Space Physics is beginning a voyage of discovery to explore and characterize Earth's space environment.
Space Physics is the study of the heliosphere (the sphere of influence of the Sun) as one system. It seeks to explore and understand the dynamics of the Sun and the interactions of the heliosphere with Earth, other planetary bodies, and the interstellar medium.
NASA contributes to the creation of new scientific knowledge by
exploring the Solar System and the Universe beyond and by studying the space
environment and its effects on biological and physical processes... The purpose
of the Scientific Research Enterprise is to seek answers to fundamental
questions, such as:
How are the conditions for life on Earth maintained?
How does the solar output vary? How does the Earth's magnetic field trap
radiation and protect the planet?... What knowledge from space can improve the
quality of life on Earth?...
NASA Strategic Plan, 1994
The Sun
Its sources of energy and variability, its influence on Earth, and its role as the dominant source of energy in the solar system.
Solar-Terrestrial and Solar-Planetary Relations
The influence of energetic solar radiation and the solar wind on the magnetospheres and upper atmospheres of the Earth and the other planets.
The Heliosphere
Its nature, dynamics, and contents, extending from the Sun to the outer frontiers of the solar system.
Cosmic Rays
The origin, acceleration, and propagation of solar and galactic cosmic rays in the heliosphere and galaxy.
...to explore and understand the dynamics of the Sun and
its outpouring over the planets to form the heliosphere
Solar Connections is a program to observe and interpret the variable radiations in the Earth's space environment. The Sun, its atmosphere and heliosphere, and the Earth's magnetosphere and atmosphere are coupled by physical processes that are only partially known. These processes will be explored to achieve major advances in understanding.
Solar radiation includes magnetized plasma, high-energy, electrically charged particles, and electromagnetic emissions that are absorbed in and above the Earth's atmosphere. The magnetosphere and ionosphere affect this radiation in complex and subtle ways, with important terrestrial consequences.
This radiation is just a tiny fraction (1%) of total solar radiation but can have hugely disruptive effects on all links of the chain. In addition, this 1% acts as a messenger, carrying information that enables scientists to under-stand the processes that cause this radiation.
Solar Connections focuses on the solar atmosphere and flares, global magnetospheric structure and dynamics, and upper atmospheric structure and energetics, and the coupling among them.
Solar Connections examines the frontiers at both the very inner and outer fringes of our solar system and will explore in-situ deep in the solar atmosphere, closer to the Sun than ever before.
Upper Left: The High-Energy Solar Imager will study solar flares in X- rays and gamma rays
Lower Left: The Solar Probe will study the inner corona close to the Sun
Upper Right: A simulation of the plasmasphere to be studied by the Magnetosphere Imager
Lower Right: Phenomena that may trigger high-altitude noctilucent clouds will be investigated by TIMED
Relevance to Society
Solar Connections' contribution to society:
* Space environment effects or "space weather"
* Global change
* Education and scientific advancement
* Technology transfer
* International collaboration
Space Weather: Space assets (worth $110B) provide weather forecasts, television, telephone, navigation, and other important services. The Sun's variable interaction with the magnetosphere, ionosphere, and upper atmosphere can create a potentially damaging environment for those space assets. Solar Connections will provide a firmer foundation for more reliable "space weather" prediction. A casualty of "space weather," ANIK-E2, a communications satellite, recently failed after being bombarded by high-energy electrons triggered by the Sun.
Global Change: The program will help clarify the relative contributions of natural processes and human activities to global change and can provide answers to important questions in global climate. Changes in the thermosphere also provide an extremely sensitive test of more subtle changes in the lower atmosphere, as harbingers of global change.
Education: Solar Connections will produce images of the vast, dynamic space environment around Earth and the Sun and enhance general knowledge of these phenomena. The program will have a strong, central educational component for all students.
Technology: Solar Connections will use and develop new technologies such as high-density data storage; new image-processing techniques; radiation-hardened microprocessors; lightweight fiber composites and optical coatings; ultra-high temperature resistant materials; new cooling technology; and new ways of taking X-ray pictures.
International: Solar Connections is a cooperative international program, in particular in a joint effort with Russia to study the Sun. A comprehensive international ground-based effort will provide collaborative data.
Hallmarks of Success
When Solar Connections is complete, we will have achieved:
* The first detailed understanding of the effect of solar variations on physical and chemical processes acting in the upper atmosphere.
* Significantly improved understanding of solar flares from studying the highly energetic particle acceleration processes in the solar atmosphere.
* Increased understanding of magnetospheric responses to solar and interplanetary disturbance using the first-ever global images of the magnetospheric plasmas.
* Understanding of the heating and acceleration of the solar wind using direct in-situ observations.
* An enhanced scientific basis for understanding practical problems such as space weather prediction and global change.
* Visually exciting images of space phenomena around the Earth and close to the Sun to inspire public interest and promote science education.
* New technology for US industry.
We can view the solar connection within the solar system
as a chain of individual links:
The Sun's influence on the heliosphere and planetary bodies is accomplished through two kinds of radiation:
The solar wind, comprised of hot, high-speed, electrically charged atomic particles, flows from the Sun to fill the heliosphere. This radiation is threaded by the faint magnetic field that originates at the Sun and extends throughout the heliosphere in giant spiral arcs. The solar wind affects the shape and dynamical behavior of the Earth's magnetic field, and determines the dimensions of the heliosphere itself.
Electromagnetic radiation, the second component, spans all wavelengths from radio waves to gamma rays. This radiation heats the planetary bodies and ionizes the upper layers of their atmospheres.
The individual links connecting solar radiation to the heliosphere and planetary bodies start at the nuclear furnace at the center of the Sun and extend through the Sun's convection zone, through the layers of the solar atmosphere (chromosphere and corona), into interplanetary space, and on to the magnetospheres, ionospheres, and atmospheres of the planets. They couple the Sun's energy to each planet in the solar system.
Solar Connections: A Closer Look
To understand the end-to-end connection of the Sun to the Earth, we must understand each link in the chain. The purpose of Solar Connections is to conduct an orderly, systematic study, that will give us the scientific basis to understand the whole chain.
When we examine the Solar Connection chain closely, we find an intricate picture. At the Sun, energy is released from the nuclear furnace at the Sun's core. This energy heats and drives processes in the Sun's atmosphere that result in explosive energy releases, such as solar flares and coronal mass ejections (CMEs).
The hot, gusty, electrically charged, coronal gas (the solar wind) flows at speeds of 200 to 1000 km/sec and carries with it a magnetic field rooted in the Sun. The solar wind, and even hotter, faster charged particles accelerated in flares and CMEs, encounter the Earth's magnetosphere (and those of other planets). This high-speed flow of plasma couples to the magnetosphere through a variety of paths at both polar and equatorial latitudes and in the extended downstream magnetotail.
The magnetosphere provides conduits through which millions of megawatts of energy carried via corpuscular radiation are eventually dumped into the ionosphere and upper atmosphere. This is the dominant energy input to the upper atmosphere. The solar wind also causes changes in the intensity of galactic cosmic rays at Earth, which are a major factor governing the electrical conductivity of the atmosphere.
Electromagnetic radiation, especially a steady bath of ultraviolet (UV) radiation and variable levels of X-ray, gamma ray, and UV radiation from solar active regions, illuminates and affects all layers of the atmosphere directly.
...a program to observe and interpret the variable radiations in the Earth's space
environment and explain the influence of the Sun on the Earth and the Heliosphere
Solar Connections: The Near-Term Program
The Near-Term Program Focuses on the Weakest Links in Our Knowledge of the Solar Connections Chain
The most effective use of resources requires that science programs become more selective and efficient, focus on questions of immediate impact on NASA's space science objectives, and have a strong component addressing societal needs. The near-term program in Solar Connections focuses on Sun-Earth relationships.
We propose an integrated, balanced flight program that builds on existing spacecraft, together with three new, small, high-technology spacecraft called Solar-Terrestrial Probes and an innovative Solar Probe mission undertaken jointly with Russia. The program will make a concerted attack on the problem of solar activity and how it impacts the terrestrial environment, thereby focusing on the weakest links in the solar connections chain.
The Solar-Terrestrial Probes are new, low-cost imaging spacecraft that will study the mesosphere-thermosphere, high-energy aspects of solar flares, and the magnetosphere, in a coordinated, phased effort. Each component of this program has evolved, scientifically and
technologically, from refined studies involving all of the space physics community and are considered the best missions for addressing the most important unanswered questions in the Solar Connections chain. The Solar-Terrestrial Probes are TIMED (Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics), HESI (High-Energy Solar Imager), and MI (Magnetospheric Imager).
Solar Probe, a mission to send instruments closer to the surface of the Sun than ever before attempted, is a US-Russian space cooperation feature of Sun-Earth Connections, and is an integral part of the US-Russia program called Fire and Ice.
Upper Left: The High-Energy Solar Imager will study solar flares in X- rays and gamma rays
Lower Left: The Solar Probe will study the inner corona close to the Sun
Upper Right: A simulation of the plasmasphere to be studied by the Magnetosphere Imager
Lower Right: Phenomena that may trigger high-altitude noctilucent clouds will be investigated by TIMED
Solar Connections: The Program
Strengthening the Weakest Links in the Solar Connections Chain:
Solar Connections will allow us to:
* Understand the flow of energy through the complex transition region between space and the lower atmosphere, using remote sensing and imaging techniques, with the Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) spacecraft.
* Obtain images and spectra of solar flare explosions on the Sun with the High Energy Solar Imager (HESI), to pinpoint the location and dynamics of high-energy processes.
* Obtain the first images of the complete magnetosphere using the Magnetosphere Imager (MI), to determine the shape of the magnetosphere and how it changes in response to interplanetary disturbances.
* Obtain the first direct in-situ measurements in the Sun's corona and unprecedented views of the Sun from the Solar Probe. The objective is to understand the mechanisms that heat the extended solar atmosphere and accelerate the solar wind.
Thermosphere,
Ionosphere, Mesosphere
Energetics
and Dynamics (TIMED)
Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED)
Science at the Crossroads of the Earth's Atmosphere
TIMED will provide a benchmark for future studies of natural and human-induced changes to the Earth's atmosphere, providing an avenue for early warning of global change.
TIMED, a small remote sensing and imaging spacecraft, will achieve quantitative understanding of the energetics and dynamics of the Mesosphere and Lower Thermosphere-Ionosphere (MLTI) between ~50 and 200 km. The MLTI is a transition region in which many important processes are known to change dramatically, yet there are only sketchy and incomplete measurements of the region. This is where temperature variations, which increase dramatically with altitude, are largest, and where atmospheric motions are dominated by poorly understood gravity waves and tides.
When the mission is complete, it will have:
* Performed the first focused exploration of the MLTI region - a major link in the solar-terrestrial chain.
* Traced the flow of energy and momentum from the lower into the upper atmosphere.
* Quantified the dramatic influences of the Sun and outer space on the Earth's middle and upper atmosphere, increasing our ability to predict space weather.
* Examined the major energy sources, transport processes and energy sinks in the MLTI, and applied this information to define the channels by which energy enters into, travels through, and is lost from the region.
* Supplied knowledge of the upper atmospheric circulation pattern and its role in the transport of chemicals important in ozone chemistry.
Capturing the Origins of Solar Flares with HESI
The High-Energy Solar Imager (HESI)
Imaging and Profiling Solar Flares, the Largest and Most Powerful Explosions in the Solar System
Solar flares are the largest and most powerful explosions in the solar system. The emissions from solar flares and CMEs and the particles and shock waves that often accompany them can profoundly affect the space environment around the Earth, are dangerous to astronauts and to spacecraft, and can cause significant effects in the Earth's atmosphere and at the surface. Scientists have learned much about solar flares from space- and ground-based observations over the years, but two basic questions remain unanswered.
* How is a flare's tremendous energy released so rapidly?
* How are so many electrons and protons accelerated to such high energies?
The answers are thought to lie with the hard X-rays and gamma rays emitted by the accelerated particles themselves. HESI's innovative solar telescope combines, for the first time, high-resolution imaging in hard X-rays and gamma rays with high-resolution spectroscopy, to obtain a detailed energy spectrum at each point of the image.
HESI will lead to improved understanding and more reliable predictive capabilities of intense flares and their most dangerous consequences. HESI will also provide unique information on the fundamental processes of explosive particle acceleration and plasma heating that occur at many sites throughout the universe, including in pulsars, quasars, and around black holes.
The best time to study solar flares is at a peak of the 11-year cycle of solar activity, next expected in the year 2000. HESI should be in orbit by then to catch the most flares during its 1-to-3-year lifetime.
The broadband X-ray images of the Sun shown here were taken with instruments on the joint Japanese/US Yohkoh mission during a solar flare in January 1992.
Imaging the Magnetosphere with MI
MI will provide the first moving images of changes in Earth's magnetosphere.
MI will use innovative techniques to provide the first moving images of changes in Earth's magnetosphere as it responds to highly variable injections of plasma from the Sun. MI will observe emissions of energetic neutral atoms and extreme and far ultraviolet photons to produce simultaneous images of various components of the magnetosphere: the ring current, the inner plasma sheet, the plasmasphere, aurora, and the geocorona. This will enable researchers to visualize and identify the strength and nature of the connections among these parts of the magnetosphere, especially as they change during geomagnetic storms and fluctuations in the speed and force of the solar wind. The shape of major features will be available to compare with theoretical models and with shapes inferred from in-situ measurements.
The global images obtained will be related to local observations in order to:
* learn how local processes combine to form the whole (synergism)
* provide a global framework for local observations (context)
* identify new processes (discovery)
Solar Probe: Deep into the Corona
Solar Probe
Solar Probe Will be the First Spacecraft to Fly Through the Atmosphere of Our Sun
The Solar Probe, a unique high-technology dual spacecraft mission to be implemented in cooperation with the Russians, will venture deep into the solar corona, the Sun's outer atmosphere - far closer to the Sun than any other spacecraft has previously ventured. It will demonstrate technologies for imaging, and taking in-situ and remote measurements at 3 solar radii (Rs) above solar surface, where radiation temperatures exceed 2000 K.
Solar Probe is designed to answer long-standing fundamental questions:
* What heats the extended solar corona and accelerates the solar wind?
* From where in the corona do the different types of solar wind originate?
* What roles do turbulence and waves play in the coronal heating process?
* What are the mechanisms that accelerate, store and transport high energy particles throughout the corona?
Our Sun is the only star we can measure in situ. Solar Probe will relate remotely observed solar phenomena to actual physical processes occurring in the solar atmosphere and corona. This will offer unique access to processes that are important in many other significant but inaccessible stars throughout the Universe.
Integrated Data to Understand Coupling of Critical Links
Integration Through Science Data Systems
[TO BE REWORKED BY JOE ALEXANDER]
The individual imaging missions
of Solar Connections provide multi-dimensional views of the links in the solar
connections chain not yet addressed by previous observations. The challenge of
Solar Connections will be to both examine the individual links in the chain and
to understand how the links are coupled.
There are two key elements in the strategy to meet this challenge:
* An integrated sequence of focused missions directed at understanding the critical links in the solar connections chain
* Use of rapidly advancing information system technologies to ensure that data from the individual mission elements is rapidly accessed and integrated by a broad research community.
This data base will form a facility-like "observatory" of the physics and dynamical flows of the entire solar-terrestrial chain, whose value as a whole can greatly exceed the sum of its individual parts.
A new generation of information systems is in place to serve ongoing and new missions through the International Solar Terrestrial Physics (ISTP) Program. These systems already provide data standards and portable software to capitalize on the continuing massive advances in information and communications technologies. The Solar Connections data strategy will build on these capabilities to enhance the ability of distributed systems to provide full public access to research data.
Imaging Science for the Visual Generation
The relationship between the Sun and the Earth is an important educational theme in space physics. The topic is featured in high school science curricula, and provides an excellent focus for teaching a wide range of math and science concepts.
Solar Connections offers an exciting opportunity to build on this effort. The connections between the ultraviolet and extreme ultraviolet output of the Sun and its impact on the upper atmosphere of the Earth resonate with topical public concern over ozone depletion and global change. This awareness is an ideal foundation on which to build students' knowledge of the physics and chemistry of the least-explored region of the Earth's atmosphere and, ultimately, to increase their understanding of the relative importance of natural and human impacts on climate.
Solar Connections will:
* Allow students to see unique images of a variety of phenomena in "electric space" and the impact that this violent, charged space environment around the Earth has on life on the ground. Vivid, first-time images taken close to the Sun will dramatize the powerful processes that bombard the Earth.
* Solar Connections will use new tools to give students access to this new world - over the Internet, through CD-ROMs, through hands-on activity with spacecraft, and through science outreach.
* The program will use new management modes - investigator-led, through partnerships with industry, NASA, and academia - to open up the techniques and challenges of space investigation to many curious young minds.
Solar Connections also encompasses a new group of young scientists keen to reach out and spread their own excitement beyond the scientific community.
A strong program of educational outreach will thus be a central feature of Solar Connections.
Strawman Program Implementation
New Approach to Program Implementation
The Solar Connections program will follow an efficient and cost-effective development path, according to the following principles:
* Highest-priority, focused science objectives that relate directly to understanding the connections between and among the different regions of the solar-terrestrial environment.
* Short development period - averaging some 36 months - with combined design and development phases under a single team.
* Small, integrated mission teams generally consisting of university researchers, industrial firms with flight hardware experience, and NASA, with one lead investigator.
* Innovative practices such as vertically integrated development, integration, launch services and operations, and fees based on performance in orbit.
* Cost-controlled missions, with specified design-to-cost caps and agreed-upon descope plans if cost growth occurs.
* Instruments built to cost with design beginning prior to spacecraft design.
* "Skunk works" project atmosphere that minimizes oversight, review, and documentation.
* Realistic trade-offs among cost, performance requirements, and risk.
* An intelligent mix of proven and new technology.
* Strong commitment to education and developing increased public awareness of space science.
Solar Connections
What? Solar Connections is an integrated program to observe and interpret the variable radiations in the Earth's solar system environment so as to understand the influence of the Sun on the Earth and the heliosphere.
Why? To understand fundamentally important aspects of our space environment - the variable Sun, its radiations and space plasmas, and their effects on the Earth's atmosphere.
Summary
Benefits:
* Improve the scientific understanding of the effects of solar variations on the Earth
* Identify and quantify solar inputs to global change
* Improve understanding of causes of space environmental changes
* Extend fundamental laboratory plasma science via observation of space plasmas
* Provide remote and in-situ observations of astrophysically important plasma processes
* Mitigate the hazards to humans and technology of the space environment
* Extend public understanding of space science
* Demonstrate advanced technologies
Hallmarks of Success:
* Solar Probe: Fly through the atmosphere of our Sun for the first time.
* MI: Take the first picture and movie of Earth's magnetosphere and its electrical storms.
* HESI: Capture the solar flare signals that revel the causes and effects of the largest explosions in the solar system.
* TIMED: Examine the crossroads in Earth's atmosphere through which invisible radiations from the Sun determine how our atmosphere behaves.
Technical and Programmatic Progress:
* Small spacecraft; sharply focused objectives
* Streamlined procurements; rapid development
* Advanced, often miniaturized instruments
* Enhanced scientist involvement in program management and development
* Scheduled to take advantage of next solar cycle