
NASA finds a large amount of water in an exoplanet's atmosphere - dnetesn
https://www.nasa.gov/feature/goddard/2018/nasa-finds-a-large-amount-of-water-in-an-exoplanets-atmosphere
======
aphextron
Incredibly exciting that these techniques for exoplanet spectroscopy have come
so far so quickly. I have full faith that we will discover indirect chemical
evidence of extraterrestrial life within the next 10 years. Once JWST [0]
comes online it's going to be just a matter of time.

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

~~~
tomrod
What would that indirect chemical evidence look like? Perhaps an example you
have in mind? Outside of non-committal elements like Uranium or something
showing up, I'm not sure what that evidence would look like?

~~~
ranger207
Oxygen would be one. Due to its reactivity, free oxygen is rare, and oxygen
spectra may be evidence of respiration.

~~~
emmelaich
Pretty sure atmospheric oxygen can be produced from weathering of silicon
dioxide.

~~~
aaronblohowiak
Why wouldn’t it get bound up with carbon or iron or aluminum etc etc

------
curiousgal
This might be a dump question but if we were to look at our planet from far
away what exactly would we see?

~~~
elihu
From lightyears away, probably nothing except maybe a slight drop in the sun's
output if the Earth happens to pass in front of it and a periodic wobble of
the sun's location as the sun and Earth orbit the center of gravity of the
sun-Earth system.

The Earth is pretty small and far from the sun compared to the kinds of
exoplanets we've been able to detect, so the wobble (which might be detectable
via doppler shift of light from certain elements in the sun) would be slight
and probably hard to detect without some pretty sophisticated instruments.

It might be possible to detect something the size of the Earth from several
light years away with a good enough telescope, but I'm not sure what the limit
of that is.

~~~
samstave
If we are so small as compared to our sun, and these exoplanets may be so much
larger - and we have the idea of a “habitable zone” for planets: is there a
“habitable gravity” level for planet size that we should consider for
harboring life?

~~~
acqq
There are actualy the limits:

[https://www.forbes.com/sites/startswithabang/2017/02/16/supe...](https://www.forbes.com/sites/startswithabang/2017/02/16/super-
earths-are-common-but-incapable-of-supporting-life-like-ours/)

------
elihu
> In fact, the planet, known as WASP-39b, has three times as much water as
> Saturn does.

Is that a lot?

~~~
BinaryIdiot
That's exactly what I was wondering! It's such an odd choice to compare it to
as I'm having trouble finding an exact number. This article mentions that it's
a small amount of ice but not exactly helpful for a scale:
[https://www.universetoday.com/15374/is-there-water-on-
saturn...](https://www.universetoday.com/15374/is-there-water-on-saturn/)

~~~
ASalazarMX
So there's little water on Saturn! but wait, since Saturn is about 300 times
the size of earth, and Earth's mass is just 1/4000th water, I'm still utterly
confused as how much it is compared to us.

Odd choice, indeed.

~~~
TheSpiceIsLife
Saturn is big! And it looks blue!

Must be _a lot_!

~~~
dclowd9901
Saturn looks blue?
[https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA00400](https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA00400)

~~~
pluma
What blows my mind is that Saturn in that image looks almost exactly like it
does in the intro to Star Trek The Next Generation, which I always chalked up
as bad CGI.

~~~
rbanffy
Consider this image is from Voyager. Cassini captured much higher resolution
ones.

~~~
pluma
Higher res maybe, but it still looks amazingly fake:

[https://saturn.jpl.nasa.gov/resources/7549/?category=amateur...](https://saturn.jpl.nasa.gov/resources/7549/?category=amateur-
images)

I guess what's messing with me is that it just looks so smooth, which life-
long exposure to CGI has taught me to mean that it's fake.

This reminds me of what Elon Musk said about his Tesla in space: you can tell
it's real because it looks so fake.

------
indescions_2018
And only 700 light years away ;) It would be nice to compare the atmospheric
spectrum of WASP-39b. As well as other candidate exoplanets in habitable
zones. With the baseline of our own home planet.

High resolution transmission spectrum of the Earth's atmosphere -- Seeing
Earth as an exoplanet using a lunar eclipse

[https://arxiv.org/abs/1405.4780](https://arxiv.org/abs/1405.4780)

~~~
smaili
Just out of curiosity, what's the reason for looking so far out? Are we
assuming by the time we would actually need to visit these planets, we've
discovered some method to go faster than the speed of light? I only ask
because _realistically_ , how do we expect to actually make use of these
resources if it would take so long just to reach it?

~~~
TangoTrotFox
The speed of light is not a speed limit on effective travel, but on
observation. Imagine you build an engine that gives enough thrust to roughly
produce an extra effective 1km/s of velocity each time you operate it. Even
though the speed of light is 300km/s, that engine is going to operate exactly
the same on the 301st operation as it did on the first operation. And, in
fact, in 'real' terms if we create an engine capable of generating 1g of
thrust for years at a time - we could travel 700 light years in ~12 years by
thrusting for 1g forward 6 years, turning around and then thrusting for 6
years backwards.

But of course the 'catch' is that time dilation (and length contraction) kick
in. And so while from the frame of reference of the ship and all its travelers
only 12 years will have passed, from the frame of reference of everybody back
on Earth - 700 years would have passed. What we would _observe_ is that as the
ship approached the speed of light, its apparent mass would approach infinity,
reaching a velocity asymptote at the speed of light.

And these values are also not linear. It's possible to travel a practically
unlimited distance in the span of a single human lifetime - from the
perspective of that human. 100 trillion light years would take about 62 years
at 1g from the perspective of those on board our ship. There's also really
really fun paradoxes available here. Imagine somebody leaves Earth towards
this planet and at some point decades, or perhaps even centuries later, we
develop technology that enables substantially faster travel. Our planetary
settlers on their 12 year journey could arrive 12 years later to find that not
only is the planet indeed colonized, but it's colonized by the descendents of
Earthlings that left decades, or even centuries, after they did.

The really exciting thing here is that NASA seems to have gone silent on the
EM drive after having it pass every single test they threw at it. In my
opinion, this is evidence of classification which is something that would make
sense. If the EM drive somehow actually works - and everything we know says it
most certainly should not - that would change absolutely everything. The
ability to actually start realistically considering these sort of missions
would be mundane compared to other possibilities, which I'm not even going to
get into as they sound, and should be, absurd. As an aside, this part on the
EM drive is 100% speculation - not to be confused with everything stated
above, which are direct and heavily tested (even if absurd sounding)
consequences of relativity.

~~~
tachyoff
> The speed of light is not a speed limit on effective travel, but on
> observation.

It is absolutely a limit on effective travel (if we ignore things like
wormholes for a second). Conventional motion through space is bounded by _c_
for several reasons, not the least of which being that the closer you get to
_c_ , the more energy it takes to make smaller and smaller changes in velocity
(the object acts as though it's gaining mass the faster it goes). In fact,
it's asymptotic. Accelerating a particle to _c_ would require an infinite
amount of energy.

~~~
TangoTrotFox
This is a common misunderstanding, and was the point of the example. A
stationary observer _observing_ a particle being accelerated towards the speed
of light would _observe_ that particles apparent mass begin to approach
infinity as its observed velocity approached the speed of light, thus
requiring an amount of energy approaching infinity to continue to accelerate
it further. However, this has nothing to do with the scenario with you being
that particle.

You are currently moving at near the speed of light relative to many things at
this very moment, yet your mass is certainly not approaching infinity, America
notwithstanding! And if you accelerated enough in the opposite direction of
your relative partner to exceed the speed of light it's not like you'd
suddenly start finding it impossible. No, it's a matter of observation. From
the other particle's perspective it would see your mass approaching infinity
and your speed would slow, but the distances you covered would remain the same
due to length contraction.

A similar effect explains why, for instance, particles in CERN's reactors
travel distances that should be impossible for them to travel before decaying.
E.g. if the speed of light was 10m/s and a particle decays after 3 seconds
then it should be impossible to see that particle travel more than 30 meters.
Yet we see it travel hundreds of meters. Isn't relativity fun?

~~~
tachyoff
Under relativity, you can't simply add speeds like that, unfortunately (I
believe this is related to the fact that the speed of light is the same in all
reference frames). Here's a link that can explain it better, though:
[http://curious.astro.cornell.edu/about-us/139-physics/the-
th...](http://curious.astro.cornell.edu/about-us/139-physics/the-theory-of-
relativity/special-relativity/1016-why-can-t-relative-velocities-add-up-to-
more-than-the-speed-of-light-intermediate)

In short, you can't go faster than light in any reference frame, relative to
any other observer.

Here's another source:
[https://physics.stackexchange.com/questions/75501/lorentz-
an...](https://physics.stackexchange.com/questions/75501/lorentz-and-galilean-
transformation)

~~~
TangoTrotFox
Absolutely. You are not understanding what you are reading. Let's
differentiate between 'mover' and 'observer' for clarity. In reality they're
completely interchangeable as being at rest relative to something moving 10m/s
is the same as you moving 10m/s if we consider the other particle to be at
rest.

As you accelerate more and more you will never observe yourself or anything
else exceeding the speed of light. Instead what will happen is that time will
begin to slow down and distances will begin to contract. If in our frame of
reference a distance is 100 meters, it would begin to seem to be, for
instance, 10 meters.

And the people observing you will also never see you exceed the speed of
light. Instead they will see you approach it, and then start to level off
asymptotically. Both views are correct. Time itself is what changes. From the
perspective of the observer, time will be moving more slowly for the observed.
e.g. this is why particles at CERN travel vastly greater distances than they
'should' be able to before decaying. Imagine what it would be like to
experience that travel from the particle's perspective.

This is why we see our particle last much longer than it should. And if humans
could live for 1500 years, this is why we would see things like our ship make
it's 700 light year journey, and then beam back a message that would only hit
us 1400 years later - telling us that they're safe and sound and got there in
12 years. Quite fun stuff!

Put another way, this would be the timeline of our ship in years from its
perspective and from earth's perspective:

    
    
        0 earth relative = ship leaves
        0 ship relative = ship leaves
    
        700 earth relative = ship arrives at planet
        12 ship relative = ship arrives at planet
    
        1400 earth relative = message from ship on planet arrives at earth
        712 ship relative = message from ship on planet arrives at earth
    

One final clarification, which might be unclear from the above. The ship
obviously does not magically warp through time or anything like that. If there
was a clock on the planet that started at T=0 when that ship left Earth, it
would read T=700 years when that ship arrived since that planet is itself also
roughly at rest relative to the ship.

This is the most counter intuitive thing about relativity, and time dilation.
It's not some 'trick' or matter of perspective. Time itself does literally
move at different rates for different people in different scenarios, even when
we're all in the same universe. Our ship pilot could make the 12 year journey
back and indeed 1400 Earth years would have passed in the interim, and if was
somehow able to measure the age of the other planet - 1400 years would have
also passed there as well. Even though he himself had only aged 24 years.

Should we achieve the ability to reach relativistic rates of travel - some
people may get their wish. Expect huge chunks of the rich to up and leave 'to
the future' (from our perspective we'd just see them constantly zipping around
near the speed of light... for centuries) in hopes of discovering if humanity
has overcome mortality by then! Reality is much stranger than fiction.

~~~
saagarjha
Sure, that’s all true, but you still haven’t shown that anything can go faster
than the speed of light. Time dilation and length contraction conspire to
cheat you from doing this.

~~~
lodi
Did you read what TangoTrotFox wrote? At no point did he invoke any faster-
than-light travel. He's just saying that by traveling at relativistic speeds
(e.g. 0.99c <= v < 1c), time dilation / length contraction work in your favor.
You can travel to systems thousands of light years away from Earth in only a
few years (as perceived by you, on your spaceship), all while traveling a bit
slower than light itself. Everyone left on Earth will still perceive you
taking >1000 years to arrive.

~~~
tachyoff
Except TangoTrotFox's original statement was:

> The speed of light is not a speed limit on effective travel, but on
> observation.

Which is absolutely factually false.

~~~
TangoTrotFox
No, it's correct - but speaking of physics on pop forums is pointless, because
of the Dunning Kruger effect.

There tend to be three groups of people:

\- Those that accept things at face value, which is quite silly. What I'm
saying should challenge all intuitive notions of reality making open
acceptance simply bizarre.

\- Those that reject things at face value. No better than the first and
generally driven by an extremely superficial understanding of physics. As
Feynman phrased it, people sipping martinis at a cocktail party and discussing
relativity, "Ah yes.. how insightful. Though I think some things may indeed be
inherently correct. Mmm..."

\- And those with a strong physics background already, to whom you provide no
additional value to anyhow.

------
nategri
Image backgrounds on plots: Just say no, kids.

------
tr4cefl0w
It takes 148.75 days to reach WASP-39b at Warp factor 9. Not bad.

------
blackrock
I wanted to talk about artificial gravity.

Since we're speaking of planets light years away. The only way for humans to
get out there, is to stay in some kind of spaceship with gravity.

Floating around on the International Space Station is nice for an hour. But
after that, I bet it gets boring real quick. Especially, if you need to go use
the restroom, and handle liquids and solids.

So, having artificial gravity is nice. It will keep liquids down. You can
drink out of a cup. Food doesn't float away. You can surgically operate
safely. You can use the restroom normally.

But, you would need a very large structure, to spin around, in order to not
get the effects of Coriolis Force. And since it is currently difficult to
build such a large structure in space, then I wondered if we could cheat.

The method is to apply a constant force, but at an angle. This angle will
allow the space craft to simulate a rotation, like it is being spun around
with an invisible tether. This angular force will push all the occupants
inside, to feel 1 G of gravity. And after one full rotation, then the space
craft will return to the origin point.

So, the idea is to apply an angular force, to cause a space craft to rotate in
place, to simulate artificial gravity.

This is similar to the idea of constantly accelerating a spacecraft, so that
the occupants feel 1 G of gravity. But that acceleration would shoot the
occupants straight into deep space, which is not what we want.

Instead, this method would be like simulating a Ring World, but instead of
rotating the space station, it would use constant angular force to cause the
rotation, in order to simulate the artificial gravity.

I was thinking something like an electric-ion engine could be used to provide
the constant thrust. It would need to be computer controlled, to automatically
administer the right force, at the correct angle, at the correct time, in
order to rotate and simulate the artificial gravity. And it can be powered by
nuclear, or possible solar. And of course, the thrust can never be turned off,
otherwise, the space craft would shoot off into deep space.

One idea I thought was to have this be in a large orbit around the earth. The
other location would be at the Earth-Moon Lagrangian Point.

Any space infrastructure architects want to take a stab at this idea? Possible
or not?

~~~
Mayzie
You should watch The Expanse, a very good TV show.

Their ships accelerate at a comfortable level to generate gravity for half of
the destination, and then "flip-and-burn" by accelerating in the opposite
direction at the same comfortable level to generate gravity.

~~~
akvadrako
That only works inside the solar system. The energy requirements to accelerate
for a year are enormous. With 100% efficient engines, you would need something
like a reaction mass the size of Jupiter.

On the plus side you quickly approach _c_. At constant 1g acceleration /
deceleration, Andromeda is about 28 years away.

~~~
crowbahr
I'm assuming you mean subjective time right?

Because you can't cover 2.578 million light years in only 28 years moving at c
from the reference frame of Earth.

~~~
lodi
Right, the people onboard the spaceship will only perceive 28y to have gone
by. People on Earth will perceive the spaceship accelerating away for millions
of years.

------
samstave
Probes:

What is max velocity we can, with current tech, achieve for shooting a probe
to a target;

Possible to build a giant rail gun in space where a falcon heavy is the
payload (plus a nuke battery) and we shoot the falcon heavy out the rail gun,
then at some point it’s various components engage to keep it heading to
target.

Also if you shoot a rocket out a rail gun, and it’s clipping along, will the
rocket thrust add any velocity, or should you save all that fuel to land the
heavy on the remote planet?

Do rail guns behave differently in space?

~~~
coinerone
The position of the Planet will not be the same when the "Projectile" will
arrive. The Railgun must aim to the Destination the Planet will be. Fault
tolerance will be a bigger issue than building a giant Railgun (Walmart maybe
has one in stock already :P).

------
perseusprime11
It will be cool to spot dinosaurs on these exoplanets. Whatever made it
possible to create these giant creatures should be on atleast few exoplanets.

------
hguhghuff
Will the day ever come when astronomy is commemted on without "the likelihood
of life" being attached to it?

------
zabana
I dream of the day NASA makes Cowboy Bebop a reality.

------
KasianFranks
700 light years away. We'll need to solve for human lifespan first. There's
another planet about 5 light years away. It's just a matter of time.

~~~
Asooka
If you build a ship that accelerates at a constant 1g towards the destination
until the midway point, then decelerates at a constant 1g, due to time
dilation, the people on board would experience "only" 12 years passing for a
700LY journey. People on Earth would still need to wait 1400 years for the
first communication back, of course, but at least you won't have to build
generation ships.

Edit: I got my numbers from
[http://convertalot.com/relativistic_star_ship_calculator.htm...](http://convertalot.com/relativistic_star_ship_calculator.html)

~~~
tpaschalis
The thing is, we aren't currently able to keep a stable acceleration of 1g.

The ship's mass will also increase relativistic-ally, as it will reach a
maximum speed of ~0.9999961c, so more mass will require more force for the
same acceleration.

~~~
bmcooley
Wouldn't the ship's mass only appear to increase to the outside observer?

------
IntronExon
Is there any way the link could be changed to the original?
[https://www.nasa.gov/feature/goddard/2018/nasa-finds-a-
large...](https://www.nasa.gov/feature/goddard/2018/nasa-finds-a-large-amount-
of-water-in-an-exoplanets-atmosphere)

NASA > Phys.org

~~~
dang
Sure. URL changed from [https://phys.org/news/2018-03-nasa-large-amount-
exoplanet-at...](https://phys.org/news/2018-03-nasa-large-amount-exoplanet-
atmosphere.html).

~~~
superkuh
This is actually a step backwards in accessibility. The phys.org article could
be read with any browser, text to speech, or sight assistance tools.

But the NASA.gov page is just a blank, black screen until you turn on
javascript and it renders the text in.

------
davidw
Planet Oregon.

------
aerodog
I wish our government spent all that money figuring out how to make seawater
affordably drinkable. Interesting nonetheless.

~~~
_emacsomancer_
You could have also devoted some time to that problem instead posting a
comment on Hackernews.

~~~
aerodog
haha touché! but i am but one man

~~~
_emacsomancer_
That's true. Get a few more people together and you could have a real HN
commenting team.

