ISS-RapidScat was a scatterometer instrument developed by NASA's Jet Propulsion Laboratory (JPL) to measure near-surface ocean wind speed and direction from the International Space Station (ISS). Operational from October 2014 to August 2016, it provided crucial data for weather forecasting, climate studies, and oceanographic research, demonstrating the utility of the ISS as a platform for Earth science missions.
Overview
ISS-RapidScat was a spaceborne Ku-band scatterometer, designed to provide continuous, global measurements of ocean surface wind vectors (both speed and direction). The instrument was largely built using spare parts from the defunct QuikSCAT mission, enabling a rapid and cost-effective development. Its deployment on the International Space Station represented a novel approach to Earth observation, leveraging the ISS's existing infrastructure and unique orbital characteristics.Mission Objectives
The primary objectives of the ISS-RapidScat mission included:- Global Wind Measurement: To provide continuous, near-real-time measurements of ocean surface wind speed and direction.
- Weather Forecasting: To support operational weather forecasting, particularly for the prediction and tracking of tropical cyclones and severe weather events.
- Climate Research: To extend the long-term data record of ocean winds, contributing to a better understanding of Earth's climate system and its changes.
- ISS Platform Demonstration: To demonstrate the feasibility and utility of the International Space Station as a flexible, cost-effective platform for deploying Earth science remote sensing instruments.
- Data Continuity: To bridge the gap in scatterometer data availability following the loss of the SeaWinds instrument on the ADEOS-II satellite and prior to the launch of future dedicated missions.
Instrumentation
ISS-RapidScat utilized a rotating, parabolic dish antenna that emitted microwave pulses at Ku-band frequencies (13.4 GHz) towards the ocean surface. The instrument then measured the backscattered radar signal. The strength and characteristics of this scattered signal vary directly with the roughness of the ocean surface, which in turn is primarily influenced by wind speed and direction. The instrument was robotically mounted on the exterior of the European Space Agency's Columbus module on the ISS.Deployment and Operations
ISS-RapidScat was launched aboard a SpaceX Dragon cargo spacecraft (CRS-4) on September 21, 2014, from Cape Canaveral, Florida. It was robotically installed on the exterior of the ISS's Columbus module on September 26, 2014. Following a calibration and commissioning phase, the instrument began full operational science data collection in October 2014.Unlike sun-synchronous polar-orbiting satellites, the ISS-RapidScat's non-sun-synchronous orbit meant it observed different times of day over a specific location, providing valuable insights into the diurnal cycle of ocean winds that sun-synchronous satellites often miss.