Laboratory for Atmospheric and Space Physics

Boulder City, CO, United States

Laboratory for Atmospheric and Space Physics

Boulder City, CO, United States
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News Article | April 17, 2017
Site: www.newscientist.com

It vanished into thin air. Around 90 per cent of the Red Planet’s atmosphere was probably lost to space over just a few hundred million years, according to a key measurement from NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft. Today Mars is a freezing, arid desert with an atmosphere 1 per cent as dense as Earth’s and its water mostly locked up in polar ice caps. But most planetary scientists think it was not always so. Certain Mars soils contain minerals that on Earth are produced in the presence of water, and some Martian features seem to point towards ancient lakebeds and even fast-flowing rivers. To have retained this liquid water, the planet’s carbon dioxide-dominated atmosphere must once have been much thicker to limit surface evaporation. MAVEN has been orbiting Mars since 2014 on a quest to find out where all that CO went. It could have gone into the ice caps, into the rocks as carbonate minerals or it could have been lost to space. “People have spent decades looking for the carbonate minerals that would be the repository of CO and they haven’t found them,” says MAVEN team leader Bruce Jakosky at the Laboratory for Atmospheric and Space Physics in Boulder, Colorado. “That’s what has pushed the community into considering the role of escape to space.” The orbiter tracked two isotopes of argon in the atmosphere, argon-36 and argon-38. Because argon is unreactive, the only way it can leave Mars is when an ion smacks into one of its atoms and boots it off into space like a billiard ball, a process called sputtering. The heavier isotopes are harder to remove this way so, over time, Mars has ended up with more argon-38 than argon-36 in its atmosphere. Measuring the ratio of these two isotopes can tell us exactly how much argon the planet has lost. Assuming that the initial ratio was the same as on Earth and elsewhere in the solar system today – and accounting for other sources of argon like volcanic eruptions or incoming meteorites that would have returned some to the atmosphere – the MAVEN team worked out that about 66 per cent of the argon-36 that was ever in the Martin atmosphere has been sputtered away. From that, they calculated that 10 to 20 per cent of CO – equivalent to at least half a bar of atmospheric pressure – vanished through sputtering. And this is only a lower limit as other processes can remove carbon dioxide but leave argon unaffected, Jakosky says. Also considering these, he estimates that 80 to 90 per cent of the CO atmosphere was lost. It would have happened relatively quickly, too. Around 4.1 billion years ago, Mars’s magnetic field switched off for reasons we don’t understand. Without this field helping to hold it in place, the atmosphere became more vulnerable to sputtering from incoming charged particles from the solar wind. It may have taken just a few hundred million years for most of the atmosphere to be stripped away, the researchers say. “I think this is the explanation of why Mars went from a planet that is habitable by microbes at the surface, with warm temperatures and liquid water, to the cold, dry planet we see today,” Jakosky says.


News Article | April 17, 2017
Site: www.eurekalert.org

Mars has electrically charged metal atoms (ions) high in its atmosphere, according to new results from NASA's MAVEN spacecraft. The metal ions can reveal previously invisible activity in the mysterious electrically charged upper atmosphere (ionosphere) of Mars. "MAVEN has made the first direct detection of the permanent presence of metal ions in the ionosphere of a planet other than Earth," said Joseph Grebowsky of NASA's Goddard Space Flight Center in Greenbelt, Maryland. "Because metallic ions have long lifetimes and are transported far from their region of origin by neutral winds and electric fields, they can be used to infer motion in the ionosphere, similar to the way we use a lofted leaf to reveal which way the wind is blowing." Grebowsky is lead author of a paper on this research appearing April 10 in Geophysical Research Letters. MAVEN (Mars Atmosphere and Volatile Evolution Mission) is exploring the Martian upper atmosphere to understand how the planet lost most of its air, transforming from a world that could have supported life billions of years ago into a cold desert planet today. Understanding ionospheric activity is shedding light on how the Martian atmosphere is being lost to space, according to the team. The metal comes from a constant rain of tiny meteoroids onto the Red Planet. When a high-speed meteoroid hits the Martian atmosphere, it vaporizes. Metal atoms in the vapor trail get some of their electrons torn away by other charged atoms and molecules in the ionosphere, transforming the metal atoms into electrically charged ions. MAVEN has detected iron, magnesium, and sodium ions in the upper atmosphere of Mars over the last two years using its Neutral Gas and Ion Mass Spectrometer instrument, giving the team confidence that the metal ions are a permanent feature. "We detected metal ions associated with the close passage of Comet Siding Spring in 2014, but that was a unique event and it didn't tell us about the long-term presence of the ions," said Grebowsky. The interplanetary dust that causes the meteor showers is common throughout our solar system, so it's likely that all solar system planets and moons with substantial atmospheres have metal ions, according to the team. Sounding rockets, radar and satellite measurements have detected metal ion layers high in the atmosphere above Earth. There's also been indirect evidence for metal ions above other planets in our solar system. When spacecraft are exploring these worlds from orbit, sometimes their radio signals pass through the planet's atmosphere on the way to Earth, and sometimes portions of the signal have been blocked. This has been interpreted as interference from electrons in the ionosphere, some of which are thought to be associated with metal ions. However, long-term direct detection of the metal ions by MAVEN is the first conclusive evidence that these ions exist on another planet and that they are a permanent feature there. The team found that the metal ions behaved differently on Mars than on Earth. Earth is surrounded by a global magnetic field generated in its interior, and this magnetic field together with ionospheric winds forces the metal ions into layers. However, Mars has only local magnetic fields fossilized in certain regions of its crust, and the team only saw the layers near these areas. "Elsewhere, the metal ion distributions are totally unlike those observed at Earth," said Grebowsky. The research has other applications as well. For example it is unclear if the metal ions can affect the formation or behavior of high-altitude clouds. Also, detailed understanding of the meteoritic ions in the totally different Earth and Mars environments will be useful for better predicting consequences of interplanetary dust impacts in other yet-unexplored solar system atmospheres. "Observing metal ions on another planet gives us something to compare and contrast with Earth to understand the ionosphere and atmospheric chemistry better," said Grebowsky. The research was funded by the MAVEN mission. MAVEN's principal investigator is based at the University of Colorado's Laboratory for Atmospheric and Space Physics, Boulder. The university provided two science instruments and leads science operations, as well as education and public outreach, for the mission. NASA Goddard manages the MAVEN project and provided two science instruments for the mission. The University of California at Berkeley's Space Sciences Laboratory also provided four science instruments for the mission. Lockheed Martin built the spacecraft and is responsible for mission operations. NASA's Jet Propulsion Laboratory in Pasadena, California, provides navigation and Deep Space Network support, as well as the Electra telecommunications relay hardware and operations.


News Article | May 18, 2017
Site: motherboard.vice.com

Humans have accidentally created a protective bubble around Earth by using very low frequency (VLF) radio transmissions to contact submarines in the ocean. It sounds nuts, but according to recent research published in Space Science Reviews, underwater communication through VLF channels has an outer space dimension. This video explainer, released by NASA on Wednesday, visualizes how radio waves wafting into space interact with the particles surrounding Earth, and influence their motion. Satellites in certain high-altitude orbits, such as NASA's particle-watching Van Allen Probes, have observed these VLF ripples creating an "impenetrable boundary," a phrase coined by study co-author Dan Baker, director of the University of Colorado's Laboratory for Atmospheric and Space Physics. This doesn't mean impenetrable to spacecraft or asteroids, per se, but rather to potentially harmful particle showers created by turbulent space weather. Read More: How Space Weather Can Influence Elections on Earth The boundary extends out to the inner edge of the Van Allen radiation belts, which are bands of charged particles created from the clash of the solar wind against Earth's magnetic field. The VLF bubble might actually be pushing the Van Allen belts farther into space, suggests Baker, considering that they have receded farther from Earth since the 1960s, when VLF use was not as widespread. This byproduct of submarine dispatches is one of a few ways in which humans are known to have influenced space weather (nuclear weapons testing is another). Next, scientists are figuring out whether the VLF bubble can be used to purify the near-Earth environment from charged particles, which would make humanity a little safer. Well done, random radio-induced space cocoon. Subscribe to Science Solved It, Motherboard's new show about the greatest mysteries that were solved by science.


News Article | May 17, 2017
Site: www.eurekalert.org

Humans have long been shaping Earth's landscape, but now scientists know we can shape our near-space environment as well. A certain type of communications -- very low frequency, or VLF, radio communications -- have been found to interact with particles in space, affecting how and where they move. At times, these interactions can create a barrier around Earth against natural high energy particle radiation in space. These results, part of a comprehensive paper on human-induced space weather, were recently published in Space Science Reviews. "A number of experiments and observations have figured out that, under the right conditions, radio communications signals in the VLF frequency range can in fact affect the properties of the high-energy radiation environment around the Earth," said Phil Erickson, assistant director at the MIT Haystack Observatory, Westford, Massachusetts. VLF signals are transmitted from ground stations at huge powers to communicate with submarines deep in the ocean. While these waves are intended for communications below the surface, they also extend out beyond our atmosphere, shrouding Earth in a VLF bubble. This bubble is even seen by spacecraft high above Earth's surface, such as NASA's Van Allen Probes, which study electrons and ions in the near-Earth environment. The probes have noticed an interesting coincidence -- the outward extent of the VLF bubble corresponds almost exactly to the inner edge of the Van Allen radiation belts, a layer of charged particles held in place by Earth's magnetic fields. Dan Baker, director of the University of Colorado's Laboratory for Atmospheric and Space Physics in Boulder, coined this lower limit the "impenetrable barrier" and speculates that if there were no human VLF transmissions, the boundary would likely stretch closer to Earth. Indeed, comparisons of the modern extent of the radiation belts from Van Allen Probe data show the inner boundary to be much farther away than its recorded position in satellite data from the 1960s, when VLF transmissions were more limited. With further study, VLF transmissions may serve as a way to remove excess radiation from the near-Earth environment. Plans are already underway to test VLF transmissions in the upper atmosphere to see if they could remove excess charged particles -- which can appear during periods of intense space weather, such as when the sun erupts with giant clouds of particles and energy.


News Article | May 17, 2017
Site: www.sciencedaily.com

Humans have long been shaping Earth's landscape, but now scientists know we can shape our near-space environment as well. A certain type of communications -- very low frequency, or VLF, radio communications -- have been found to interact with particles in space, affecting how and where they move. At times, these interactions can create a barrier around Earth against natural high energy particle radiation in space. These results, part of a comprehensive paper on human-induced space weather, were recently published in Space Science Reviews. "A number of experiments and observations have figured out that, under the right conditions, radio communications signals in the VLF frequency range can in fact affect the properties of the high-energy radiation environment around the Earth," said Phil Erickson, assistant director at the MIT Haystack Observatory, Westford, Massachusetts. VLF signals are transmitted from ground stations at huge powers to communicate with submarines deep in the ocean. While these waves are intended for communications below the surface, they also extend out beyond our atmosphere, shrouding Earth in a VLF bubble. This bubble is even seen by spacecraft high above Earth's surface, such as NASA's Van Allen Probes, which study electrons and ions in the near-Earth environment. The probes have noticed an interesting coincidence -- the outward extent of the VLF bubble corresponds almost exactly to the inner edge of the Van Allen radiation belts, a layer of charged particles held in place by Earth's magnetic fields. Dan Baker, director of the University of Colorado's Laboratory for Atmospheric and Space Physics in Boulder, coined this lower limit the "impenetrable barrier" and speculates that if there were no human VLF transmissions, the boundary would likely stretch closer to Earth. Indeed, comparisons of the modern extent of the radiation belts from Van Allen Probe data show the inner boundary to be much farther away than its recorded position in satellite data from the 1960s, when VLF transmissions were more limited. With further study, VLF transmissions may serve as a way to remove excess radiation from the near-Earth environment. Plans are already underway to test VLF transmissions in the upper atmosphere to see if they could remove excess charged particles -- which can appear during periods of intense space weather, such as when the sun erupts with giant clouds of particles and energy.


News Article | May 23, 2017
Site: www.businesswire.com

LUXEMBOURG--(BUSINESS WIRE)--SES (Euronext Paris:SESG) (LuxX:SESG) today announced the successful integration of NASA’s Global-Scale Observations of the Limb and Disk (GOLD) hosted payload with SES-14. GOLD will employ an ultraviolet imaging spectrograph to measure densities and temperatures in the Earth’s thermosphere and ionosphere in response to Sun-Earth interaction. It is aimed at revolutionizing scientists’ understanding of this part of the space environment and its impacts on low Earth orbit satellite drag (a force acting opposite to the direction of motion, slowing the satellite), and ionospheric disruptions of communication and navigation transmissions. GOLD will take unprecedented images of the temperature and composition changes over a hemisphere. GOLD is a result of collaboration among several world-leading entities. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, is providing overall NASA program management, while the University of Central Florida’s Florida Space Institute is the Principal Investigator for the project. The GOLD instrument was built and will be operated by the University of Colorado Boulder Laboratory for Atmospheric and Space Physics. Satellite operator SES and its fully-owned subsidiary SES Government Solutions are providing the host satellite, mission operations, and science data transport. The project was developed in close partnership with Airbus Defence and Space, the company which is building the SES-14 spacecraft for SES. SES Government Solutions is exclusively focused on meeting the satellite communications needs of the U.S. Government and its agencies. Leveraging more than four decades of experience in the government SATCOM market, SES Government Solutions offers robust and secure end-to-end satellite communications solutions. “Using a host satellite makes access to space quicker and more cost efficient, while meeting the increasingly more sophisticated needs governments have nowadays. SES has extensive experience in hosted payload projects and is well-suited to meet these needs,” said Pete Hoene, President and CEO of SES Government Solutions. “We are very excited about hosting GOLD, and looking forward to it starting its important mission in space.” Testing and preparation of SES-14 and GOLD are on-going in Toulouse, France, in anticipation of a late 2017 launch on a SpaceX Falcon 9 from Kennedy Space Center in Cape Canaveral, Florida. The SES-14 satellite will provide coverage of the Americas, Atlantic Ocean, Western Europe, and Northwest Africa with High Throughput Satellite (HTS) services and Ku-band & C-band wide beam services. The wide beams will serve growing video neighborhoods in the Americas and also support existing VSAT services. The HTS Ku-band multi-spot beams will serve traffic-intensive data applications such as mobile backhaul, maritime and aeronautical services. SES white papers are available under https://www.ses.com/news/whitepapers SES is the world-leading satellite operator and the first to deliver a differentiated and scalable GEO-MEO offering worldwide, with more than 50 satellites in Geostationary Earth Orbit (GEO) and 12 in Medium Earth Orbit (MEO). SES focuses on value-added, end-to-end solutions in two key business units: SES Video and SES Networks. The company provides satellite communications services to broadcasters, content and internet service providers, mobile and fixed network operators, governments and institutions. SES’s portfolio includes the ASTRA satellite system, which has the largest Direct-to-Home (DTH) television reach in Europe, O3b Networks, a global managed data communications service provider, and MX1, a leading media service provider that offers a full suite of innovative digital video and media services. Further information available at: www.ses.com


News Article | February 15, 2017
Site: www.newscientist.com

Danger zones in the air where radiation levels surge could pose an unrecognised health hazard. Airliners may have to avoid these in future, just as they do with volcanic ash clouds, to minimise any risk to travellers and crew. We have long known that high-altitude flight exposes us to cosmic rays. The radiation dose on a flight from London to Tokyo is roughly equivalent to a chest X-ray. Now research flights have revealed the existence of “clouds” where radiation levels can be at least double the usual level. They were discovered as a result of the NASA-funded Automated Radiation Measurements for Aerospace Safety (ARMAS) programme, which aims to develop new methods of measuring and monitoring high-altitude radiation. In 265 flights, radiation levels detected generally followed the expected pattern, but in at least six instances they surged, as though the aircraft was flying through a radiation cloud. “We have seen several cases where the exposure is doubled while flying through the cloud,” says ARMAS principal investigator W. Kent Tobiska, of Los Angeles firm Space Environment Technologies. “It is quite variable and can easily be more or less than that.” Even higher levels have been recorded in some cases, but those results remain unpublished while the team considers alternative explanations for the data. Tobiska says the two main sources of radiation, cosmic rays and the solar wind, can’t account for the surges. “Our new measurements show a third component.” The surges coincided with geomagnetic storms. This points the finger at energetic electrons being lost from the outer Van Allen radiation belts, where charged particles mostly from the solar wind are trapped by Earth’s magnetic field. Tobiska believes that such a storm can liberate electrons trapped in the Van Allen belts. “Those electrons are driven into the upper atmosphere, collide with nitrogen and oxygen atoms and molecules, and then create a spray of secondary and tertiary radiation, likely in the form of gamma rays.” This radiation, he thinks, is what the ARMAS flights are detecting across a wide area. Daniel Baker of the University of Colorado’s Laboratory for Atmospheric and Space Physics says this mechanism seems feasible. “It is plausible that the ARMAS results are related to enhanced loss of radiation belt particles from the magnetosphere into the middle and lower atmosphere.” There are no set standards for radiation safety in US aviation at present, but Tobiska says that regulations are likely in the next few years. The absolute risk may be low, as a chest X-ray only increases the risk of a fatal cancer by 1 in 200,000, but these must be balanced against the large number of flights and whether risk is avoidable. “This is mainly for crew members,” says Tobiska, “but would certainly benefit frequent flyers and even fetuses in their first trimester.” ARMAS work using satellite data and airborne sensors may allow the radiation “clouds” to be tracked. Tobiska says that in future, flights may be diverted or directed to a lower altitude to avoid them.


News Article | February 10, 2017
Site: www.techtimes.com

A new study on the absence of liquid water on the surface of Mars has suggested that an easy escape route of hydrogen from the high altitude upper atmosphere is one of the major reasons. In the study, researchers at the University of Colorado debunked the earlier assumption of slower loss of water from Mars and argued that the planet lost liquid water at a rapid pace. The new theory refutes earlier models that said Martian hydrogen escaped slowly yet steadily. "Going back to the 1970s, the conventional picture of Martian hydrogen loss has been one of slow, steady escape over long time scales," said Mike Chaffin, lead author of the new study and a research associate at Laboratory for Atmospheric and Space Physics. According to data from Mars Express, one reason for the rapid hydrogen escape was the floating of water molecules at unusually higher altitudes when the Red planet warms up during summers. This is in contrast to "cold trap" mechanism existing on Earth for keeping atmospheric water closer to the ground. When the water molecules pile up in the middle atmosphere, ultraviolet rays break them into oxygen and hydrogen. After this, an easy escape by hydrogen follows by defying the Mars' low gravity. The study has been published in Nature GeoScience. Though consolidating the findings will require more validations from other data, the finding is significant in underscoring that Mars lost water at a differential rate and no uniform time scale existed. Chaffin noted that there was high seasonal variation in the matter of water loss from Mars than thought earlier. Drastic variations in the hydrogen escape were documented by Hubble Telescope of NASA and the Mars Express of ESA way back in 2007. The data said the rate of hydrogen escape became 100 times more than the normal rate when the orbit of Mars came closest to the sun. That makes the old model of slow hydrogen escape from Mars pretty inadequate. Previous models made a case of water molecules in the Martian atmosphere getting "cold trapped" at lower levels as vapor abundance was low at high altitudes. This was the mechanism with regard to water molecules in Earth's atmosphere. However, that process does not work with Mars as shown by Mars Express data. What actually happens is, when the lower atmosphere of Red Planet heats up during southern summer, water molecules keep rising higher than normal in the atmosphere and bypass the cold trap to move into middle altitudes. Ultraviolet light rays split the water molecules to produce atomic oxygen and hydrogen. When hydrogen moves up the higher altitudes thanks to its low weight, the gas escapes the Martian gravity while leaving the heavier oxygen behind. More details on the hydrogen escape may be gauged by the observations Mars Atmosphere and Volatile Evolution spacecraft that is studying the Martian upper atmosphere and Trace Gas Orbiter of ESA that starts Martian studies in 2018. The co-authors of the study included LASP planetary scientists Justin Deighan, Nick Schneider, and Ian Stewart. © 2017 Tech Times, All rights reserved. Do not reproduce without permission.


News Article | February 15, 2017
Site: www.newscientist.com

MARS has a real water shortage. It seems we have either misunderstood what its early years were like – or vast amounts of water are hiding beneath its surface. A lot of evidence points towards Mars being warm and wet early in its history; features that look like rivers, lakes and outflows have been spotted both from orbit and by rovers on the surface, and a lot of the planet’s minerals contain water. So where did all this water go? The Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft was sent to find the answer. Since its arrival at Mars in 2014, it has been measuring how much atmosphere Mars is losing to space. From that, we can figure out how much it had in the past. The orbiter keeps track of both the activity of the sun and the ions streaming away from the planet’s atmosphere to build up an inventory of everything that enters and leaves over time. It also estimates the total loss by measuring the fraction of heavier isotopes of certain atoms versus their lighter counterparts. As the lighter versions are easier to knock out into space with a stray cosmic ray or extra energy from solar photons, a higher fraction of heavy isotopes remaining in Mars’s present-day atmosphere means much of the original atmosphere has been lost. MAVEN focuses on hydrogen and oxygen as ways to trace water and carbon dioxide, and neutral argon as a way to measure the sheer volume of atmosphere loss. Based on measurements of these taken over a full Martian year, the team concludes that about 4 billion years ago, the Red Planet’s atmospheric pressure – currently less than 1 per cent of Earth’s – was up to 1.5 times what Earth’s is today. They also found that it could have had the equivalent of a global ocean between 2 and 40 metres deep in its distant past. “It’s a consistent story,” said team leader Bruce Jakosky at the Laboratory for Atmospheric and Space Physics in Boulder, Colorado, who presented the findings at the American Geophysical Union meeting in San Francisco in December. “Loss of gas to space is likely a major if not the major process for changing the Mars climate through time.” The trouble is, that’s less water than expected. In 2015, James Head at Brown University and Michael Carr at the US Geological Survey estimated that the equivalent of a global ocean a few hundred metres deep was needed to explain all the geological features that look like they were formed by water. “We were counting on their loss rate to explain it,” Head says. “And they didn’t come through.” One possible reason for the discrepancy is that the long-held notion of Mars being like Earth in the past is wrong. One theory has it that the planet was actually cold and dry, and that streams and rivers formed underneath the ice pack instead of via water flowing on the surface. All that would be needed is a slightly denser CO atmosphere – which MAVEN’s measurements suggest you had. “Loss of gas to space is likely a major process for changing the Mars climate through time” The other option is that the water is hidden away somewhere, maybe underground. Dark streaks recently spotted on crater rims that look like they could be liquid water may be fed by underground aquifers, for instance. “Either it’s hidden somewhere, or there wasn’t that much to start with,” says Carr. This article appeared in print under the headline “Where did all the Martian water go?”


Kopp G.,Laboratory for Atmospheric and Space Physics | Lean J.L.,U.S. Navy
Geophysical Research Letters | Year: 2011

The most accurate value of total solar irradiance during the 2008 solar minimum period is 1360.8± 0.5 W m-2 according to measurements from the Total Irradiance Monitor (TIM) on NASA's Solar Radiation and Climate Experiment (SORCE) and a series of new radiometric laboratory tests. This value is significantly lower than the canonical value of 1365.4± 1.3 W m -2 established in the 1990s, which energy balance calculations and climate models currently use. Scattered light is a primary cause of the higher irradiance values measured by the earlier generation of solar radiometers in which the precision aperture defining the measured solar beam is located behind a larger, view-limiting aperture. In the TIM, the opposite order of these apertures precludes this spurious signal by limiting the light entering the instrument. We assess the accuracy and stability of irradiance measurements made since 1978 and the implications of instrument uncertainties and instabilities for climate research in comparison with the new TIM data. TIM's lower solar irradiance value is not a change in the Sun's output, whose variations it detects with stability comparable or superior to prior measurements; instead, its significance is in advancing the capability of monitoring solar irradiance variations on climate-relevant time scales and in improving estimates of Earth energy balance, which the Sun initiates. Copyright 2011 by the American Geophysical Union.

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