The Planck Satellite
Matthew Trimble
10/1/12
Useful Physics
• Observing at a redshift = looking at light from
a very distant object that was emitted a long
time ago
• The ‘temperature’ of the CMB is the
temperature of a blackbody that would emit
the energy spectrum seen by the photons
• Fun Fact: CMB is most ideal blackbody
spectrum ever recorded
Need For Planck
• Space vs. Ground telescopes
• Hubble: Launched 1990
• WMAP: Launched 2001, now in graveyard
orbit
• Planck: Launched 2009
• Better resolution of CMB
Spacecraft Design
• ~4.2 m high X 4.2 m wide
• 1.95 tonnes
• Three stage cooling system and shielding from
Sun to minimize background radiation
• 1.9 m x 1.5 m primary mirror
• Lifetime: 15+ months, dependant on cooling
system degradation
• Propulsion: 12 20N thrusters, 4 1N thrusters
Special Orbit
• Lissajous Orbit around L2
• Propulsion only needed for corrections
Instruments
• Telescope: 1.9 x 1.5 m primary mirror,
effective aperture of 1.5 m.
• Low Frequency Instrument: observes
wavelengths from 3.9 mm to 11.1 mm.
• High Frequency Instrument: observes from .3
mm to 3.6 mm.
Cosmic Microwave Background
• After Big Bang, radiation and matter were
coupled (no light emitted)
• As expanding universe cooled, it reached 3000K
at matter began thermally radiating photons
• This radiation is the CMB, which has now
increased wavelength to the microwave, and
‘cooled’ to ~2.7K
• CMB temperature is not homogenous, but early
measurements were not able to detect the tiny
fluctuations
Large Scale Properties of Universe
• Large scale properties: density, number of
atoms in visible universe, etc.
• Planck will be able to accurately measure how
certain properties (density) evolved over time.
• That data allows other properties (# atoms) to
be determined with low uncertainty.
Dark Matter
• Doesn’t interact with radiation, therefore it is
literally dark.
• Presence can only be inferred by gravitational
interactions with luminous matter.
• Planck will detect the gravitational lensing the
CMB undergoes due to dark matter.
Inflation
• The theorized extremely rapid expansion of
the early universe.
• Currently explains much of the Universe’s
features.
• Planck will investigate possible causes of
inflation, and try to determine if expansion
will continue, or if the universe will eventually
collapse in a Big Crunch.
Primordial Gravitational Waves
• Hypothesized to exist during inflation.
• Gravitational waves carry information about
the event that triggered the wave.
• Detecting these ancient waves through the
CMB would give strong evidence for Inflation.
Inhomogeneities of Early Space
• Our universe is not homogenous: full of galaxy
clusters and large voids.
• Likely, there were inhomogeneities very early
on, which formed into the complex structures
we have today.
Microwave Study of Galaxies
• Milky Way: create the first map the cold dust
distributed along spiral arms, and the first
detailed, 3D map of the Milky Way’s magnetic
field.
• Other: Using the Sunyaev- Zel'dovich effect,
Planck can catalogue distant galaxy clusters.
Conclusion
• “Planck will measure the fluctuations of the
CMB with an accuracy set by fundamental
astrophysical limits.”
• Planck has the capabilities to verify a large
portion of cosmology and particle physics that
has yet to be figured out.
• Data will not be released until 2013, but the
astrophysical community overall expects good
results from Planck.
References
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1. http://www.esa.int/SPECIALS/Planck/SEMWN20YUFF_0.html
2. http://en.wikipedia.org/wiki/Lissajous_orbit
3. http://en.wikipedia.org/wiki/Lagrangian_point#L2
4. http://www.esa.int/SPECIALS/Planck/SEMQ05XX3RF_0.html
5. http://en.wikipedia.org/wiki/Planck_(spacecraft)
6. http://en.wikipedia.org/wiki/Inflation_(cosmology)
7. http://blogs.discovermagazine.com/cosmicvariance/2012/09/04/guestpost-doug-finkbeiner-on-fermi-bubbles-and-microwave-haze/
• 8. http://www.funtrivia.com/en/subtopics/Cosmic-MicrowaveBackground-Radiation-267543.html
• 9. http://news.sciencemag.org/sciencenow/2010/07/scienceshot-plancksatellites-fi.html