HN Gopher Feed (2017-09-25) - page 1 of 10
NASA Designed a Low-Tech Rover to Survive Venus
83 points by sprucelyhttps://www.wired.com/story/nasa-low-tech-rover/
curtis - 3 hours ago
I find the idea of an essentially clockwork rover really
interesting but from a practical standpoint I still think the ideal
rover for Venus would be like a cross between an submersible and an
airship.When the rover starts to run out of coolant it would
inflate the airbag, rise up to about the one atmosphere level
(50km?), use solar power to replace the coolant, then descend again
for another ground mission. And since the venusian atmosphere is
about 5% nitrogen, nitrogen seems like the ideal coolant, and, on
top of that, it's probably the ideal lift gas for Venus as well.
This is because pure gaseous nitrogen is considerably less dense
than gaseous carbon dioxide.
methodover - 1 hours ago
I wonder if we should be exploring the atmosphere of Venus
instead anyway. My understanding is the best chance of life is in
the upper atmosphere anyway.
jychang - 1 hours ago
Uhh, an airship? On a planet with winds at 350kmph?That sounds
like a horrible idea.
azernik - 1 hours ago
They'll move you along, but as long as there's little
turbulence or wind shear, it won't damage anything. And given
that the wind moves in a consistent direction and speed varies
mostly just with altitude, I doubt there's much of either.
elihu - 12 minutes ago
According to wikipedia, winds are pretty slow near the surface.
Strong winds at high altitudes might be a problem if there's
turbulence, but if there isn't it's probably okay.> Thermal
inertia and the transfer of heat by winds in the lower
atmosphere mean that the temperature of Venus's surface does
not vary significantly between the night and day sides, despite
Venus's extremely slow rotation. Winds at the surface are slow,
moving at a few kilometres per hour, but because of the high
density of the atmosphere at the surface, they exert a
significant amount of force against obstructions, and transport
dust and small stones across the surface. This alone would make
it difficult for a human to walk through, even if the heat,
pressure, and lack of oxygen were not a problem....> The only
appreciable variation in temperature occurs with altitude. The
highest point on Venus, Maxwell Montes, is therefore the
coolest point on Venus, with a temperature of about 655 K (380
?C; 715 ?F) and an atmospheric pressure of about 4.5 MPa (45
bar)....> Strong 300 km/h (185 mph) winds at the cloud tops go
around Venus about every four to five Earth days.https://en.wik
ipedia.org/wiki/Venus#Atmosphere_and_climateGiven the thickness
of the atmosphere, maybe the most sensible form of locomotion
on the surface is to just let the wind carry you along...
KGIII - 59 minutes ago
They aren't the first to propose it, though I haven't seen
anyone suggest it go to the surface.NASA's proposal:https://en.
m.wikipedia.org/wiki/High_Altitude_Venus_Operatio...I am fond
of the name HAVOC.
ChuckMcM - 4 hours ago
Who knew steam punk would come in handy :-) Seriously though it is
an excellent thought experiment to design a purely mechanical
rover. The concept of using a windmill to wind a spring is pretty
neat, although at 850 degrees its going to be a challenge to find a
dsfyu404ed - 3 hours ago
>although at 850 degrees its going to be a challenge to find a
spring material.Google "Exhaust heat riser"A spring that
provides many years of useful service when exposed to high
temperatures isn't a very exotic part. NASA probably isn't
trying to make it go 5yr/50,000mi without failing so they can
probably come up with something that works well for the duration
of the mission.
ChuckMcM - 2 hours ago
Although most heat risers seem to simply be a bi-metal allow
which changes shape when hot. The article discusses winding
springs much like a clock maker would use.That said, a bit of
searching did find Iconel 718 springs which are good up to 1000
degrees. Not a lot of margin but probably workable. Since
people has developed techniques for 3D printing Iconel 718 it
seems like that problem at least is workable.
shookness - 1 hours ago
I used to do research in a lab which studied extreme temperature
electronics using Silicon Carbide CMOS. These electronics are able
to handle over 450 C ambient temperatures and may be able to
survive in the Venusian atmosphere with minimal shielding. Looks
like they started a company and have funding for jet engine
dzdt - 2 hours ago
See this page on extreme temperature electronics for a good
discussion of what is available on the electronics side. The short
answer is, there are discrete components that have been
demonstrated to temperatures higher than Venus's 460C but little
commercially available. In particular no integrated circuits.
criddell - 3 hours ago
Did ancient Earth have a more Venus-like atmosphere? If not, what's
responsible for the difference? Is it due to the extra solar energy
that Venus receives?
brianberns - 3 hours ago
Runaway greenhouse effect due to high levels of atmospheric CO2.
criddell - 3 hours ago
Does that also explain the corrosive nature of the atmosphere?
mturmon - 1 hours ago
Short story is that the well-known sulfuric acid clouds are
produced by plentiful CO2 combining in the atmosphere with
trace SO2 and H2O gases. The high temperatures prevent the
CO2 and SO2 from being captured into minerals, as they are on
phkahler - 3 hours ago
This caused me to search for very high temperature semiconductors.
It turns out there are some rated for 300 to 400C operation. This
mission seems to require 450C+ but that's close. This seems like
another area where RISC-V would be very beneficial, as the
companies that make very high temperature chips could benefit
greatly from an open instruction set with simple free designs. One
company had 8051s rated over 200C, but that arch is a bit dated.
ars - 3 hours ago
I wonder if it would be easier to find discrete components that
work at high temperature. And use a vacuum tube instead of a
transistor - vacuum tubes can handle high temperature easily.Put
all of them in a single strong container instead of using lots of
fragile glass in a high pressure environment. And you won't need
to heat the emitter, saving weight.
libria - 2 hours ago
To hell with it. Let's just ship it with a miniature Babbage
engine and finally give it the practical application it
mozumder - 1 hours ago
Don't forget you're also adding heat from operations in addition
to ambient temperature. I can easily see junction temperatures
reach 500+ C.
WillReplyfFood - 4 hours ago
Why not make the robot a worm, that drills beneath the ground after
arriving in a impactor?All the samples you need, with only a part
of the pressure and none of the toxic atmosphere?I know it would
not make scenic photos- and take forever to get anywhere- but it
rtkwe - 7 minutes ago
Burrowing through anything other than loosely packed soil by
necessity creates a larger volume of tailings than the original
rock which has to be constantly cleared to the surface. Packing a
useful science lab into a robot small enough to burrow through
loose top soil on Venus (which may or may not be very deep or
even really exist since we know very little about the surface of
Venus) would be difficult to impossible. Second in the case of
going through hard rock via drilling, the drill teeth have a
limited life span and would be extremely difficult to replace in
an automated way.
masklinn - 3 hours ago
Digging machines are quite complex and prone to failure (that is
one area where humanity is basically nowhere compared to
biologicals), you'd have trouble exfiltering the information, and
packing the analysis ware would be even more difficult than in a
mturmon - 4 hours ago
Press release with a bit more on the
venusThe WIRED article has errors. They got the PI's name wrong.
They also say this about communications:"the Venus rover will use a
simple optical reflector to transmit its data to orbiting
satellites by flashing radar light like morse code"This is
misleading in a couple of ways. The rover in the link above
appears to use radar targets which turn on wheels; an orbiter would
bounce radio off the target to determine their configuration.
yincrash - 11 minutes ago
A better analogy might be that it's akin to signal flags.
skykooler - 2 hours ago
> Those treads are powered via a wind turbine that captures the
planet?s whipping wind gustsThis seems odd to me - Venus has high
wind speeds in the upper atmosphere, but on the surface the winds
are only one or two m/s. Is that enough to wind a spring?
milesokeefe - 1 hours ago
With sufficient gear reduction any wind at all is enough to wind
a spring, albeit slowly.
bad_alloc - 1 hours ago
Wikipedia says:> Savonius turbines are used whenever cost or
reliability is much more important than efficiency.The German
article is a bit more detailed and claims that Savonius tubines
are effective at speeds as low as 2m/s and produce high torque
even then. Maybe the high pressure on Venus increases this
philipkglass - 1 hours ago
Yes, because atmospheric density at the surface of Venus is 67
kg/m^3m, about 55 times as dense as sea level atmosphere on
bad_alloc - 1 hours ago
This is a great example of space exploration that could produce
technology relevant for applications on Earth: If you have a
complex machine that can do usefuk work on Venus, you can use a
similar concept for ultra-durable equipment here. Stuff like this
could be relevant for deep sea exploration, nuclear applications,
mining and so on.
Animats - 2 minutes ago
Maybe it can rove around on wind power and gears, but if it can't
send pictures back, it's going to be a disappointment.
nradov - 2 hours ago
We previously discussed an IEEE Spectrum article on the same
api - 1 hours ago
I wonder if a vacuum tube computer could survive Venusian
temperatures if it was built out of the right materials?
crispyambulance - 3 hours ago
I thought one idea for Venus was to have a balloon with a gondola
that would float high in the atmosphere, that way it wouldn't have
to handle extreme temperature and it would just need to deal with
the occasional sulfuric acid thunderstorm!
kwoff - 2 hours ago
It's this kind of research into extremes that drives technology
forward. Let's explore Venus!