Space weather refers to variations in the space environment between the sun and Earth (and throughout the solar system) that can affect technologies in space and on Earth. Space weather can disrupt the technology that forms the backbone of country’s economic vitality and national security, including satellite and airline operations, communications networks, navigation systems, and the electric power grid, says National Space Weather Strategy product of the National Science and Technology council.
Active events on the sun can lead to interference in the propagation of radio signals. Space weather events, in the form of solar flares, solar energetic particles, and geomagnetic disturbances, occur regularly, some with measurable effects on critical infrastructure systems and technologies, such as the Global Positioning System (GPS), satellite operations and communication, aviation, and the electrical power grid.
Space weather also gets degraded on event of High Altitude Nuclear Detonation or Explosion (HAND or HANE). HANE produce energetic gamma rays (about 5% of yield) move at the speed of light and interact (Compton Effect) with neutral particles in the upper atmosphere producing energetic electrons and ions. These electrons and charged particles gyrate and get trapped around the earth’s magnetic field. Energetic radiation belt produced by HAND is proved to be responsible in shortening operational life time of LEO satellites. Even small HANDs (~10-20 Kt at 125-300 Km altitude) is expected to raise peak radiation flux about 3-4 orders of magnitude in the inner radiation belts and lead to the loss of 90% LEO satellites within a month.
The timely forecasting of space weather is of great importance for the aviation industry and the protection of a number of ground-based technical systems, as well as for manned space flights and the launching of scientific and commercial satellites.
Countries are launching ground and space weather sensors for real time monitoring and prediction of space weather events and also hardening their systems from space weather events.
Space Weather Sensors
Scientists utilize a variety of ground- and space-based sensors and imaging systems to view activity at various depths in the solar atmosphere. Telescopes are used to detect visible light, ultraviolet light, gamma rays, and X rays. They use receivers and transmitters that detect the radio shock waves created when a CME crashes into the solar wind and produces a shock wave. Particle detectors to count ions and electrons, magnetometers record changes in magnetic fields, and UV and visible cameras observe auroral patterns above the Earth.
NASA operates a system observatory of Heliophysics missions, utilizing the entire fleet of solar, heliospheric, and geospace spacecraft to discover the processes at work throughout the space environment.
Beyond NASA, interagency coordination in space weather activities has been formalized through the Committee on Space Weather, which is hosted by the Office of the Federal Coordinator for Meteorology. This multiagency organization is co-chaired by representatives from NASA, NOAA, DoD, and NSF and functions as a steering group responsible for tracking the progress of the National Space Weather Program.
A Japanese spacecraft designed to help scientists better understand the radiation environment of near-Earth space has made it to orbit. The Exploration of energization and Radiation in Geospace satellite, or ERG, lifted off atop an Epsilon rocket from Uchinoura Space Center in southern Japan on Dec. 20. The 780-lb. (355 kilograms) ERG satellite has a highly elliptical orbit, getting as close to Earth as 215 miles (350 kilometers) and as far away as 18,640 miles (30,000 km). This path will take the through the Van Allen radiation belts, where the planet’s magnetic field has trapped huge numbers of fast-moving electrons and other particles.
ERG’s purpose “is to reveal how these high-energy electrons are accelerated and created, and how space storms develop,” JAXA officials wrote in an ERG fact sheet. “ERG will make a comprehensive observation of the electrons and ions near the equatorial plane in geospace, which is thought to be the area where the acceleration of such electrons is occurring.”The satellite will use nine different instruments to do this work, over the course of a mission designed to last at least one year.
China plan Space weather sensors
China is striving to send a group of new satellites into orbit around 2020, as part of the country’s fast-expanding space science program, a national science official said at a space conference. The satellites include a Sino-European joint mission known as “SMILE,” which will focus on the interaction between the solar wind and the Earth magnetosphere, according to Wang Chi, director of the National Space Science Center under the Chinese Academy of Sciences.
The Solar wind Magnetosphere Ionosphere Link Explorer, or SMILE, will also help study magnetospheric substorms, so as to further our understanding of the impact of solar activities on Earth’s environment and space weather, Wang said.
The satellites also include the Advanced Space-borne Solar Observatory (ASO-S) and the Gravitational Wave Electromagnetic Counterpart All-sky Monitor (GECAM). The former will help scientists understand the causality among magnetic fields, flares, and coronal mass ejections, and the latter is aimed at searching for electromagnetic signals associated with gravitational waves.
The Magnetosphere-Ionosphere-Thermosphere Coupling Exploration (MIT),is also in the satellite group. MIT aims at investigating the origin of upflow ions and their acceleration mechanism and discovering the key mechanism for the magnetosphere, ionosphere, and thermosphere coupling.
China is building world’s most powerful laser radar to study Earth’s solar shield
China has started building the world’s most powerful laser radar designed to study the physics of the Earth’s high atmosphere, according to state media reports and scientists informed of the project. It is described as having a detection range of 1,000km (600 miles) – 10 times that of existing lasers – and will be used to study atmospheric particles that form the planet’s first line of defence against hostile elements from outer space such as cosmic rays and solar winds. “The large-calibre laser radar array will achieve the first detection of atmospheric density of up to 1,000km in human history,” said a statement posted on the website of the Chinese Academy of Sciences on Tuesday, a day after the launch of the project.
The facility, to be built on a site that remains classified, is expected to be up and running within four years and will form part of an ambitious project to reduce the risk from abnormal solar activities. The radar will use a high-energy laser beam that can pierce through clouds, bypass the International Space Station and reach the outskirts of the atmosphere, beyond the orbiting height of most Earth observation satellites.
There, the air becomes so thin that scientists will be able to count the number of gas atoms found within a radius of several metres. These high-altitude observations could greatly expand our knowledge of a part of the atmosphere that has been little studied because the distances involved mean no one has been able to make direct observations from the ground.
According to publicly available information, the facility will use several large optical telescopes to pick up the faint signals reflected by the high-altitude atoms when the laser is fired at them. The project is part of the Meridian Space Weather Monitoring Project, an ambitious programme that started in 2008 to build one of the largest, most advanced observation networks on Earth to monitor and forecast solar activities. By 2025 Meridian stations containing some of the world’s most powerful radar systems will be established across the world – with facilities in Arctic and Antarctic, South China Sea, the Gobi desert, the Middle East, Central Asia and South America.
The purpose of the Meridian project, according to the Chinese government, is to reduce the risk abnormal solar activities pose to a wide range of Chinese assets including super-high voltage power grids, wireless communication, satellite constellations, space stations or even a future base on the Moon
Professor Li Yuqiang, a researcher at the Yunnan Observatories in Kunming, whose team has measured the distance between the Earth and the Moon by shooting lasers at a reflector placed on the lunar surface during the US Apollo 15 mission, said detecting atom-sized targets on the fringes of the atmosphere posed many technical challenges.
“The number of photons [particles of light] reflected by the sparse gas particles will be very small. Even if they can be picked up by large telescopes on the ground, the analysis will require some very good algorithms to separate the useful signals from the noise,” Li said.
Small satellites the solution for space weather monitoring
With key space weather satellites expected to fail before U.S. and European agencies launch replacements, “small satellites may be the only way of averting a bleak future,” said Daniel Baker, director of the University of Colorado’s Laboratory for Atmospheric and Space Physics.
Many of the instruments the U.S. relies on to monitor solar flares, coronal mass ejections and other phenomena that pose a threat to satellites in orbit and technology on the ground are well beyond their anticipated life spans. The National Oceanic and Atmospheric Administration (NOAA) is sending new instruments into orbit on its latest generation of geostationary weather satellites but other updates to the space weather constellation are likely to fly years after current instruments fail. That’s prompting government, industry and academic experts to consider how cubesats and small satellites could help.
“Most of the measurements we’re making for operational space weather certainly can be done with smaller satellites,” said Douglas Biesecker, NOAA National Space Weather Prediction Center’s research and customer requirements section lead. “For certain problems, you want a bunch of distributed satellites.”
To date, large government satellites have been packed with multiple state-of-the-art sensors to provide exquisite detail of the space weather environment at a single point in space. While cubesats are not likely to replace the large observatories at the Earth-Sun L1 Lagrange point anytime soon, a constellation of the miniature spacecraft orbiting Earth at all longitudes and various altitudes would be helpful in monitoring energetic particles and magnetic fields, said Biesecker, a solar physicist and program scientist for NOAA’s Deep Space Climate Observatory, a 570-kilogram satellite launched in 2015 to track solar wind from L1, a gravitationally stable perch 1.5 million kilometers from Earth.
NOAA’s New Satellite, DSCOVR, Monitors The Space Weather
The National Oceanic and Atmospheric Association (NOAA) newest satellite called DSCOVR could detect space weather. According to NOAA, the new satellite is located approximately 1 million miles from the Earth’s surface. It sits at a point called as Lagrange point 1 or L1, wherein the gravitational forces between Earth and the sun are in balance.
The space weather sensors of DSCOVR include the Faraday cup plasma sensor. This measures the density, velocity and the temperature of the solar wind. It also has magnetometer that gauges the strength and direction of the solar wind magnetic field. These can deliver information to the NOAA’s Space Weather Prediction Center (SWPC) about storm warnings up to one hour in advance. DSCOVR also aims to maintain the nation’s real-time solar wind monitoring capabilities.
NASA small satellite tech for space weather monitoring
NASA has selected two photonics-based proposals to develop new technologies for small satellite applications, ultimately intended to improve science observations in deep space and to help the agency develop better models for predicting “space weather”.
Funded under NASA’s Heliophysics Solar Terrestrial Probes program, which is managed by the Goddard Space Flight Center, the two technologies involved are optical communications for CubeSats, and a giant solar sail for propulsion.
the “solar cruiser” project, managed out of the Marshall Space Flight Center in Huntsville, Alabama, will aim to demonstrate the viability of an 18,000-square-foot solar sail as a propulsion system. “Such a system could provide views of the Sun not easily accessible with current technology,” NASA noted.
The second part of this project would involve a coronagraph instrument to enable simultaneous measurements of the Sun’s magnetic field structure and velocity of coronal mass ejections (CMEs). CMEs send colossal amounts of energy, particles, and radiation into space that can set off space weather storms capable of interfering with key terrestrial infrastructure, including electrical grids and communications networks.
“Improving data-gathering technology in this area is particularly useful for advance warning systems for at-risk infrastructure on Earth,” said NASA, with Les Johnson selected as principal investigator. At the end of the nine-month study period, one of the proposals will be selected to progress to launch, as a secondary payload with NASA’s Interstellar Mapping and Acceleration Probe. The launch is currently scheduled for October 2024.
Air Force Seeks Info on Space Weather Sensor
The U.S. Air Force has issued a request for information for a space environment sensor that would operate as a secondary payload aboard a proposed next-generation weather satellite.
In a June 16 posting on the Federal Business Opportunities website, the service said it was seeking industry feedback on likely capabilities, costs and risks on a sensor to measure energetic charged particles aboard the Weather Satellite Follow-on program. Responses are due July 16.
The Weather Satellite Follow-on, the Air Force’s designated replacement for its Defense Meteorological Satellite System, will consist of a single satellite carrying two or three instruments that would launch into sun-synchronous orbit in 2021 or 2022. The program is expected to cost about $856 million, according to Air Force budget documents.
The Air Force will rely on the next-generation satellite to fill three main data requirements: ocean-surface wind speed and direction, tropical cyclone intensity, and information on charged particles in space with the potential to affect low-orbiting satellites. The first two measurements could be taken using the same microwave payload, according to Air Force documents. The service issued a request for information for that instrument in February.
The sensor described in the June 16 request for information would measure about 13 centimeters by 20 centimeters, weigh less than 4 kilograms and have a design life of about 12 years.
New Atmosphere Wind/Temperature Sensor to Improve Space Weather Prediction
Global wind and temperature measurements in the lower thermosphere (100-150 km above Earth) are the two most important variables needed to accurately predict space weather and climate change. An innovative technique is being developed jointly by the Johns Hopkins University Applied Physics Laboratory, GSFC, and JPL to make these measurements using the atomic oxygen emission at 2.06 THz (145 μm).
A new sensor, called the TeraHertz Limb Sounder (TLS), will make these critical measurements under a wide range of observation conditions (e.g., day and night, with and without aurora present) from a low Earth orbit. Not only will TLS measurements enable scientists to study neutral atmosphere interactions with the ionosphere and magnetosphere above, they will improve our fundamental understanding of the mechanisms and effects in Earth’s upper atmosphere and other planetary and stellar atmospheres.
The data will also help researchers understand how the upper atmosphere is affected by solar variability (i.e., radiation, magnetized solar winds, and energetic particles) and lower-atmospheric disturbances—critical geophysical processes that influence numerous space weather phenomena that present hazards to spacecraft, humans in space, and technological infrastructure on the ground.
The TLS instrument is enabled by a high-sensitivity gallium arsenide (GaAs)-diode-based heterodyne receiver that operates at room temperature. In 2016, the team developed the high-frequency Schottky diode , which mixes the incoming signal from 2.06 THz down to an intermediate frequency band to measure spectral emission features from atomic oxygen in the atmosphere. This advanced mixer technology can be used to build compact, low-mass and low-power instruments for NASA’s small satellite missions.
TLS development will mature and optimize a low-noise, high-sensitivity THz receiver to advance Heliophysics science in future space weather missions with reduced cost and schedule risks.