Explanation: Awkward and angular looking, Apollo 17's lunar module Challenger was designed for flight in the near vacuum of space. Digitally enhanced and reprocessed, this picture taken from Apollo 17's command module America shows Challenger's ascent stage in lunar orbit. Small reaction control thrusters are at the sides of the moonship with the bell of the ascent rocket engine underneath. The hatch allowing access to the lunar surface is seen at the front, with a round radar antenna at the top. Mission commander Gene Cernan is clearly visible through the triangular window. This spaceship performed gracefully, landing on the Moon and returning the Apollo astronauts to the orbiting command module in December of 1972. So where is Challenger now? Its descent stage remains at the Apollo 17 landing site in the Taurus-Littrow valley. The ascent stage pictured was intentionally crashed nearby after being jettisoned from the command module prior to the astronauts' return to planet Earth. Apollo 17's mission came to an end 47 years ago today. It was the sixth and last time astronauts landed on the Moon.
olman wrote: ↑Thu Dec 19, 2019 11:09 am
Incredibly flimsy looking thing - like the earliest airplanes, just fabric and wire.
Not as flimsy as it looks, but certainly, all of the fabric and foil insulation makes it look that way.
O Kapton! My Kapton! our fearful trip is done;
The ship has weather'd every rack, the prize we sought is won;
The port is near, the bells I hear, the people all exulting,
While follow eyes the steady keel, the vessel grim and daring:
But O heart! heart! heart!
O the bleeding drops of red,
Where on the deck my Kapton lies,
Fallen cold and dead.
<<The descent stage of the Apollo Lunar Module, and the bottom of the ascent stage surrounding the ascent engine, were covered in blankets of aluminized Kapton foil to provide thermal insulation. During the return journey from the Moon, Apollo 11 astronaut Neil Armstrong commented that during the launch of the Lunar Module ascent stage, he could see "Kapton and other parts on the LM staging scattering all around the area for great distances."
NASA's New Horizons spacecraft used Kapton in an innovative "Thermos bottle" insulation design to keep the craft operating between 10–30 °C. The main body is covered in lightweight, gold-colored, multilayered thermal insulation which holds in heat from operating electronics to keep the spacecraft warm. The thermal blanketing–18 layers of Dacron mesh cloth sandwiched between aluminized Mylar and Kapton film–also helped to protect the craft from micrometeorites.
The sunshield of the James Webb Space Telescope is also made of aluminized Kapton. The NASA Jet Propulsion Laboratory has considered Kapton as a good plastic support for solar sails because of its long duration in the space environment.
Kapton is a polyimide film developed by DuPont in the late 1960s that remains stable across a wide range of temperatures, from −269 to +400 °C.
The thermal conductivity of Kapton at temperatures from 0.5 to 5 kelvin is rather high for such low temperatures. This, together with its good dielectric qualities and its availability as thin sheets have made it a favorite material in cryogenics, as it provides electrical insulation at low thermal gradients. Kapton is regularly used as an insulator in ultra-high vacuum environments due to its low outgassing rate. [Unfortunately] according to a NASA internal report, space shuttle "wires were coated with an insulator known as Kapton that tended to break down over time, causing short circuits and, potentially, fires."
Kapton is also commonly used as a material for windows of all kinds at X-ray sources (synchrotron beam-lines and X-ray tubes) and X-ray detectors. Its high mechanical and thermal stability and high transmittance to X-rays make it the preferred material. It is also relatively insensitive to radiation damage.>>
O Kapton! My Kapton! our fearful trip is done;
The ship has weather'd every rack, the prize we sought is won;
The port is near, the bells I hear, the people all exulting,
While follow eyes the steady keel, the vessel grim and daring:
But O heart! heart! heart!
O the bleeding drops of red,
Where on the deck my Kapton lies,
Fallen cold and dead.
<<The descent stage of the Apollo Lunar Module, and the bottom of the ascent stage surrounding the ascent engine, were covered in blankets of aluminized Kapton foil to provide thermal insulation. During the return journey from the Moon, Apollo 11 astronaut Neil Armstrong commented that during the launch of the Lunar Module ascent stage, he could see "Kapton and other parts on the LM staging scattering all around the area for great distances."
NASA's New Horizons spacecraft used Kapton in an innovative "Thermos bottle" insulation design to keep the craft operating between 10–30 °C. The main body is covered in lightweight, gold-colored, multilayered thermal insulation which holds in heat from operating electronics to keep the spacecraft warm. The thermal blanketing–18 layers of Dacron mesh cloth sandwiched between aluminized Mylar and Kapton film–also helped to protect the craft from micrometeorites.
The sunshield of the James Webb Space Telescope is also made of aluminized Kapton. The NASA Jet Propulsion Laboratory has considered Kapton as a good plastic support for solar sails because of its long duration in the space environment.
Kapton is a polyimide film developed by DuPont in the late 1960s that remains stable across a wide range of temperatures, from −269 to +400 °C.
The thermal conductivity of Kapton at temperatures from 0.5 to 5 kelvin is rather high for such low temperatures. This, together with its good dielectric qualities and its availability as thin sheets have made it a favorite material in cryogenics, as it provides electrical insulation at low thermal gradients. Kapton is regularly used as an insulator in ultra-high vacuum environments due to its low outgassing rate. [Unfortunately] according to a NASA internal report, space shuttle "wires were coated with an insulator known as Kapton that tended to break down over time, causing short circuits and, potentially, fires."
Kapton is also commonly used as a material for windows of all kinds at X-ray sources (synchrotron beam-lines and X-ray tubes) and X-ray detectors. Its high mechanical and thermal stability and high transmittance to X-rays make it the preferred material. It is also relatively insensitive to radiation damage.>>
Art, sometimes I love you. Or at least your posts. This is one of those occasions. Oh Kapton, indeed!
Although it has been reprocessed it seems amazing to me the quality of this pic if we consider it was taken almost 50 years ago.
Great ship by the way.
In space, no one can hear you sing, but it can snow.
In astronomy or planetary science, the frost line, also known as the snow line or ice line, is the particular distance in the solar nebula from the central protostar where it is cold enough for volatile compounds such as water, ammonia, methane, carbon dioxide, carbon monoxide to condense into solid ice grains. Different volatiles have different condensation temperatures at different partial pressures (thus different densities) in the protostar nebula, so their respective frost lines will differ. The actual temperature and distance for the snow line of water ice depend on the physical model used to calculate it and on the theoretical solar nebula model:
170 K at 2.7 AU (Hayashi, 1981)[1]
143 K at 3.2 AU to 150 K at 3 AU (Podolak and Zucker, 2010)[2]
3.1 AU (Martin and Livio, 2012)[3]
≈150 K for μm-size grains and ≈200 K for km-size bodies (D'Angelo and Podolak, 2015)[4]
The radial position of the condensation/evaporation front varies over time, as the nebula evolves. Occasionally, the term snow line is also used to represent the present distance at which water ice can be stable (even under direct sunlight). This current snow line distance is different from the formation snow line distance during the formation of the Solar System, and approximately equals 5 AU.[5] The reason for the difference is that during the formation of the Solar System, the solar nebula was an opaque cloud where temperatures were lower close to the Sun,[citation needed] and the Sun itself was less energetic. After formation, the ice got buried by infalling dust and it has remained stable a few meters below the surface. If ice within 5 AU is exposed, e.g. by a crater, then it sublimates on short timescales. However, out of direct sunlight ice can remain stable on the surface of asteroids (and the Moon and Mercury) if it is located in permanently shadowed polar craters, where temperature may remain very low over the age of the Solar System (e.g. 30–40 K on the Moon).
Observations of the asteroid belt, located between Mars and Jupiter, suggest that the water snow line during formation of the Solar System was located within this region. The outer asteroids are icy C-class objects (e.g. Abe et al. 2000; Morbidelli et al. 2000) whereas the inner asteroid belt is largely devoid of water. This implies that when planetesimal formation occurred the snow line was located at around 2.7 AU from the Sun.[3]
For example, the dwarf planet Ceres with semi-major axis of 2.77 AU lies almost exactly on the lower estimation for water snow line during the formation of the Solar System. Ceres appears to have an icy mantle and may even have a water ocean below the surface.[6][7]
Just as zero is not equal to infinity, everything coming from nothing is illogical.
Closeup of Saturn's moon Iapetus. Photo:
NASA/JPL/Space Science Institute/Cassini.
You're right about the snow line and about snow in space, Bruce. After all, who can deny that the "white face of two-faced moon Iapetus", moon of Saturn, looks exactly as i f it had been covered in snow? And you know, if it walks lika a duck...
Jets of Enceladus. NASA/JPL/Space Science Institute/Cassini.
And who's to say that that's not snow coming out of Enceladus? Yes, it must be water when it first bursts through the cracks of the ice shield of Enceladus, but it must turn into ice particles - snow - very quickly.
I really like this picture which shows tiny Enceladus basically creating the E ring of Saturn.
Observations of the asteroid belt, located between Mars and Jupiter, suggest that the water snow line during formation of the Solar System was located within this region. The outer asteroids are icy C-class objects (e.g. Abe et al. 2000; Morbidelli et al. 2000) whereas the inner asteroid belt is largely devoid of water. This implies that when planetesimal formation occurred the snow line was located at around 2.7 AU from the Sun.
For example, the dwarf planet Ceres with semi-major axis of 2.77 AU lies almost exactly on the lower estimation for water snow line during the formation of the Solar System. Ceres appears to have an icy mantle and may even have a water ocean below the surface.
<<Ceres appears to be partially differentiated into a muddy (ice-rock) mantle, with a crust that is 60 percent rock and 40 percent ice. It probably no longer has an internal ocean of liquid water, but there is brine that can flow through the outer mantle and reach the surface.
The geology of Ceres is driven by ice and brines, with an overall salinity of around 5%. It is thought to consist of an inner muddy mantle of hydrated rock, such as clays, an intermediate layer of brine and rock (mud) down to a depth of at least 100 km, and an outer, 40-km thick crust of ice, salts and hydrated minerals. It's unknown if it contains a rocky or metallic core, but the low central density suggests it may retain about 10% porosity. Altogether, Ceres is approximately 40% or 50% water by volume, compared to 0.1% for Earth, and 73% rock by weight. It is not possible to tell if Ceres' deep interior contains liquid or a core of dense material rich in metal.
Cryovolcanoes such as Ahuna Mons form at the rate of about one every fifty million years. In January 2014, emissions of water vapor were detected from several regions of Ceres. This was unexpected because large bodies in the asteroid belt typically do not emit vapor, a hallmark of comets.>>
Apollo 17's Moonship
