Mission

Launch of six microsatellites into low-Earth orbit to form the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC)

When & Where

Launch scheduled for
April 14, 2006
5:10 p.m. PDT (8:10 p.m. EDT)
Vandenberg Air Force Base, California

Why

Related visual:
A. COSMIC Soundings.

COSMIC will nearly triple the amount of high-resolution data available in real time to atmospheric researchers and forecasters for weather forecasting, monitoring of climate change, and space weather research.

Who

A joint effort between the United States and Taiwan.  In Taiwan the project is called FORMOSAT-3.

Participants and Costs

Total cost is approximately $100 million

Taiwan
National Science Council and National Space Organization are providing over $80 million for the system

United States
The National Science Foundation, lead agency for COSMIC science activities, and its partners are providing the rest of the support. 
In addition to NSF and UCAR, major partners include

• NASA
• NOAA
• U.S. Air Force
  • USAF Space Test Program
  • Air Force Office of Scientific Research
• Office of Naval Research
• Department of Defense Space and Missile Systems Center's Rocket Systems Launch Program of the U.S. Air Force, which also provided logistical support
• Orbital Sciences Corporation designed the spacecraft
• NASA's Jet Propulsion Laboratory designed and produced the prototype high-performance GPS science receiver
• Broad Reach Engineering built the receivers for the satellite constellation
• The Naval Research Laboratory designed and built the ionospheric sensors
• The rest of the constellation was built and tested in Taiwan.

Launch vehicle

Minotaur rocket operated by the U.S. Air Force, manufactured by Orbital Sciences Corporation

Spacecraft

Related visuals:
B. FORMOSAT-3/COSMIC Video. Satellite interior, showing placement of three onboard instruments at 00:52.

D, E, F, and G. Photos and illustration of spacecraft

Six microsatellites

Measurements for each individual satellite:

• weight: 155 pounds (70 kilograms)
• diameter: 40.2 inches (103 centimeters)
• width: 6.2 inches (16 centimeters)

Each satellite carries three instruments on board:

• GPS radio occultation receiver
• Tiny Ionospheric Photometer (TIP, to measure electron density)
• tri-band beacon (to relay data to ground stations)

Other system components

Satellite operations control center at the National Space Organization (NSPO) in Hsin-Chu, Taiwan

Data-receiving ground stations in Fairbanks, Alaska, and Kiruna, Sweden.

COSMIC Data Analysis and Archive Center at the University Corporation for Atmospheric Research (UCAR) in Boulder, Colorado

A network of fixed GPS receivers on the ground, called the global ground fiducial network, used for comparison with the satellite measurements.

Orbit

Related visual:
B. FORMOSAT-3/COSMIC Video. Animation of satellites orbiting in one plane, then separating into six different planes at 01:33.

During the first year after launch, onboard thrusters will gradually transfer the satellites from their initial orbital plane to six separate orbital planes. The initial injection orbit is at an altitude of 250 miles (400 kilometers) and final low-Earth orbit will be about 500 miles (800 km) above the surface.

During the boosting phase, COSMIC scientists will conduct experiments related to gravity and geodetics—the size and shape of Earth, and begin analyzing the quality of the first meteorological measurements.

Observation method: Radio occultation

Related visuals:
B. FORMOSAT-3/COSMIC Video. Animation of radio occultation at 00:16.

C. Radio Occultation. Illustration of occulting GPS and LEO satellites.

COSMIC will measure key attributes of the atmosphere using radio occultation, a method first developed in the late 1960s to study atmospheres on other planets by JPL and Stanford University. 

How radio occultation works

Specialized GPS receivers aboard COSMIC's six satellites will track signals from 24 U.S. Global Positioning System satellites.

Temperature, pressure, and moisture affect the density of the atmosphere. When radio signals from the higher-orbiting GPS satellites pass through the atmosphere, the signals' paths are bent and their progress is slowed.  The rate of these changes depends on the atmosphere's density along the path.

COSMIC's low-Earth-orbiting (LEO) satellites will take advantage of this effect by intercepting the GPS radio signals just above Earth's horizon and precisely measuring the bend and signal delay along the signal path. 

Radio occultation is useful for measuring electron density in the charged upper atmosphere (ionosphere) as well.

The satellites will downlink the raw data—measurements of changes in the amplitude and phase of radio waves—to ground stations in Fairbanks, Alaska, and Kiruna, Sweden for relay to the data analysis center in Boulder.

Additional observations from the Tiny Ionospheric Photometer (TIP)

A separate onboard instrument, a radiometer called the Tiny Ionospheric Photometer (TIP), will look down through the outer atmosphere to sense airglow, the light given off by electrons when solar activity ionizes molecules in this region.

What will be measured

At UCAR's COSMIC office in Boulder, scientists will analyze and convert the raw data into vertical profiles (high-resolution descriptions from the surface to 24 miles [40 km] above, in three dimensions), for these key attributes:

• water vapor (humidity)
• temperature
• pressure
• electron density in the upper atmosphere

Expected global benefits

Climate Science

• will provide highly accurate, global readings of Earth's temperature
• will help improve monitoring of long-term variation and change in Earth's climate
• will be used for testing and improvement of climate models

Meteorology

• will provide missing data from areas where observations by weather balloons are scarce, especially over the oceans, polar regions, and other remote areas
• will provide high-resolution water vapor data to help meteorologists observe, research, and forecast hurricanes, typhoons, and other storm patterns 
• will help improve the reliability of computer models used for global and regional weather prediction 

Ionosphere

• will provide global data on electron density, a key measurement for research on space weather

Gravity and Geodesy Studies

• will provide data to improve computer models of Earth's gravity field, which varies with variations in climate as fluids in the atmosphere, oceans, and other parts of the Earth system redistribute around the globe

Forecasting benefits for Taiwan 

• Typhoons, the name for hurricanes in the eastern Pacific, can be fierce and devastating over Taiwan.
• Too few weather-balloon soundings are made over the Pacific Ocean, where the storms spin up
• COSMIC will provide sufficient high-resolution data from the ocean surrounding Taiwan to improve typhoon forecasting, particularly forecasts of rainfall and wind strength.

Global data distribution

UCAR's COSMIC Data Analysis and Archive Center will provide

• rapid analysis of the data for use in experimental and operational forecasts
• near-real time data to U.S. and international universities and research centers via the Web
• an online data archive