John M. Grunsfeld, Ph.D.
Chief Scientist and Astronaut
National Aeronautics and Space Administration
Subcommittee on Environment, Technology, and Standards
Committee on Science
House of Representatives
October 30, 2003
Mr. Chairman and Members of the Subcommittee, thank you for the opportunity to testify before you today regarding the importance of space weather forecasting provided by the National Oceanic and Atmospheric Administration (NOAA) Space Environment Center (SEC) and its impact on NASA's programs. Providing space weather data is an important operational service, and it has a wide range of customers, both within the United States Government and in the private sector. My testimony today will focus on how NASA uses these critical data. I will speak to you from my perspective both as NASA's Chief Scientist, and as a member of the astronaut corps -- the group of people most directly exposed to the effects of space weather.
Solar wind conditions, solar flares, coronal mass ejections (CMEs), solar extreme ultraviolet emissions, and subsequent geomagnetic activity, commonly referred to as “space weather,” affect many more areas of NASA operations and programs than most people realize. Space weather can have significant adverse effects on human health and spacecraft operations by increasing the intensity of the near-Earth radiation environment, increasing atmospheric drag, disrupting satellite orientation, and degrading UHF and HF communications and Global Positioning System (GPS) signals. These affect the health of our astronauts in orbit, space engineering and research equipment functionality, orbital attitude for spacecraft such as the Hubble Space Telescope, and ultimately, the way we design spacecraft.
NASA's Space and Earth Science missions routinely employ real-time forecasts from the NOAA SEC to make decisions regarding data collection, spacecraft operations, and rocket launches. NASA engineers and researchers use near, real-time SEC forecasts to analyze instrument and spacecraft anomalies, and separate cause and effect in the highly modulated environment of space. During solar-induced changes to the near-Earth radiation environment, NASA's in-space research instrumentation can become saturated by solar energetic particles, which can lead to anomalies. This has happened numerous times during the recent maximum phase of the solar cycle. One example comes from the Earth Science Mission Operations (ESMO) Project. The ESMO uses data provided by the NOAA SEC to determine whether spacecraft anomalies are the result of system malfunctions or space weather events. Being able to determine quickly that an anomaly was caused by space weather allows ESMO to avoid lengthy equipment shutdowns while engineers search for a cause. NOAA SEC is the only operational source for accurate, real-time information on the near-Earth space radiation environment. NASA uses the lessons learned from these experiences and the database of radiation measurements gathered by SEC to design spacecraft with more robust systems that can withstand space weather events.
The Chandra X-Ray Observatory and the recently launched Space Infrared Telescope Facility both use the SEC observations of solar wind conditions and geomagnetic activity as a critical input to their real-time models of the Earth's radiation environment. These models allow us to adjust our operations to mitigate sensor degradation and data loss. The result is that NASA is able to ensure optimal scientific return from these two flagship missions. The SEC observations are also crucial to NASA-funded research exploring the Sun-Earth connection. The Sun affects the entire solar system, including all scientific data collection satellites.
At the NASA Johnson Space Center, the Space Radiation Analysis Group (SRAG) uses data provided by the SEC to determine the radiation environment in which NASA's crewed spacecraft will operate. NOAA has supplied space weather monitoring and forecasting information to NASA for every human space flight mission since Apollo 8. This information affects operational decisions, such as when to launch a particular Shuttle mission and when extravehicular activities (EVAs) can be safely conducted. Because of the information that the SEC provides, we can plan missions and on-orbit activities in such a way as to minimize the radiation exposure received by our astronauts and our vehicles.
Minimizing radiation exposure for Shuttle and International Space Station crews is imperative. NASA has sought the advice of the National Council on Radiation Protection and Measurements concerning radiation exposure limits for our astronauts, and uses this advice in setting radiation dosage limits. NASA's radiation protection efforts are further guided by the ALARA (As Low as Reasonably Achievable) principle. Without the data provided by SEC, NASA would have to reassess its operations to protect against exposure to radiation events occurring without warning.
Losing the SEC forecast that support space flight missions would be like living along a coastal area without any hurricane forecasting capability. You would know when the hurricane hit you, but you would have no advanced warning, no ability to take preventive actions, and no idea how strong it would be or how long it would last.
The risk that radiation poses to our spacecraft and astronauts is borne out by past examples. For instance, in 1989 significant solar events impacted both the Space Shuttle and the Mir space station, along with other uncrewed spacecraft. In the spring of 1989, a solar flare, solar particle event, and a geomagnetic storm doubled the daily radiation dose for the Mir crew for two days, with elevated levels lasting for two weeks. The solar events increased atmospheric drag during the first day of STS-29. NORAD lost track of several space objects for time periods varying from days to weeks. Several satellites lost attitude control, while others tumbled. These space weather events also brought the northeastern United States' power grid close to collapse. In the fall of 1989, a second series of solar particle events again raised the dose of the Mir crew and damaged satellite solar arrays.
The information provided by SEC is critical to NASA today as we operate the ISS until the Space Shuttle returns to flight. NASA has some monitoring capability on the ISS that we rely upon to gauge the safety of the ISS environment for the crew. Although we have tools that allow us to measure the radiation exposure of the crew and vehicle on a periodic basis, we cannot monitor it constantly. This equipment was designed as a back-up to the radiation monitoring and forecasting data provided by SEC, which allow flight controllers to notify the crew of increased radiation exposure levels. The SEC provides NASA with critical real-time monitoring and forecasting of the radiation environment around the Earth. We use this information along with on board instrumentation to assess the ISS radiation environment. In the current solar event, SEC forecasts gave us sufficient warning of a proton flux event to allow the ISS crew to shelter in areas of the ISS which provide more shielding protection from radiation.
NASA has a long history of cooperation with SEC and its predecessor organizations at NOAA. That partnership has enabled SEC to expand its capabilities to support human space flight missions. In the 1960s, NASA funded the development of the Solar Particle Alert Network (SPAN) to support the Apollo missions. NASA also supported the expansion of SEC services to support our Skylab missions. Most recently, we have helped SEC to modernize and add functionality to its data processing systems so that they can continue to support our Shuttle and ISS missions.
Building on the information and analysis provided by SEC, we have expanded our understanding of the impact of space weather on NASA's operations, and our ability to predict and respond to significant events. It is only in the past decade that we have realized that geomagnetic activity can enhance the outer electron belt, and increase radiation exposure for astronauts performing EVAs. During the same period, we have learned the important of CMEs with regard to solar flares in producing large proton events that can pose health risks to astronauts on orbit. NASA' Solar and Heliospheric Observatory (SOHO) has revolutionized our understanding of CMEs, providing real-time images of CMEs coming toward Earth. Perhaps most significantly, in the last several years, we have discovered definitive evidence of the magnitude and frequency of very large solar particle events over the past 400 years. These events were significantly larger than anything we have witnessed since humans started flying in space. It is likely that we will see a recurrence of solar particle events of a similar magnitude.
It is not within NASA's mandate as a research and development agency to provide the operational forecasting services currently provided by the SEC. In addition, the technical capacity, budget and expertise required to perform this activity could not transition to NASA without impacting our other ongoing space flight operations and research.
The NOAA SEC has a unique complement of people, experience, and resources that allows it to provide a high level of service to its space weather customers. There are no other sources, either domestic or foreign, that can provide this type of support. As the United States continues to expand its reliance on space-based assets such as GPS, cellular communications, and digital satellite technology, the importance of understanding the space weather environment becomes even more critical. The capability to monitor and forecast this environment should remain with the agency that has the mission and the proven expertise to respond to all of these customers.
I sincerely appreciate the forum that the Subcommittee provided today to highlight the importance of space weather forecasting, and I look forward to the opportunity to respond to your questions.