In addition to this, Planck is also undertaking a few other observations of nearer things, such as parts of our own Milky Way galaxy.  As the most sensitive instrument of its kind, it can see things with a greater clarity, resolution and range of wavelengths than ever before, and scientists have several targets selected for it.

The rocket that took Planck into space was an Ariane 5, the ESA’s standard launch vehicle.  The launch took place on May 14, 2009, from the ESA spaceport in Kourou, French Guiana.  As a cost-saving measure, Planck was launched along with another probe, the Herschel infrared observatory.  These two probes separated from their launcher soon after reaching space.  Both of them were sent on a course that would eventually lead them to the second Lagrangian point (L2), situated about 1.5 million km. from Earth in the opposite direction from the sun.

These two probes will operate independently of each other, but the science they  do will be complementary.  The Herschel infrared observatory is also an interesting subject, and will be examined further in a future article at this site.  For now, we will concentrate on Planck.

The Planck satellite weighed about 1900 kg. at launch, and has a boxy shape about 4.2 meters on a side.  It is equipped with a 1.5-meter-wide mirror which focuses radiation from the sky and sends it to two detectors known as the Low Frequency Instrument and the High Frequency Instrument.

The Low Frequency Instrument (LFI) performs observations of the microwave sky in the range of frequencies from 27 to 77 GHz.  It is composed of 22 tuned radio receivers which work like the transistors in a radio, amplifying the signal and converting it into a voltage.  The High Frequency Instrument (HFI) performs observations in the range from 84 GHz to 1 THz.  It has 52 bolometric detectors , devices capable of measuring very small amounts of heat energy.  The results from these two instruments are complementary, and go together to form the total mission results.

The instruments are very sensitive to heat, and the probe’s designers had to include a cooling system and various other measures to ensure a stable, low temperature.  In fact, the reason why Planck orbits the sun at the L2 point, rather than orbiting Earth, is that both Earth and the moon give off too much heat.  Planck had to get some distance away from them, or their heat would have spoiled the observations.

Planck is equipped with its own thrusters, and these were used for three course correction maneuvers.  The third of these maneuvers took place on July 2, and injected the probe into its orbit around the L2 point.

Because of the temperature constraint, it was necessary to put the probe through a cooling process before it could go into operation.  The instruments hit their lowest temperature, 0.1K above absolute zero, in the first week of July.  During the cooling period, all of the satellite’s subsystems were also turned on and tested.

Planck was designed to give answers to some of the most fundamental questions in cosmology: how did the universe begin, how did it evolve to the state that it is in today, and how will it evolve in the future?  The Cosmic  Microwave Background  carries information about the processes that took place in those early moments of existence, and by analyzing it, scientists can look through a window in time, to the moment right after creation.

This information takes the form of tiny temperature fluctuations in the CMB, about a millionth of one degree.  This is the equivalent of detecting the body heat of a rabbit sitting on the moon from Earth.

Planck’s first task was the First Light Survey, which was really just a chance to check the sensitivity of the instruments and make sure they could perform as expected.  The scientists were delighted to find that the quality of the data was excellent.

Since then, Planck has been working on its first All-Sky Survey.  This began in mid-August 2009, and is being completed now.  As of mid-March 2010, 98% of the sky had been observed by Planck, and 100% sky coverage is expected by late May 2010.

However, before the raw data can be turned into sky maps of the CMB, it will require a lot of delicate adjustments and careful analysis.  About two years will be need to refine the information and obtain the scientific results.  Even then, the resulting maps will provide decades of work for cosmologists and astrophysicists as they continue to study and analyze them.

One of the things they’ll be looking for will be confirmation of the current theory of how the universe formed.  This is one of those sticky moments in science when the scientific authorities have a theory that explains everything beautifully, but they don’t have a shred of evidence to support it- or to disprove it, for that matter.  The theory is called the inflation model, and the condensed version runs something like this:

(What came before the Big Bang, we have no idea.  All of our theories of the evolution of the universe deal with what happened after that event, and if anything came earlier, we probably will never know about it.)

The universe begins as an extremely small point.  During the first millionth of a second of its existence, it rapidly expands, or “inflates.”  After this initial burst of expansion, it continues to grow at a slower rate, and as it grows, the thermal energy which it contains becomes spread out over a larger area.  This means that the universe cools as it expands.

When the temperature of the universe drops to 1000 GeV (about 10 million million degrees) the natural forces appear: gravity, electromagnetism, and the strong and weak nuclear forces.  Quarks, the things that will form matter, appear and wander freely through the universe. As the universe keeps cooling, these quarks will eventually combine to form protons and neutrons, but it will still be too hot for them to capture electrons and make real elements.  Since electrons aren’t being captured to form atoms, they are free to interact with photons (light particles).  Because of this, a photon can’t travel very far without encountering an electron, and light does not propagate freely.  Because of this, the universe is dark.   It is only after 300,000 years that the universe cools enough to allow protons to capture electrons and form hydrogen atoms, which finally allows light to propagate freely. Light comes to the universe, and that first burst of light is the Cosmic Microwave Background.

Matter begins to form clots due to gravity, and as these clots grow, the universe takes on a more familiar appearance.  Stars form, and these form galaxies.

Fast-forward to today, and we see around us a universe filled with structures.  Galaxies form clusters, clusters form sheets and streamers spanning vast distances.  Where did all the structure come from?  If the universe all expanded out of one tiny point, why isn’t it uniform?  Why is matter gathered in some areas, while it seems to be more diffuse in other places?

The inflation theory explains the elaborate structures in the universe, which result from an uneven distribution of matter, by saying that they are the expansion of tiny variations in the original point from which it all expanded, and the expansion happened so suddenly that those variations were preserved, in vastly greater size, as the unevenness of matter in the universe today.

In other words, there has always been an unevenness in the distribution of matter and energy (as well as dark matter and dark energy).  This goes all the way back to the first instant of expansion, and since the CMB comes from close to the first moment (300,000 years is not very long in universal terms) it should have this unevenness, too.  It should also carry various other information from that early time, which Planck’s instruments can coax from it.  As a snapshot of the universe at a young age, it should have things to tell us about how the universe started, and how it got like it is today.

These are the kind of cosmic questions that Planck was designed to address.  Along the way, it will also do some viewing closer to home.  In fact, just a few days ago, the ESA released spectacular pictures taken by Planck showing filaments of cold dust only a few hundred lightyears away.  In addition to its work relating to the CMB, Planck will be doing studies of this nature, investigating structure and evolution on a galactic scale.

Planck is just getting started, and the clarity and resolution of the data so far promises great things for the future.  The questions that it addresses are of the most fundamental nature: how did it all begin, and how did it get like it is now?  You can’t get more cosmic than that.

As new data comes in from Planck, you can find it here.

Sources:

ESA Space Science: Planck Overview at website of European Space Agency:  esa.int/esaSC/120398_index_0_m.html

ESA Planck homepage at website of European Space Agency:  esa.int/SPECIALS/Planck/index.html

“Planck at a Glance: ESA’s Microwave Observatory” at website of European Space Agency:  esa.int/SPECIALS/Planck/SEMWN20YUFF_0.html

ESA Planck: Science Objectives at website of European Space Agency:  esa.int/SPECIALS/Planck/SEM0P20YUFF_0.html

ESA Planck: Planck Highlights at website of European Space Agency:  esa.int/SPECIALS/Planck/SEMKO20YUFF_0.html

ESA Planck: Instruments at website of European Space Agecny:  esa.int/SPECIALS/Planck/SEMBU20YUFF_0.html

ESA Planck: Launch and Early Operations at website of European Space Agency:  esa.int/SPECIALS/Planck/SEMB030YUFF_0.html

ESA Science and Technology: Planck at website of European Space Agency:  sci.esa.int/science-e/www/area/index.cfm?fareaid=17

ESA News: “Planck Sees Tapestry of Cold Dust” at website of European Space Agency:  esa.int/esaCP/SEMMN9CKP6G_index_0.html

ESA Space Science: “So How Everything Start?— a Timeline for the Universe” at website of European Space Agency:  esa.int/esaSC/SEMC6TS1VED_index_0.html

With this heightened telescopic acuity, there has been a flurry of research concerning a period of early galaxy formation known as the reionization epoch, a period that has remained largely a mystery up until now. A recent study by an American and Japanese team of astronomers led by Carnegie Observatory’s Masami Ouchi, has been able to precisely determine the age and distance of some of the universe’s oldest galaxies, and in doing so has answered a question that has been puzzling astronomers for ages.

The Big Bang, an event estimated to have occurred approximately 13.7 billion years ago, created a hot, chaotic soup of free-floating atomic particles. A mere 400,000 years later, the atomic particles combined to form neutral hydrogen molecules, or H₂. Sometime in the next 600,000 years, these neutral hydrogen molecules began to form enormous stars, which in turn emitted radiation and newly charged hydrogen ions, clearing the soup and allowing visible light to be emitted.

This much has been known for some time, but what has puzzled scientists up until very recently was how long, exactly, after the formation of the neutral hydrogen particles did reionization occur? Furthermore, when it did occur, did it happen suddenly, like the Big Bang itself? Or was it a gradual process, evolving over time?

Using the WFC3 as well as the Subaru telescope (from the National Astronomical Observatory of Japan) and the Spitzer telescope (out of California), researchers are able to calculate the specific wavelength of some of these earliest galaxies, which can then be used to calculate the galaxy’s distance and age. To do this, scientists view the distant stars through a progression of red light filters. As the filters increase in wavelength, or redness, distant stars will drop out of view, based on the wavelength of light they themselves are emitting. The last stars to drop out of view are determined to be the oldest stars, and as such are the stars of greatest interest to Ouchi and colleagues.

By examining density and brightness measurements, the team calculated that star formation and ionization rate was significantly lower from about 800 million to 1 billion years after the Big Bang than it was after that period. The low rate of ionization indicates that the reionization period must have started no less than 600 million years after the Big Bang.

The low rate of ionization during the period was the most unexpected finding, contradicting inferences made from previous studies.  This could be partially explained by a difference in the types of stars that were formed during the period”stars produced in the early galaxies were massive, containing up to 200 times more matter than our sun. These massive stars produced more ionizing photons than would a greater number of smaller stars, and thus might have given the illusion of a higher ionization rate.

A generation ago, this level of detailed research was the stuff of science fiction. Now, with technology advancing at an almost exponential rate, we can only imagine the possibilities that lie ahead.