
NASA plans to launch a spacecraft to Titan - the-enemy
https://www.theatlantic.com/science/archive/2019/06/titan-saturn-nasa-dragonfly/592882/
======
rzimmerman
A flying drone is a really solid idea for a Titan lander for a couple reasons:

* The surface atmosphere density is higher than Earth's (1.5 atm)

* Gravitational force is much lower (0.15g)

* We don't know a lot about the surface composition or topography, so wheels and motors represent a challenge

* Visibility may be poor, making visual navigation tricky (though that's also a problem for a flying vehicle I suppose)

I've heard people ask about "why a nuclear power source?" Saturn is 10x as far
from the sun as Earth, so sunlight is about 1/100th as bright. In addition,
Titan's atmosphere blocks most of that. There really isn't any other realistic
option.

I hope it works and they take videos.

~~~
cwkoss
In addition to lack of solar energy, I wonder if nuclear power source is
necessary to keep batteries or other electronics warm enough to function
properly.

Conversely, on Titan, we won't need to worry about heat sinks as everything is
kept at ~94K in a bath of liquid and frozen methane. Perhaps in a few hundred
years AWS's most popular region for intensive compute will be under Titan's
methane sea. High spin up cost, but cheap super-conduction environment once
you're up.

~~~
ajmurmann
Hah, I was always intrigued by the idea of placing solar cells on the bright
side of Mercury and servers on the dark side. I wonder what other good options
might exist in the solar system.

~~~
AnIdiotOnTheNet
Mercury's whisper thin atmosphere won't be much use for cooling anything,
though possibly the surface would be. However, the real problem is that
Mercury isn't actually tidally locked anyway.

~~~
MereInterest
You could have the facility move constantly to keep the facility straddled
across the sunlight line. At the equator, this would require constantly moving
at about 7 mph, though you could reduce the speed necessary by moving to
higher latitudes.

~~~
akozak
Appears in 2312 by Kim Stanley Robinson.

~~~
joshgel
They move the whole city around the planet at 7mph!! 10/10 would recommend

~~~
taneq
Sounds like Absolution Gap and/or a less annoying version of the Mortal
Engines movie (please tell me the book was better than this).

------
apo
> Scientists suspect that Titan might even have water—real, actual H2O—lurking
> beneath its surface.

Not just a little, but a lot of water:

> The density of Titan is consistent with a body that is about 60% rock and
> 40% water.

> ...

> Pre-Cassini models of impact trajectories and angles suggest that where the
> impactor strikes the water ice crust, a small amount of ejecta remains as
> liquid water within the crater. It may persist as liquid for centuries or
> longer, sufficient for "the synthesis of simple precursor molecules to the
> origin of life".[107]

[https://en.wikipedia.org/wiki/Titan_(moon)](https://en.wikipedia.org/wiki/Titan_\(moon\))

~~~
dmurray
> The density of Titan is consistent with a body that is about 60% rock and
> 40% water.

That's extremely misleading.

First, rocks have different densities. Sandstone weighs 2g/cc, basalt weighs
3g/cc, so a density "consistent with" 50% basalt, 50% water would be equally
consistent with 100% sandstone, not to mention the possibilities of rocks with
drastically different densities such as pumice or iron.

Secondly, we are pretty certain Titan has large quantities of liquid methane
and/or ethane (check the same Wikipedia link) which certainly account for some
of the difference in density between Titan and other rocky bodies.

So yes, there is water on Titan, but it's about as likely to be 40% water as
it is to be 40% cheese or 40% iPhones, even if its density suggests a makeup
consistent with that.

~~~
apo
> That's extremely misleading.

You're right - I should have said: " _potentially_ a lot of water."

Sandstone (silicon oxides) seems unlikely given the reducing nature of the
atmosphere. I'm no expert, but when liquid hydrocarbons rain down, there's not
a lot of free oxygen on the surface at least. Ditto for basalt, which is about
40-50% silicon oxide. Still there could have been some process by which the
interior sequestered most of the planet's oxygen, leaving what remained on the
surface as water.

In contrast, liquid hydrocarbons seem plausible given the stuff rains down
from the atmosphere and its density (methane ~0.5 g/mL, -162 C).

Titan's orbit provides some evidence consistent with a body that's more dense
at the surface than at the core. One explanation is large amounts of
subsurface liquid, but there are others:

[https://www.popsci.com/science/article/2011-04/titan-
could-h...](https://www.popsci.com/science/article/2011-04/titan-could-harbor-
massive-ocean-beneath-its-methane-lakes-study-says/)

There's been some discussion about the apparent massive block of ice in
Titan's surface, so the idea that Titan's putative subsurface ocean could
contain water isn't too wild a speculation:

[https://www.space.com/titan-saturn-moon-weird-ice-
formation....](https://www.space.com/titan-saturn-moon-weird-ice-
formation.html)

A subsurface ocean composed of water and liquid hydrocarbons would be
consistent with everything I've been able to find so far.

------
tectonic
Dragonfly is a super exciting mission. Between it and the other New Frontiers
finalist, CAESAR, it makes sense that Dragonfly would win because the ESA just
announced their own comet exploration mission (the Comet Interceptor, which is
3 spacecraft that will loiter together at L2 until an interesting comet or
Oumuamua-like interstellar object wanders into the inner solar system).

Anyway, Dragonfly: RTG-powered quadcopter to fly around Titan's low gravity
and dense atmosphere. Over its 2.5-year primary mission, Dragonfly should
cover ~180 kilometers of territory.

Self-promotion: If you're into space exploration, check out our weekly space
industry newsletter called The Orbital Index
([https://orbitalindex.com](https://orbitalindex.com)). We're going to cover
this in depth in next week's issue.

~~~
andygates
That's a _huge_ range!

------
maxxxxx
I love this mission. From a science point of view it’s probably good to send
similar and well tested rovers to Mars. But to me it gets boring.

I think NASA used to get a lot of fascination from doing the seemingly
impossible like flying to the moon. So I think a mission like this will be
fascinating for a lot of people. Also it may spawn off a lot of technology. I
hope for a submarine mission to Europa.

~~~
Robotbeat
I think a flying mission is actually superior to a rover as it can cover far
more ground and reach some sites that wouldn't be feasible for a rover. And
Titan is uniquely suited to using flight to explore as its gravity is a factor
7.25 lower and its atmosphere a factor of 4.4x denser. That means it's about
30 times easier to hover and covering the same distance is at least 7 times as
efficient as on Earth, besides having lower terminal velocity.

Even this relatively "inefficient" quadcopter (8 rotor) design could cover
dozens of miles (~60km, more than any Mars rover has ever done in its entire
mission) in a single hop (which could be recharged by the MMRTG in a single
week-long night), although prudence suggests shorter hops at first. That means
in principle over its ~10 year lifespan (assuming it can last as long as
Cassini did...) it could nearly circumnavigate the entire planet (diameter of
~5000km, day period of about 16 Earth days) while visiting dozens of sites.
Granted, range will likely be much more modest as the mission operators will
be focusing on not losing this valuable asset, but it shows just how powerful
the ability to fly could be. It can visit more sites than all the surface
robotic missions to Mars combined. In that sense, it's a _fantastic_
scientific value. And I think the public will absolutely love it.

Information from the Dragonfly proposal document:
[http://dragonfly.jhuapl.edu/News-and-
Resources/docs/34_03-Lo...](http://dragonfly.jhuapl.edu/News-and-
Resources/docs/34_03-Lorenz.pdf)

~~~
cheerlessbog
> over its ~10 year lifespan (assuming it can last as long as Cassini did...)

Cassini wasnt exposed to solvents, rocks and didn't have moving parts (at
least not to keep it aloft). Have they made a public statement about lifespan?

~~~
Robotbeat
Yes, the planned mission time is 2.7 years. MMRTG should provide sufficient
power for at least 8 years.

------
hughes
It's interesting that there is no existing (or planned) launch vehicle that
could perform a direct injection for this mission. Getting to Saturn is
really, really hard, and without multiple gravity assists from the inner solar
system it would be simply impossible.

Too bad it results in an 11 year transit time though! Flying direct would save
almost 8 years of that...

~~~
pier25
> _Getting to Saturn is really, really hard_

Why is that?

~~~
hughes
Just the speeds required. This mission will effectively have a speed of about
17km/s _faster_ than the speeds just to get to low Earth orbit after its final
gravity assist.

------
codezero
This is great news. When Huygens landed on Titan, the images sparked my
interest in physics and planetary science, and eventually I went on to do
research in solar physics.

------
mzs
NASA's PR: [https://www.nasa.gov/press-release/nasas-dragonfly-will-
fly-...](https://www.nasa.gov/press-release/nasas-dragonfly-will-fly-around-
titan-looking-for-origins-signs-of-life/)

NASA's announcement video:
[https://youtu.be/xn3-0a19sC8](https://youtu.be/xn3-0a19sC8)

------
keiferski
_What’s Titan look like this time of year?_

[https://youtube.com/watch?v=lZa83dTf4JA](https://youtube.com/watch?v=lZa83dTf4JA)

Exciting to see reality (almost) following fiction. Gattaca is an excellent
film, if you haven’t seen it.

------
sidcool
Mad props to the scientists and engineers making something like this possible.
In an alternate life I would choose to be an astrophysicist or rocket
engineer. Hopefully I will be more intelligent in the next life.

------
gattr
Associated read: "Titan" by Stephen Baxter. Hard SF describing a manned
mission to Titan using present-day level tech; great attention to detail, but
be warned that the overall tone is rather depressing.

Myself, I'm absolutely fascinated by the confirmed hydrocarbon lakes and
rivers on Titan and can't wait to see actual optical images from up close (so
far we only got synthetic-aperture radar images [0]).

[0]
[https://en.wikipedia.org/wiki/Titan_(moon)#Lakes](https://en.wikipedia.org/wiki/Titan_\(moon\)#Lakes)

------
dsfyu404ed
I can't believe it's been that long since Huygens was sent to Titan. I
remember listening to some radio show (NPR?) that was broadcasting the
touchdown live.

Also, it's interesting that since they can't study Titan very well visually
(you can't point a telescope at it and map the surface like you can with Mars)
they're planning on sending a rover that can cover far more distance since
they have less idea what will be "interesting" beforehand.

~~~
UncleSlacky
I worked on prototypes of the experiments in the Surface Science Package at
uni in 1991 - boy do I feel old!

Even then we were speculating on flying or floating probes for future missions
there. At the time it was assumed that the surface could well be entirely
liquid.

------
blach
I'm interested to see how this mission is couched from a PR standpoint
(specifically the long long transit time). Emily Lakdawalla from the planetary
society had a good tweet related to this:
[https://twitter.com/elakdawalla/status/1144492247032799238?s...](https://twitter.com/elakdawalla/status/1144492247032799238?s=20)

------
LyalinDotCom
I also found a really good write-up of the mission here:
[http://www.4erevolution.com/en/dragonfly-un-drone-a-
propulsi...](http://www.4erevolution.com/en/dragonfly-un-drone-a-propulsion-
nucleaire-pour-explorer-titan/amp/)

------
rolltiide
It is nice that multiple public sector agencies worldwide are doing space
travel now, with the private sector close behind.

Relying solely on NASA and the political funding machinations of the White
House and Congress would put our understanding of the planets very far behind.

~~~
jvanderbot
I'm confused by your comment. this is absolutely a NASA mission, subject to
all the whims of congress that any other is.

APL has long bid on missions and instrument proposals just like other
institutions.

~~~
rolltiide
Its just a statement of fact.

NASA likely wouldnt even have revisited this moon without the European probe
taking pictures under the atmosphere

It is nice that multiple public sector agencies worldwide are doing space
travel now

~~~
jvanderbot
Ah, I see. I agree, worldwide collaboration and competition is very healthy
for a space program.

------
vorticalbox
>To protect the hazy moon, engineers deliberately shoved Cassini into Saturn,
a gaseous planet incapable of hosting life.

Can we be 100% sure there isn't life.

~~~
unchocked
We can be sure that Earthling life wouldn't survive in Saturn, thus posing no
threat to hypothetical Saturnian biology.

~~~
aeorgnoieang
_Almost all_ Earth life sure, but I wouldn't bet on absolutely none being able
to survive. NASA can't even completely sterilize their vehicles and payloads
already.

------
rhacker
They are planning to send it up in 2026? What are they going to be doing for
6+ years?

~~~
asteli
They just announced it today. They don't have a probe yet. They have to design
and build and test all of the equipment and systems that are going to go into
space. I think it's pretty reasonable for this to take 6 years.

------
LordLotherak
NASA is really good at planning future missions. Implementing them? I've heard
hundreds of fantastical half-baked ideas and very few of them materialize over
the course of my 46 years on earth.

~~~
Sharlin
Eh, almost every NASA robotic mission that has gotten this far in the design
and selection process has also flown. They're way past the "fantastical half-
baked idea" stage. The financial reality is that NASA can only finance one or
two billion-dollar missions per decade, and the competition is rather fierce.
To be selected as _the_ New Frontiers class mission of the late 2020s is a big
deal, and you can be sure that at this point the proposing team has made a
very solid case for their mission.

~~~
Robotbeat
Yup. The robotic program has a very good track record of successes, even for
crazy stuff like the Mars Science Laboratory’s sky crane descent stage:
[https://m.youtube.com/watch?v=Ki_Af_o9Q9s](https://m.youtube.com/watch?v=Ki_Af_o9Q9s)

It’s the human spaceflight program that has had the, um, difficulties. There
are signs of hope, though.

------
droithomme
Venus and Titan have in common that probes landing there tend to only operate
a few minutes before failing due to the extreme conditions.

A helicopter sounds great, but perhaps it would make sense to try to simply
make a probe that can stay alive there long enough to do anything other than
send a couple pictures back.

~~~
Robotbeat
This is not true. The only reason the previous probe (Huygens) only lasted a
few hours is because it was battery powered (and the battery wasn't
particularly large). This probe will carry a power source powered by the
radioactive decay of Plutonium 238 (virtually all the radiation being alpha
particles, which are easily blocked by the casing of the power supply and thus
will not hurt the electronics or ground crew) that can provide 50-100 Watts of
power for years or even decades.

~~~
UncleSlacky
As I mentioned elsewhere in this thread, before Huygens we expected that the
surface might well be entirely liquid, giving us at best only a few minutes to
run the experiments and return the data before it sank. There was no point
carrying too much battery capacity in that case.

~~~
Robotbeat
No. Huygens was designed to float and last hours. The battery capacity is why
it lasted so short.

------
mattfrommars
I'll be 43 when this craft arrives there. Damn.

~~~
zhoujianfu
I’ll be 43 in March. Damn.

------
plutonorm
What. How are they going to detect life on titan? They can't even detect life
on mars. I mean to say, even when we know the kind of life we are looking for
we get confused about how to confirm or deny its existence. So they want to
design a small flying drone that works in extremely hostile conditions, that
also has the kinds of sophisticated instruments needed to look for life? And
not just life, life of potentially a completely unknown form, given the widely
different surface conditions. This just seems like a weird mission. Finish up
the Viking labelled release experiments on mars first, then go take a look in
the mid Venusian atmosphere. Then take a gander at europa.... Weird mission

~~~
calcifer
> Finish up the Viking labelled release experiments on mars first, then go
> take a look in the mid Venusian atmosphere. Then take a gander at europa

This is exactly why I like HN. Here, you have the true experts contributing
valuable science with their credentials laid bare, as opposed to the pencil
pushers at NASA who probably only approved this mission because it sounded
cool.

