After 10 years, space'craft' Rosetta is now arriving at Comet 67P/Churyumov–Gerasimenko. The little lander Philae is scheduled to land in November 2014. A major assumption of its design is that the comet is made from ice, a dirty snowball. But a first temperature measurement from 5km distance now says:
It is one data point suggesting that comets are not just "dirty snowballs". We'll see what it actually is made of in the next months, and if the Lander will be able to use it's harpoons and screws to attach itself to the surface (which might be difficult when it's rock-hard). It will also be interesting to see if the -70°C infrared measurement is actually correct, since Robitaille argued that Kirchhoff's law of radiation is not universal and that it strongly depends on the material: _https://www.youtube.com/watch?v=3Hstum3U2zw (Robitaille, "On the validity of Kirchhoff's law")
_https://rosetta.jpl.nasa.gov/news/rosetta-takes-comets-temperature said:ESA’s Rosetta spacecraft has made its first temperature measurements of its target comet, finding that it is too hot to be covered in ice and must instead have a dark, dusty crust. ... using the sensor to collect infrared light emitted by the whole comet, scientists determined that its average surface temperature is about –70ºC. ... Although –70ºC may seem rather cold, importantly, it is some 20–30ºC warmer than predicted for a comet at that distance covered exclusively in ice.
It is one data point suggesting that comets are not just "dirty snowballs". We'll see what it actually is made of in the next months, and if the Lander will be able to use it's harpoons and screws to attach itself to the surface (which might be difficult when it's rock-hard). It will also be interesting to see if the -70°C infrared measurement is actually correct, since Robitaille argued that Kirchhoff's law of radiation is not universal and that it strongly depends on the material: _https://www.youtube.com/watch?v=3Hstum3U2zw (Robitaille, "On the validity of Kirchhoff's law")