopic observations of exoplanets
have occurred with nearer and brighter targets.

------
izend
Due to the diameter being 60% larger than Earth's diameter, Kepler-452b's ESI
score[0] cannot be any higher than 0.85.

It might not be the most earth like exo-planet as Kepler-438b[1] has an ESI
score of 0.88.

[0][https://en.wikipedia.org/wiki/Earth_Similarity_Index](https://en.wikipedia.org/wiki/Earth_Similarity_Index)

[1][https://en.wikipedia.org/wiki/Kepler-438b](https://en.wikipedia.org/wiki/Kepler-438b)

~~~
rqebmm
In the article they mention that Kepler-438b is likely subject to extreme
solar radiation during flares because it's so close to its star. That would
make it poor candidate despite scoring high on the ESI scale.

------
FailMore
What's next??? How do we find out if there is life?

~~~
stormcrowsx
More money spent on science and technology.

~~~
parksy
What benefit could that possibly have for humanity? /s

~~~
jessaustin
We'll learn how big the invasion force is, and when they're likely to arrive.

------
lxfontes
if there is intelligent life there and they point a telescope at us right now,
they would be seeing earth ~ 500 years ago.

"check out this planet, looks like a promising place once we run out of
materials here."

~~~
mbil
The planet is 1,400 light-years away. They'd be seeing earth at around 600AD.

~~~
trhway
by the time our today's signal reaches that planet, we ourselves will already
be there to listen to it :)

~~~
nopassrecover
FTL Travel?

~~~
trhway
of course. We know that it is possible - the light speed is the limit of speed
only in fixed metric space-time, and the Universe itself shows that non-fixed
metric space-time(expansion/contraction) can produce FTL speed - just look at
all those far galaxies running FTL away from us. It is just a "simple" matter
of engineering of local space-time metric geometry changes :)

------
_karthikj
Things like this boosts my thoughts of life out there living alone,
discovering/inventing everything from scratch over and over. While we pride
ourselves on passing the knowledge generation by generation to be where we are
now, imagine if we could learn/share it beyond our planet, solar system,
galaxies.... Long way to go!!

~~~
olq
I wonder if we'll abide the prime directive when the day comes ;)

~~~
krapp
The prime directive is fiction, so probably not.

~~~
_karthikj
Well, we would need something like that pro re nata! :) But the very
possibility is exciting!

------
niels_olson
> 1,400 light-years away

Very cool that we can find it, but I don't think we'll be visiting this one
any time soon...

~~~
mentos
[http://www.universetoday.com/15403/how-long-would-it-take-
to...](http://www.universetoday.com/15403/how-long-would-it-take-to-travel-to-
the-nearest-star/)

~~~
lucozade
So best case about 28,000 years.

Which is a bugger as I'm out that week.

~~~
ionwake
I think there is a theory that we can travel nearly the speed of light , but
yeah even then we are a millennia away :(

~~~
danielweber
If you could accelerate at 1 _g_ , you could reach it in 7 years, in your
reference frame.

~~~
ionwake
Wait for the observer... isnt it.... 1800 / 17.... 100 years.

So that means, a baby could reach the exoplanet, before it dies of old age, on
a spaceship travelling 99% the speed of light, which can theoretically built
right now.

How did you arrive at your calculation of 7 years?

Thanks!

~~~
danielweber
I eyeballed it from here[1], which I should have just linked with my post.

[1]
[http://math.ucr.edu/home/baez/physics/Relativity/SR/rocket.h...](http://math.ucr.edu/home/baez/physics/Relativity/SR/rocket.html)

------
stcredzero
I'm actually more excited about Mars-like terrestrial planets. Mars is large
enough to have geologic activity and ores, yet it's small enough to be quite
easy to get off of and into orbit.

------
scrumper
I had a bigger, older cousin when I was a kid. He was awesome. He showed me
his Playboys and taught me how to shoot.

On a serious note, I'm looking forward to the discovery of a smaller cousin.
That seems to me to be more promising for life: Stuff in water oceans won't
sink as readily, so will be able to absorb more sunlight. Avian species will
find life easier going (predicated on a suitably dense atmosphere). Any
advanced civilizations will have an easier time getting out of its gravity
well, and so on.

~~~
unchocked
Buoyancy is actually increased under high G, as the recent SpaceX failure
illustrated.

------
nirai
for proportion, studying that planet and its sun is like trying to observe a
flea orbiting a ping pong ball floating in space as far away as the moon...

------
humbertomn
It IS great news... But it's terrible to see the media here in Brazil going
like "We're finally close to discover life in another planet" and things like
that... And even worse, people sharing like crazy around the internet, without
even reading it or trying to understand what really was discovered.

EDIT: typing error

~~~
baby
I thought that was why we come on website like HN, to get above the average
kind of discussions. I don't think complaining about normal channels of
discussion is really relevant.

------
jmilloy
The 385 day year is mentioned. What about hours in a day? Do we know that?

~~~
unchocked
Wouldn't be able to tell from the data. The yearly cycle produces a partial
eclipse of the parent star. A day comes from the planet spinning on its axis
and there isn't an actual image of the planet that we could analyse for
varying brightness.

------
Kiter1
What is the statistical probability that a star will have a planetary disk
that Kepler can view edge on and has planets that will occult the star?

~~~
jswhitten
Less than 1%. For every star Kepler has detected a planet around, there's a
hundred more stars in its field of view with planets it can't see.

------
rolilink_
I think the most important issue is:

Are they like us? a civilization that loves going to war and colonize others?
that is the most important thing we need to know.

~~~
idlewords
Are they enough like us be incapable of sustaining a space program?

------
aaronbrethorst
Can anyone show me where Kepler-452b is on a star chart?

~~~
sytelus
Constellation Lyra

Right ascension (α) 18h 46m 35.000s

Declination (δ) +41° 57′ 3.93″

Apparent magnitude (mV) 14.467

------
carsongross
"Where is everybody?" \--Enrico Fermi

------
givan
What are the odds that this is just a sunspot?

------
jajaBinks
Only news such as this has the potential to unite humankind.

------
yadakhov
M class planets.

------
frade33
is there one of me?

------
csense
There was an older article in the #1 slot with well over 200 upvotes and a ton
of comments, but I don't know what happened to it? Perhaps the mods removed it
for some reason?

~~~
mrspeaker
It plummeted down off the front page, and is now a bunch of pages deep:
[https://news.ycombinator.com/item?id=9935198](https://news.ycombinator.com/item?id=9935198)

I guess it hit some metric in the ranking algo!

~~~
mmastrac
It was probably just user-flagged since it was kind of a lightweight
submission.

------
cdz0675
Today NASA, apparently experiencing hard times with budget [1], announces
"let's say" just found exoplanet. With pictures. Awesome high res pictures,
reposted by every media in the world, of an object 1400ly away from Earth. Oh,
uhm... of an object _as it was_ back in 1875.

Photoshop? Sure. For popularization? I wouldn't say. Begging for money? Yeah,
more buzz, more money. From whom?

2 days ago Yuri Milner, Russian oligarch and media magnat, announced 100M$
financement of mission to discover new life. Literally 1 person got all this
money - Stephen Hawking.

Another 100M$, Yura? Davai, at least now you know where to fly!

[1]:
[http://www.slate.com/blogs/bad_astronomy/2014/03/05/nasa_bud...](http://www.slate.com/blogs/bad_astronomy/2014/03/05/nasa_budget_2015_more_cuts_more_politics.html)

------
sktrdie
Meh, given the hype for this press-release, I was hoping for something more
extraordinary frankly. Not that finding other exoplanets isn't amazing, just
that we're all waiting to find out whether we are alone or not in the
universe.

Finding out that other advanced civilizations exist out there would bring such
an amazing new meaning to life. If I could ask for one wish, it would be to
find out if we're alone or not. Somehow knowing we're alone would be a large
one to swallow, but the universe works in ways that it doesn't care about our
feelings.

~~~
uptown
Read: "Where are all the aliens?" [http://qz.com/452452/where-are-all-the-
aliens/](http://qz.com/452452/where-are-all-the-aliens/)

"We’re rare, we’re first, or we’re fucked."

~~~
camikazeg
Can't interstellar travel just be impossible?

~~~
Jweb_Guru
Or at least, highly energy-intensive and fragile (due to problems like cosmic
radiation) to the point of impracticality, particularly when it comes to
something like panspermia (or, for that matter, sending high-energy signals
directly at a planet that doesn't detectably have life from the perspective of
the originating species). This possibility is not weighted _nearly_ highly
enough in most analyses.

~~~
TheOtherHobbes
Interstellar travel is perfectly possible if you're not in a hurry.

Assuming there's no way to sidestep GR, the real problem is the human lifespan
(and attention span.)

If our culture moved at 0.1% of the current rate and we lived a thousand times
as long, a 1400 year round trip wouldn't be problematic.

It's possible to imagine low-energy lifeforms that move that slowly. But they
wouldn't be looking for Earth-like planets to colonise - they'd be looking for
much colder and more stable locations.

And we wouldn't be looking for the right spectroscopic signals to give them
away, because we don't know what they are.

~~~
Jweb_Guru
The problem isn't just sending something (or someone) to another star (though
it would take far longer than 1400 years with any currently plausible
technology and energy expenditure). It's sending something _accurately_ to
another star (can't use too much energy adjusting course, since fractional
additions to weight require tremendously more power) with a payload that's
still operational by the time it gets there. Think about the myriad problems
NASA probes have after just a relative handful of years or so in space.

Also worth noting is that all deep space missions thus far have had to rely on
nuclear power, usually using 238-Pu with a half life of less than 90 years.
With such technology, a well-shielded, self-correcting computer system
traveling at reasonable speeds and energies could not survive too long because
it would simply run out of power. AFAIK, workarounds for this rely on exotic
power sources and unproven physics--it's entirely possible that these don't
pan out, and this provides our "Great Filter."

~~~
stcredzero
There's been some nifty work done on the practicality of electrodynamic
tethers and using them to turn a starship against the galactic magnetic field.
You won't get sci-fi ship maneuverability out of this, but it's useful for
course corrections without having to carry or expend reaction mass.

As far as onboard power sources go, fission seems perfectly cromulent. You
just have to protect those radiators.

~~~
Jweb_Guru
I can only find one source on using tethers in interstellar travel:
[http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/2005021...](http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050215611.pdf).
To quote the article, for energy production:

> Since the tether current is 1,333 amps, ne = 3 X 10‘‘ m-3 and the ship’s
> velocity is 900 km/sec, the effective electron-collector radius is
> approximately 3 13 km.

This appears to have a toroidal-field ramscoop as a prerequisite.

For thrustless turning, a 0.06 degree turn requires a tether 10^3 km long:

> To obtain a six-degree trajectory modification during a 1,400-year journey
> with the tether current assumed, the tether length must be increased by a
> factor of lOOX to equal l0^5 km. This would increase tether mass to 2.7 X
> lo5 kg.

And this is using a reference ship many scientists are skeptical about:

> ...it is assumed here that the primary propulsion for these ships is the
> ultra-thin, space manufactured solar sail unfurled as close to the Sun as
> possible at the perihelion of a parabolic or hyperbolic solar orbit. After
> acceleration to interstellar cruise velocity, it is also assumed that sail
> and cables are wound around the habitat section to provide extra cosmic ray
> shielding. The sail is unfurled again for deceleration at the destination
> star.... since the baseline sailcraft for this analysis is somewhat faster,
> either more advanced sail/cable materials are required or the pre-perihelion
> orbit is hyperbolic.

I'd definitely categorize that under "experimental power sources and unproven
physics." Perhaps you are thinking of a different article?

~~~
stcredzero
I got that from a Robert Forward nonfiction book. The craft he described
didn't have ramscoops, but were lightsail craft.

