The Earth and Heliosphere - Brief

How do the Earth and Heliosphere respond?

Our planet is immersed in this seemingly invisible yet exotic and inherently dangerous environment. Above the protective cocoon of Earth’s lower atmosphere is a plasma soup composed of electrified and magnetized matter entwined with penetrating radiation and energetic particles. The Earth’s magnetic field interacts with the Sun’s outer atmosphere to create this extraordinary environment.

Our Sun’s explosive energy output forms an immense, complex magnetic fields structure. Hugely inflated by the solar wind, this colossal bubble of magnetism known as the heliosphere stretches far beyond the orbit of Pluto, from where it controls the entry of cosmic rays into the solar system. On its way through the Milky Way this extended atmosphere of the Sun affects all planetary bodies in the solar system. It is itself influenced by slowly changing interstellar conditions that in turn can affect Earth’s habitability. In fact, the Sun’s extended atmosphere drives some of the greatest changes in the near-Earth space environment affecting our magnetosphere, atmosphere, ionosphere, and potentially our climate.

Related missions:

*Sort missions by clicking Launch Date, A-Z, or PHASE column headers.

DIVISION	NAME	LAUNCH DATE	PHASE
Heliophysics	ACE Advanced Composition Explorer (ACE) observes particles of solar, interplanetary, interstellar, and galactic origins, spanning the energy range from solar wind ions to galactic cosmic ray nuclei. This mission is part of SMD's Explorers Program. This mission is part of SMD's ...	1997082708-27-1997	3Operating
Heliophysics	AIM Aeronomy of Ice in the Mesosphere (AIM) is a mission to determine the causes of the highest altitude clouds in the Earth's atmosphere. The number of clouds in the middle atmosphere (mesosphere) over the Earth's poles has been increasing over ...	2007042504-25-2007	3Operating
Heliophysics	CINDI/CNOFS The Coupled Ion-Neutral Dynamics Investigations (CINDI) is a mission to understand the dynamics of the Earth's ionosphere. CINDI will provide two instruments for the Communication/Navigation Outage Forecast System (C/NOFS) satellite, a project of the United States Air Force. This mission ...	2008041604-16-2008	3Operating
Heliophysics	Cluster-II Cluster is a European Space Agency program with major NASA involvement. The 4 Cluster spacecraft are providing a detailed three-dimensional map of the magnetosphere, with surprising results. This mission is part of SMD's Heliophysics Research program.	2000071607-16-2000	3Operating
Heliophysics	FAST Fast Auroral Snapshot Explorer (FAST) studies the detailed plasma physics of the Earth's auroral regions. Ground support campaigns coordinate satellite measurements with ground observations of the Aurora Borealis, commonly referred to as the Northern Lights. The science instruments on board ...	1996082108-21-1996	4Past
Heliophysics	Geotail The GEOTAIL mission is a collaborative project undertaken by the Japanese Institute of Space and Astronautical Science (ISAS) and NASA. Its primary objective is to study the tail of the Earth's magnetosphere. The information gathered is allowing scientists to model ...	1992072407-24-1992	3Operating
Heliophysics	Hinode (Solar-B) Hinode (formerly known as Solar-B) is a Japanese ISAS mission proposed as a follow-on to the highly successful Japan/US/UK Yohkoh (Solar-A) collaboration. The mission consists of a coordinated set of optical, EUV and X-ray instruments that are studying the interaction ...	2006092309-23-2006	3Operating
Heliophysics	IBEX IBEX will be the first mission designed to detect the edge of the Solar System. As the solar wind from the sun flows out beyond Pluto, it collides with the material between the stars, forming a shock front. This mission ...	2008101910-19-2008	3Operating
Heliophysics	MMS The Magnetospheric Multiscale mission will determine the small-scale basic plasma processes which transport, accelerate and energize plasmas in thin boundary and current layers – and which control the structure and dynamics of the Earth's magnetosphere. MMS will for the first ...	2014081408-14-2014	2Development
Heliophysics	Polar Polar is the second of two NASA spacecraft in the Global Geospace Science (GGS) initiative and part of the ISTP Project. GGS is designed to improve greatly the understanding of the flow of energy, mass and momentum in the solar-terrestrial ...	1996022402-24-1996	4Past
Heliophysics	RBSP The RBSP mission will provide scientific understanding, ideally to the point of predictability, of how populations of relativistic electrons and ions in space form and change in response to variable inputs of energy from the Sun.	2012051405-14-2012	2Development
Heliophysics	RHESSI Reuven Ramaty High Energy Solar Spectroscope Imager (RHESSI) studies solar flares in X-rays and gamma-rays. It explores the basic physics of particle acceleration and explosive energy release in these energetic events in the Sun's atmosphere. This is accomplished by imaging ...	2002020502-05-2002	3Operating
Heliophysics	SOHO Solar and Heliospheric Observatory (SOHO) is a solar observatory studying the structure, chemical composition, and dynamics of the solar interior. SOHO a joint venture of the European Space Agency and NASA. This mission is part of SMD's Heliophysics Research program.	1995120212-02-1995	3Operating
Heliophysics	Solar Dynamics Observatory (SDO) The Solar Dynamics Observatory (SDO) is the first mission and crown jewel in a fleet of NASA missions to study our sun. The mission is the cornerstone of a NASA science program called Living With a Star (LWS). The goal ...	2010021102-11-2010	3Operating
Heliophysics	Solar Probe Plus Solar Probe Plus will be a historic mission, flying into one of the last unexplored regions of the solar system, the Sun’s atmosphere or corona, for the first time. This mission is part of SMD's LWS Program.		1Under Study
Heliophysics	THEMIS Time History of Events and Macroscale Interactions during Substorms (THEMIS) is a study of the onset of magnetic storms within the tail of the Earth's magnetosphere. THEMIS will fly five microsatellite probes through different regions of the magnetosphere and observe ...	2007021702-17-2007	3Operating
Heliophysics	TRACE Transition Region and Coronal Explorer (TRACE) observes the effects of the emergence of magnetic flux from deep inside the Sun to the outer corona with high spatial and temporal resolution. This mission is part of SMD's Heliophysics Explorers program. This ...	1998040104-01-1998	4Past
Heliophysics	TWINS A & B TWINS will provide stereo imaging of the Earth's magnetosphere, the region surrounding the planet controlled by its magnetic field and containing the Van Allen radiation belts and other energetic charged particles. This mission is part of SMD's Explorers Program. This ...	2008031303-13-2008	3Operating
Heliophysics	Ulysses The Ulysses Mission is the first spacecraft to explore interplanetary space at high solar latitudes, orbiting the Sun nearly perpendicular to the plane in which the planets orbit. This mission is part of SMD's Heliophysics Research program.	1990100610-06-1990	4Past
Heliophysics	Wind Wind studies the solar wind and its impact on the near-Earth environment. This mission is part of SMD's Heliophysics Research program.	1994110111-01-1994	3Operating

SOLAR PROBE PLUS - Plunging a Probe into the Sun

Dwayne C. Brown
Headquarters, Washington     
202-358-1726 dwayne.c.brown@nasa.gov   

Sep. 02, 2010

 

RELEASE : 10-208

 

 

NASA Selects Investigations for First Mission to Encounter the Sun

 

 

WASHINGTON -- NASA has begun development of a mission to visit and study the sun closer than ever before. The unprecedented project, named Solar Probe Plus, is slated to launch no later than 2018.

The small car-sized spacecraft will plunge directly into the sun's atmosphere approximately four million miles from our star's surface. It will explore a region no other spacecraft ever has encountered. NASA has selected five science investigations that will unlock the sun's biggest mysteries.

"The experiments selected for Solar Probe Plus are specifically designed to solve two key questions of solar physics -- why is the sun's outer atmosphere so much hotter than the sun's visible surface and what propels the solar wind that affects Earth and our solar system? " said Dick Fisher, director of NASA's Heliophysics Division in Washington. "We've been struggling with these questions for decades and this mission should finally provide those answers."

As the spacecraft approaches the sun, its revolutionary carbon-composite heat shield must withstand temperatures exceeding 2550 degrees Fahrenheit and blasts of intense radiation. The spacecraft will have an up close and personal view of the sun enabling scientists to better understand, characterize and forecast the radiation environment for future space explorers.

NASA invited researchers in 2009 to submit science proposals. Thirteen were reviewed by a panel of NASA and outside scientists. The total dollar amount for the five selected investigations is approximately $180 million for preliminary analysis, design, development and tests.
The selected proposals are:

-- Solar Wind Electrons Alphas and Protons Investigation: principal investigator, Justin C. Kasper, Smithsonian Astrophysical Observatory in Cambridge, Mass.

This investigation will specifically count the most abundant particles in the solar wind -- electrons, protons and helium ions -- and measure their properties. The investigation also is designed to catch some of the particles for direct analysis.

-- Wide-field Imager: principal investigator, Russell Howard, Naval Research Laboratory in Washington. This telescope will make 3-D images of the sun's corona, or atmosphere. The experiment will also provide 3-D images of the solar wind and shocks as they approach and pass the spacecraft. This investigation complements instruments on the spacecraft providing direct measurements by imaging the plasma the other instruments sample.

-- Fields Experiment: principal investigator, Stuart Bale, University of California Space Sciences Laboratory in Berkeley, Calif. This investigation will make direct measurements of electric and magnetic fields, radio emissions, and shock waves that course through the sun's atmospheric plasma. The experiment also serves as a giant dust detector, registering voltage signatures when specks of space dust hit the spacecraft's antenna.

-- Integrated Science Investigation of the Sun: principal investigator, David McComas of the Southwest Research Institute in San Antonio.
This investigation consists of two instruments that will monitor electrons, protons and ions that are accelerated to high energies in the sun's atmosphere.

-- Heliospheric Origins with Solar Probe Plus: principal investigator, Marco Velli of NASA's Jet Propulsion Laboratory in Pasadena, Calif. Velli is the mission's observatory scientist, responsible for serving as a senior scientist on the science working group. He will provide an independent assessment of scientific performance and act as a community advocate for the mission.

"This project allows humanity's ingenuity to go where no spacecraft has ever gone before," said Lika Guhathakurta, Solar Probe Plus program scientist at NASA Headquarters, in Washington. "For the very first time, we'll be able to touch, taste and smell our sun."

The Solar Probe Plus mission is part of NASA's Living with a Star Program. The program is designed to understand aspects of the sun and Earth's space environment that affect life and society. The program is managed by NASA'S Goddard Space Flight Center in Greenbelt, Md., with oversight from NASA's Science Mission Directorate's Heliophysics Division. The Johns Hopkins University Applied Physics Laboratory in Laurel, Md., is responsible for formulating, implementing and operating the Solar Probe Mission.

For more information about the Solar Probe Plus mission, visit:

http://solarprobe.gsfc.nasa.gov/

For more information about the Living with a Star Program, visit: 

http://science.nasa.gov/about-us/smd-programs/living-with-a-star/

 

- end -

Space Clouds and the Icing of Earth

RELEASE : 05-066

 

 

NASA Study Suggests Giant Space Clouds Iced Earth

 

 

Eons ago, giant clouds in space may have led to global extinctions, according to two recent technical papers supported by NASA's Astrobiology Institute.

One paper outlines a rare scenario in which Earth iced over during snowball glaciations, after the solar system passed through dense space clouds. In a more likely scenario, less dense giant molecular clouds may have enabled charged particles to enter Earth's atmosphere, leading to destruction of much of the planet's protective ozone layer. This resulted in global extinctions, according to the second paper. Both recently appeared in the Geophysical Research Letters.

"Computer models show dramatic climate change can be caused by interstellar dust accumulating in Earth's atmosphere during the solar system's immersion into a dense space cloud," said Alex Pavlov, principal author of the two papers. He is a scientist at the University of Colorado, Boulder. The resulting dust layer hovering over the Earth would absorb and scatter solar radiation, yet allow heat to escape from the planet into space, causing runaway ice buildup and snowball glaciations.

"There are indications from 600 to 800 million years ago; at least two of four glaciations were snowball glaciations. The big mystery revolves around how they are triggered," Pavlov said. He concluded the snowball glaciations covered the entire Earth.

Pavlov said this hypothesis has to be tested by geologists. They would look at Earth's rocks to find layers that relate to the snowball glaciations to assess whether uranium 235 is present in higher amounts. It cannot be produced naturally on Earth or in the solar system, but it is constantly produced in space clouds by exploding stars called supernovae.

Sudden, small changes in the uranium 235/238-ratio in rock layers would be proof interstellar material is present that originated from supernovae. Collisions of the solar system with dense space clouds are rare, but according to Pavlov’s research, more frequent solar system collisions, with moderately dense space clouds, can be devastating. He outlined a complex series of events that would result in loss of much of Earth's protective ozone layer, if the solar system collided with a moderately dense space cloud.

The research outlined a scenario that begins as Earth passes through a moderately dense space cloud that cannot compress the outer edge of the sun's heliosphere into a region within the Earth's orbit. The heliosphere is the expanse that begins at the sun's surface and usually reaches far past the orbits of the planets. Because it remains beyond Earth's orbit, the heliosphere continues to deflect dust particles away from the planet.

However, because of the large flow of hydrogen from space clouds into the sun's heliosphere, the sun greatly increases its production of electrically charged cosmic rays from the hydrogen particles. This also increases the flow of cosmic rays towards Earth. Normally, Earth's magnetic field and ozone layer protect life from cosmic rays and the sun's dangerous ultraviolet radiation.

Moderately dense space clouds are huge, and the solar system could take as long as 500,000 years to cross one of them. Once in such a cloud, the Earth would be expected to undergo at least one magnetic reversal. During a reversal, electrically charged cosmic rays can enter Earth's atmosphere instead of being deflected by the planet's magnetic field.

Cosmic rays can fly into the atmosphere and break up nitrogen molecules to form nitrogen oxides. Nitrogen oxide catalysts would set off the destruction of as much as 40 percent of the protective ozone in the planet's upper atmosphere across the globe and destruction of about 80 percent of the ozone over the polar regions according to Pavlov.

For information about NASA and agency programs on the Internet, visit:http://www.nasa.gov

Collapse of the Earth's Upper Atmosphere

A Puzzling Collapse of Earth's Upper Atmosphere

July 15, 2010:  NASA-funded researchers are monitoring a big event in our planet's atmosphere. High above Earth's surface where the atmosphere meets space, a rarefied layer of gas called "the thermosphere" recently collapsed and now is rebounding again.

Layers of Earth's upper atmosphere. Credit: John Emmert/NRL. [larger image]

"This is the biggest contraction of the thermosphere in at least 43 years," says John Emmert of the Naval Research Lab, lead author of a paper announcing the finding in the June 19th issue of the Geophysical Research Letters (GRL). "It's a Space Age record."

The collapse happened during the deep solar minimum of 2008-2009—a fact which comes as little surprise to researchers. The thermosphere always cools and contracts when solar activity is low. In this case, however, the magnitude of the collapse was two to three times greater than low solar activity could explain.

"Something is going on that we do not understand," says Emmert.

The thermosphere ranges in altitude from 90 km to 600+ km. It is a realm of meteors, auroras and satellites, which skim through the thermosphere as they circle Earth. It is also where solar radiation makes first contact with our planet. The thermosphere intercepts extreme ultraviolet (EUV) photons from the sun before they can reach the ground. When solar activity is high, solar EUV warms the thermosphere, causing it to puff up like a marshmallow held over a camp fire. (This heating can raise temperatures as high as 1400 K—hence the name thermosphere.) When solar activity is low, the opposite happens.

Lately, solar activity has been very low. In 2008 and 2009, the sun plunged into a century-class solar minimum. Sunspots were scarce, solar flares almost non-existent, and solar EUV radiation was at a low ebb. Researchers immediately turned their attention to the thermosphere to see what would happen.

These plots show how the density of the thermosphere (at a fiducial height of 400 km) has waxed and waned during the past four solar cycles. Frames (a) and (c) are density; frame (b) is the sun's radio intensity at a wavelength of 10.7 cm, a key indicator of solar activity. Note the yellow circled region. In 2008 and 2009, the density of the thermosphere was 28% lower than expectations set by previous solar minima. Credit: Emmert et al. (2010), Geophys. Res. Lett., 37, L12102.

How do you know what's happening all the way up in the thermosphere?

Emmert uses a clever technique: Because satellites feel aerodynamic drag when they move through the thermosphere, it is possible to monitor conditions there by watching satellites decay. He analyzed the decay rates of more than 5000 satellites ranging in altitude between 200 and 600 km and ranging in time between 1967 and 2010. This provided a unique space-time sampling of thermospheric density, temperature, and pressure covering almost the entire Space Age. In this way he discovered that the thermospheric collapse of 2008-2009 was not only bigger than any previous collapse, but also bigger than the sun alone could explain.

One possible explanation is carbon dioxide (CO₂).

An NCAR video shows how carbon dioxide warms the lower atmosphere, but cools the upper atmosphere. [more]

When carbon dioxide gets into the thermosphere, it acts as a coolant, shedding heat via infrared radiation. It is widely-known that CO₂ levels have been increasing in Earth's atmosphere. Extra CO₂ in the thermosphere could have magnified the cooling action of solar minimum.

"But the numbers don't quite add up," says Emmert. "Even when we take CO₂ into account using our best understanding of how it operates as a coolant, we cannot fully explain the thermosphere's collapse."

According to Emmert and colleagues, low solar EUV accounts for about 30% of the collapse. Extra CO₂ accounts for at least another 10%. That leaves as much as 60% unaccounted for.

In their GRL paper, the authors acknowledge that the situation is complicated. There's more to it than just solar EUV and terrestrial CO₂. For instance, trends in global climate could alter the composition of the thermosphere, changing its thermal properties and the way it responds to external stimuli. The overall sensitivity of the thermosphere to solar radiation could actually be increasing.

"The density anomalies," they wrote, "may signify that an as-yet-unidentified climatological tipping point involving energy balance and chemistry feedbacks has been reached."

Or not.

Important clues may be found in the way the thermosphere rebounds. Solar minimum is now coming to an end, EUV radiation is on the rise, and the thermosphere is puffing up again. Exactly how the recovery proceeds could unravel the contributions of solar vs. terrestrial sources.

"We will continue to monitor the situation," says Emmert.