— NASA's Hubble confirms that galaxies are the ultimate recyclers — New observations by NASA's Hubble Space Telescope are expanding astronomers' understanding of the ways in which galaxies continuously recycle immense volumes of hydrogen gas and heavy…
— Frozen comet had a watery past, University of Arizona scientists find — For the first time, scientists have found convincing evidence for the presence of liquid water in a comet, shattering the current paradigm that comets never get warm enough to melt…
— Sugar-grain sized meteorites rocked the climates of early Earth and Mars — Bombardments of 'micro-meteorites' on Earth and Mars four billion years ago may have caused the planets' climates to cool dramatically, hampering their ability to support life, according…
— Astrophysicist: White dwarfs could be fertile ground for other Earths — Planet hunters have found hundreds of planets outside the solar system in the last decade, though it is unclear whether even one might be habitable. But it could be that the best place…
— Integral spots matter a millisecond from doom — ESA's Integral gamma-ray observatory has spotted extremely hot matter just a millisecond before it plunges into the oblivion of a black hole. But is it really doomed? These unique observations…
— MESSENGER spacecraft to swing into orbit around Mercury — At 8:45 p.m. EDT on March 17, the MESSENGER spacecraft will execute a 15-minute manoeuvre that will place it into orbit around Mercury, making it the first craft ever to do so, and…
— Baby stars born to 'napping' parents — Cardiff University astronomers believe that a young star's long 'napping' could trigger the formation of a second generation of smaller stars and planets orbiting around it…
— Oldest objects in solar system indicate a turbulent beginning — Scientists have found that calcium, aluminium-rich inclusions (CAIs), some of the oldest objects in the solar system, formed far away from our sun and then later fell back into the…
— Oxygen isotope analysis tells of the wandering life of a dust grain 4.5 billion years ago — Scientists have performed a micro-probe analysis of the core and outer layers of a pea-sized piece of a meteorite some 4.57 billion years old to reconstruct the history of its formation,…
Coolest spacecraft ever in orbit around second Lagrange point
On 2 July, the detectors of Planck's High Frequency Instrument reached their amazingly low operational temperature of -273 C, making them the coldest known objects in space. The spacecraft has also just entered its final orbit around the second Lagrange point of the Sun-Earth system, or L2.
Planck is equipped with a passive cooling system that brings its temperature down to about -230 C by radiating heat into space. Three active coolers take over from there, and bring the temperature down further to an amazing low of -273.05 C, only 0.1 C above absolute zero - the coldest temperature theoretically possible in our Universe.
Such low temperatures are necessary for Planck's detectors to study the Cosmic Microwave Background (CMB), the first light released by the universe only 380 000 yrs after the Big Bang, by measuring its temperature across the sky.
The detectors will look for variations in the temperature of the CMB that are about a million times smaller than one degree - this is comparable to measuring from Earth the heat produced by a rabbit sitting on the Moon. This is why the detectors must be cooled to temperatures close to absolute zero ( - 273.15 C, or zero Kelvin, 0K).
Details on the different stages of the cool-down process are available via the 'Planck in depth' link at right.
Starting at 13:15 CEST 2 July, the Planck Mission Control Team conducted a crucial orbit insertion manoeuvre designed to place the satellite into its final orbit about L2.
Once commanded, the burn was auto-controlled by Planck, with the thrusters operating for between 12 and 24 hours. The manoeuvre directed the satellite into its final operational orbit around the second Lagrange point of the Sun-Earth system, L2.
The thruster burn was planned to deliberately underperform by a small margin, necessitating a small 'touch up' manoeuvre in the coming days to bring the satellite fully onto its planned trajectory.
'While this manoeuvre itself is routine, it represents the final major step in the long voyage to L2, and everyone here is quite happy to see Planck getting into its operational orbit,' said Chris Watson, Spacecraft Operations Manager, speaking in the mission's Dedicated Control Room at ESA's European Space Operations Centre, Darmstadt, Germany.
The manoeuvre was planned to change the satellite's speed by 211.6 km/hour, ending with a final speed of 1010 Km/hour with respect to the ground. Together with Earth and the virtual point L2, Planck will then be orbiting the Sun at a speed of 106 254 km/hour (29.5 km/second).
At the start of 2 July's manoeuvre, Planck was located 1.43 million km from Earth.
All commissioning activities are on schedule, and this phase of the mission is practically complete. Over the next few weeks, the operation of the instruments will be fine-tuned for best performance.
Planck will begin to survey the sky in mid-August.
Or subscribe for our Newsletter, a free e-mail publication. It is published practically every day.
How white dwarfs get their kicks
Noctis Labyrinthus, labyrinth of the night
An X-Ray Santa Claus in Orion
Holiday wishes from the Hubble Space Telescope