Discovering the Universe with the Wilkinson Microwave Anisotropy Probe (WMAP)

Discovering the Universe with the Wilkinson Microwave Anisotropy Probe (WMAP)
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The Wilkinson Microwave Anisotropy Probe or WMAP is a NASA Explorer mission that was launched in 2001 to make measurements of

cosmology on a fundamental level. It is an orbiting satellite that can detect microwave radiation that is being used to validate many of our new theories of the universe and create new ones. WMAP was the brainchild of John Hopkins Professor Charles L. Bennet starting in 1995, and selected as an Explorer Mission in 1996. The satellite made its launch from Cape Canaveral on June 30, 2001, and made several ’loops’ between the Earth and the Moon. With assistance from the Moon’s gravity, WMAP went on to be the first satellite to occupy the Earth’s second Lagrange point. The L2 Lagrange point is a stable orbit ‘behind’ the Earth so that it always stays in the same place with relation to the Earth.


WMAP completed its 2-year mission in 2003, but the Astronomy and Physics Senior Review granted WMAP mission extensions that would endorse the satellite for another 9 years, ending finally in September 2010. Since the start of the mission, WMAP has produced data that resulted in 37 papers that are free and open to the public. Since 2000, the three most highly cited scientific papers in physics and astronomy have come from the WMAP program. While the Hubble telescope blesses the world with amazing pictures, the WMAP provides us with a much better understanding of the universe and our place in it.


  1. WMAP has created the first fine-resolution, full sky map of the microwave background radiation.

WMAP’s Trajectory

  1. WMAP has definitively determined the age of the universe to be 13.73 billion years, give or take 120 million years.

  2. WMAP has determined the curvature of the universe within 1 percent to be a ‘flat’ Euclidian shape.

  3. Baryonic matter, or matter made of atoms like you and me, only make up 4.6 percent of the universe.

  1. Dark matter, which is a mysterious form of matter not made of atoms, makes up 23.3 percent of the universe.

  2. The amazing accuracy and precision of WMAP have been able to determine that dark energy makes up 72.1 percent of all energy in the universe, causing the expansion rate of the universe to speed up.

  3. The Wilkinson Microwave Anisotropy Probe has started probing the very first instances of the universe, down to the first trillionth of a trillionth of a second, ruling out well-known textbook models for the first time.

Just the Facts

Mass: 840 kg

WMAP’s orbit at the Earth’s L2 point

Power: 419 Watts

Cooling System: Passively cooled to 90 K

Launch: Delta II Rocket on June 30, 2001

Orbit: 1- 10 degrees about second Lagrange point

Trajectory: 3 Earth-Moon loops before lunar gravity assist to L2

Design Lifetime: 27 months for Earth-Moon loops, 2 years at L2





Delta II

WMAP Trajectory