Comet crystals feel the heat

Since comets formed out in the cold depths of the Solar System, the existence of materials in them that must have been created in high temperatures has been a real puzzle, until now. NASA’s Spitzer Space Telescope has observed the infrared signature of tiny silicate crystals, of the type found in comets, being created in the planet-forming disc around a young star called EX Lupi, in the constellation of Lupus.

The stellar outbursts occur when the growing young star accumulates a large amount of mass from the dusty, gaseous disc that is spinning around it. Each outburst sends a flash of heat permeating through the disc. At the distance the crystals were seen at, the temperature reached 725 degrees Celsius (about 1,000 kelvin), enough to thermally ‘anneal’ the silicate dust.

Graveyards of solar systems around dead suns

Using NASA's Spitzer Space Telescope to study white dwarf stars, astronomers have found the dusty remains of ancient solar systems.

White dwarfs are the dense glowing embers of Sunlike stars. While their atmospheres should consist entirely of hydrogen and helium, they are sometimes contaminated with heavier elements like calcium and magnesium.These metals really shouldn't be there.That means they are external pollutants.

The rocky debris imaged by Spitzer probably represents the innermost planets of a solar system that were ripped apart by the gravitational forces of their host star at the end of its life. Extrapolating our own Sun's life into the white dwarf phase, simulations show that the Earth may not survive, but that Mars and asteroid belt would probably lie outside of the Sun's grasp.

Perhaps the most exciting and important aspect of this research is that the composition of these crushed asteroids can be measured using the heavy elements seen in the white dwarf. In one case 17 heavy elements were found in one star, yielding a composition that closely matches the equivalent of a combined Earth and Moon. The next step will be to search for those ingredients that may suggest that life-bearing planets may once have existed in these systems.

Spitzer Space Telescope to embark on new, warmer life

Scientists are bracing for the loss of two key instruments aboard NASA's infrared Spitzer Space Telescope, which will considerably diminish the observatory's ability to image infant stars but unlock more time for more thorough studies of mysterious worlds outside the solar system.

Officials expect Spitzer will drain its supply of liquid helium some time next month, reducing the telescope's sensitivity to infant stars and distant galactic nuclei.

Engineers have calculated the helium will probably run out around May 12.

Spitzer, the last of NASA's Great Observatories designed to revolutionize astronomy, was launched in 2003 with about 95 gallons of frigid liquid helium chilled to about -457 degrees Fahrenheit. That number equates to 1.2 degrees Kelvin, nearly as cold as the point of absolute zero.
The spacecraft was launched at room temperature and the cryogenic helium began cooling the 33.5-inch-diameter telescope before operations began in late 2003.

Sensors for the observatory's three science instruments are mounted inside a structure called the cryostat, which is actively cooled by vapors vented from the adjacent liquid helium tank.
The instruments must be maintained at such cold temperatures to see through relatively cool dust clouds and observe star-forming regions hidden from optical telescopes.
When Spitzer empties the liquid helium tank, the spacecraft will automatically detect the slight warming of the cryostat.

The spacecraft will go into a planned anomalous condition, basically a standby mode.

It will take about a day to recover from the fault, and then the Spitzer ground team will begin monitoring the telescope as the cryostat warms to about 30 degrees Kelvin, still a bone-chilling -405 degrees Fahrenheit.

Assuming Spitzer runs out of helium in the middle of May, scientists hope to begin "warm" operations by the end of June.
Scientists will only be able to use part of the capacity of Spitzer's Infrared Array Camera, an instrument with four detector channels ranging from near-infrared to mid-infrared wavelengths.
Warm observations will be limited to two wavelengths in the near-infrared spectrum.