MAP Mission Overview

Primary science: To probe conditions in the early universe by measuring the properties of the cosmic microwave background radiation over the full sky.
Instrument: Passively cooled differential microwave radiometers with dual Gregorian 1.4 x 1.6 meter primary reflectors.
Payload: MAP will launch in Fall 2000 on a Med-Lite Delta II 7425-10 vehicle into a lunar assisted trajectory to the Sun-Earth L2 libration point for a nominal 27 month mission. The total payload mass is 800 kg.

To addresses its key scientific questions, MAP measures small fluctuations in the temperature of the cosmic microwave background radiation. These temperature fluctuations are minute: one part of the sky has a temperature of 2.7281 Kelvin (degrees above absolute zero), while another part of the sky has a temperature of 2.7279 Kelvin. NASA's Cosmic Background Explorer (COBE) satellite, has detected these tiny fluctuations on large angular scales. MAP will measure anisotropy with much higher resolution and sensitivity than COBE did.

These measurements should reveal the size, matter content, age, geometry and fate of the universe. They will also reveal the primordial structure that grew to form galaxies and will test ideas about the origins of these primordial structures.

The MAP instrument consists of a set of passively cooled microwave radiometers with 1.4 x 1.6 meter diameter primary reflectors to provide the desired angular resolution. Measuring the temperature of the microwave sky to an accuracy of one millionth of a degree requires careful attention to possible sources of systematic errors. The avoidance of systematic measurement errors drove the design of MAP:

• The instrument has five frequency bands from 22 to 90 GHz to facilitate separation of Galactic foreground signals from the cosmic background radiation.

• MAP is a differential experiment: if you would like to know whether one piece of wood is longer than another, it is better to put the pieces directly next to each other than to measure them separately with a ruler. MAP measures the temperature difference between two points in the sky rather than measuring absolute temperatures.

• An orbit about the Sun-Earth L2 libration point that provides for a very stable thermal environment and near 100% observing efficiency since the Sun, Earth, and Moon are always behind the instruments field of view.

• A scan strategy that rapidly covers the sky and allows for a comparison of many sky pixels on many time scales.

Many more details about the experiment available in the MAP technical information pages.

MAP will launch in Fall 2000 on a Med-Lite Delta II 7425-10 vehicle into a lunar assisted trajectory to the Sun-Earth L2 libration point for a nominal 27 month mission (3 months transit to L2, 24 months observing). The total payload mass is 800 kg. The MAP instrument will be continuously shaded from the Sun, Earth, and Moon by the spacecraft.

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Last updated: Friday, 05-21-1999