Cyclone Global Navigation Satellite System

Cyclone Global Navigation Satellite System
Name	Cyclone Global Navigation Satellite System
Mission type	Earth observation, Hurricane research
Operator	University of Michigan, Southwest Research Institute, NASA
COSPAR ID	2016-074
SATCAT	41842–41849
Mission duration	Planned: 2 years, Elapsed: 7 years, 4 months, 24 days
Spacecraft	8 microsatellites
Manufacturer	Southwest Research Institute
Launch mass	28.9 kg each
Power	65 watts
Launch date	15 December 2016, 13:37 UTC
Launch rocket	Pegasus XL
Launch contractor	Northrop Grumman
Launch site	Cape Canaveral Space Force Station, L-1011 carrier aircraft
Orbit reference	Geocentric orbit
Orbit regime	Low Earth orbit
Orbit inclination	35°
Orbit period	95 minutes
Apsis	gee
Programme	NASA's Earth System Science Pathfinder
Previous mission	Orbiting Carbon Observatory 2
Next mission	Ecosystem Spaceborne Thermal Radiometer Experiment on Space Station

Cyclone Global Navigation Satellite System is a constellation of eight small satellites forming a spaceborne mission designed to measure ocean surface winds in and near the eye of tropical cyclones. Developed as part of NASA's Earth System Science Pathfinder program, the mission is a collaboration led by the University of Michigan with primary hardware development by the Southwest Research Institute. Its primary innovation is using reflected Global Positioning System signals to derive wind speed data, enabling more frequent observations of storm dynamics than traditional scatterometer instruments.

Overview

The mission represents a novel approach to Earth observation by utilizing existing L-band signals from the Global Positioning System constellation as a source for bistatic radar measurements. This technique allows the satellites to peer through heavy precipitation typical of the eyewall of intense storms like hurricanes and typhoons, a region where conventional satellite-based microwave radiometers and scatterometers often cannot retrieve accurate data. The project was selected in 2012 under NASA's competitive Earth Venture-class missions, which focus on innovative, cost-effective science.

Mission and objectives

The primary scientific objective is to significantly improve the understanding and forecasting of tropical cyclone intensity by measuring ocean surface wind speeds with unprecedented temporal resolution. Key goals include characterizing the inner-core wind fields of storms during their rapid intensification and decay phases, quantifying the relationship between ocean surface properties and heat flux in storm conditions, and extending the ability to monitor extreme weather events. Data from the constellation directly supports operational forecast models at centers like the National Hurricane Center and the Joint Typhoon Warning Center.

Satellite design and constellation

Each of the eight identical microsatellites is built on a standardized bus developed by Southwest Research Institute, with a mass under 29 kilograms. The constellation is deployed in a single orbital plane at an altitude of approximately 510 kilometers in a Low Earth orbit with a 35-degree inclination, providing frequent revisit times over the Earth's tropical cyclone basins. This specific orbital configuration ensures that multiple satellites pass over a developing storm every few hours, creating a dense network of wind observations that captures rapidly evolving storm dynamics.

Scientific instruments and data

The sole scientific payload on each satellite is the Delay Doppler Mapping Instrument, a specialized GNSS reflectometry receiver. It captures both direct signals from GPS satellites and signals reflected off the ocean surface, measuring their power, delay, and Doppler shift. These measurements are processed to calculate ocean surface roughness, which is directly related to wind speed. The raw data is downlinked to ground stations, including the NASA Earth Science Mission Operations center, and processed into wind speed products by the science team at the University of Michigan.

Mission development and launch

The mission was conceived by principal investigator Dr. Chris Ruf at the University of Michigan. Following its selection by NASA, the spacecraft were manufactured and tested by Southwest Research Institute in San Antonio. The complete constellation was launched on 15 December 2016 aboard a Northrop Grumman Pegasus XL rocket, which was air-dropped from an L-1011 carrier aircraft operating out of Cape Canaveral Space Force Station. The successful deployment of all eight satellites marked the first time NASA used a constellation of microsatellites for a major Earth science mission.

Scientific results and impact

Since becoming operational, data has led to breakthroughs in understanding tropical cyclone processes, particularly the role of rainfall and sea surface temperature in rapid intensification. Findings have been published in journals like Geophysical Research Letters and have been integrated into forecast models at the National Oceanic and Atmospheric Administration. The mission's success has also proven the value of GNSS reflectometry for oceanography, paving the way for future missions and inspiring similar techniques for soil moisture and flood mapping applications.

Category:NASA space probes Category:Earth observation satellites Category:Artificial satellites orbiting Earth Category:Spacecraft launched in 2016