The 8th annual Institution of Geospatial and Remote Sensing Malaysia (IGRSM) International Conference and Exhibition on Geospatial & Remote Sensing will be held April 13–14 in Kuala Lumpur, Malaysia, supporting organizer Science & Technology Research Institute for Defence (STRIDE) announced in a news release. The conference, themed “Geospatial on the Go,” is aimed at disseminating knowledge and sharing expertise in geospatial sciences in all aspects of applications. It also aims to build linkages between local and international professionals in this field with industries, STRIDE said.
Highlights of the conference include keynote presentations: “Next-Generation Remote Sensing With Micro-Satellite” by Yukihiro Takahashi, Ph.D., director of Hokkaido University’s Space Mission Centre in Japan; and “The Rise of Small UAVs Applications: Opportunities and Challenges” by Reza Ehsani, Ph.D., associate professor at the University of Florida’s Citrus Research and Education Center in the U.S.
Other presentations will cover technology trends, infrastructure and urban planning, land use, land cover mapping, disaster management and environmental monitoring.
Awards for best paper and best student paper will be presented during the conference’s closing ceremony.
The ENVI Analytics Symposium (EAS), scheduled for Aug. 25-26 in Boulder, Colo., will bring together experts in remote sensing science to discuss technology trends and the next generation of solutions for advanced analytics.
Geospatial analytics are important because they can be applied to a diverse range of needs in environmental and natural resource monitoring, global food production, security, urbanization, and other fields of research, according to event organizer, Exelis.
The need to identify technology trends and advanced analytic solutions is being driven by the staggering growth in high-spatial and spectral resolution earth imagery, radar, LiDAR, and full-motion video data. Join your fellow thought leaders and practitioners from industry, academia, government, and non-profit organizations in Boulder, Colo., for an intensive exploration of the latest advancements of analytics in remote sensing.
Sponsors and attendees represent organizations such as Airbus Defence and Space, U.S. Fish & Wildlife Services, DigitalGlobe, U.S. Geological Survey, Esri, Naval Post Graduate School, Oak Ridge National Lab and more.
A new concept that involves mounting an instrument on the International Space Station and taking advantage of signals from navigation satellites could provide measurements of sea-surface height and information about features related to ocean currents, benefiting science and ocean forecasting.
We have all seen the beautiful photographs of our planet taken by astronauts, but orbiting Earth 16 times a day just 400 km above, the Space Station also offers a platform from which to measure certain variables related to climate change.
So, in 2011 the European Space Agency (ESA) called for proposals to explore how the Space Station could be used to make scientifically valid observations of Earth. After reviewing and assessing numerous proposals, the result is to further develop the GEROS-ISS mission concept.
Jason Hatton, GEROS-ISS project coordinator, said, “The concept is still going through feasibility studies, but the aim is to launch the experiment towards the end of 2019. It would be carried to the Space Station on a cargo vehicle and installed on ESA’s Columbus space laboratory using a robotic arm, after which GEROS-ISS would run for at least a year.”
GEROS-ISS stands for GNSS reflectometry, radio occultation and scatterometry on board the ISS. GPS and Galileo satellites send a continual stream of microwave signals to Earth for navigation purposes, but these signals also bounce off the surface and back into space.
The idea is to install an instrument with an antenna on the Space Station that would capture signals directly from these satellites as well as signals that are reflected or scattered from Earth. This process could be used to calculate the height of the sea surface, and to measure waves — or “roughness” — that can then be used to work out the speed of surface winds.
Variations in sea-surface height (cm) obtained by merging multiple altimeter measurements. GEROS-ISS would be able to observe this variability so that maps covering latitudes 51° N to 51° S can be produced every four days. (Photo: ESA)
GEROS-ISS is primarily an experiment to demonstrate new ways of observing Earth. However, if taken beyond the testing phase this new approach would complement measurements from satellites carrying altimeters such as CryoSat and Sentinel-3, and satellites carrying wind scatterometers such as MetOp.
Importantly, it is the first concept to assess the potential of spaceborne GNSS reflectometry to determine and map ocean height at scales of 10–100 km or longer in less than four days. Current satellite altimeters, in comparison, offer global maps at scales of around 80 km, which are produced from multiple datasets every 10 days.
A system based on GEROS-ISS would, therefore, complement existing satellite systems, helping to map ocean variability at finer spatial and temporal scales over a range of seas in tropical and temperate regions. It would also refine our understanding of how well the concept would work for measuring the roughness of the ocean surface.
In this respect, the development of GEROS-ISS benefits from experience gained with the UK’s TechDemoSat-1, which also measures ocean-surface roughness using a similar technique. It is also hoped that NASA’s upcoming CYGNSS constellation of mini satellites will help pave the way for GEROS-ISS.
In addition, GEROS-ISS uses a technique called radio occultation whereby the antenna receives signals that are refracted as they pass through the atmosphere. This can be used to generate vertical profiles of atmospheric humidity, pressure and temperature, as does the GRAS instrument on the MetOp satellites, for example.
GEROS-ISS will be installed on the upper balcony of ESA’s Columbus space laboratory, which provides mechanical interface plates as well as power, command and data links to the ISS systems. (Photo: ESA, taken by ESA astronaut Luca Parmitano during his spacewalk on July 9, 2013. )
“It is very flexible, combining different mission concepts and applications in one: GNSS-reflectometry to determine sea-surface height, scatterometry to measure sea-surface roughness and radio occultation for atmospheric studies,” said Jens Wickert who leads the science team that proposed GEROS-ISS.
ESA engineer Manuel Martin-Neira noted, “The original concept actually goes back over 20 years and has matured considerably through numerous studies and campaigns, however, it has never been duly tested from space.”
“Being able to use the International Space Station in this way means that we can quickly validate innovative observing techniques without having to build an entire satellite, and we expect this to lead to new opportunities for science,” added Michael Kern, ESA’s GEROS-ISS mission scientist.
The GEROS-ISS feasibility studies are being carried out through ESA’s General Studies Programme.
Editor’s Note:GPS World discussed the use of GPS for radio occultation in itsMarch 1994 Innovation column, “Monitoring the Earth’s Atmosphere with GPS,” by Rob Kursinski.
SBG Systems has released the Apogee Series, its most accurate inertial navigation systems based on robust and cost-effective MEMS technology. The INS/GNSS integrates the latest generation of MEMS sensors and a tri-frequency GNSS receiver. Apogee achieves 0.008° in roll and pitch in real-time and 0.005° in post-processing. With two antennas, it delivers a robust and accurate heading.
Four models compose the Apogee line.
The Apogee-A provides only orientation data.
The Apogee-N additionally embeds a GNSS receiver; it is a compact solution with one antenna for land and aerial applications.
The Apogee-D embeds a dual-antenna GNSS receiver for accurate heading under low dynamics conditions.
The Apogee-E delivers navigation data when connected to an external GNSS receiver or to the SplitBox with integrated GNSS.
Mobile Mapping. Apogee can be precisely synchronized with LiDAR equipment because of a UTC time-stamping accurate to 1 microsecond. This integrated INS/GNSS provides optimal position in multipath environment or during GNSS outages, thanks to a tight GNSS integration and the continuous fusion of inertial and odometer data. To get the required positioning accuracy, Apogee supports RTK and Precise Point Positioning services (Omnistar, Terrastar, and more).
Aerial Mapping and Remote Sensing. With very low noise gyroscopes, low latency, and high resistance to vibrations, the Apogee allows aerial surveys by plane or helicopter. It provides real-time orientation and position data with direct fusion of inertial and GNSS information. Compact, lightweight and low power, the Apogee is easy to install, and has an embedded web interface for configuration.
Post-processing. Orientation and position data can be recorded in the Apogee data logger. At the office, the user imports data in the post-processing software. This tool gives access to several RTK networks and reference station offline data (such as VRS and CORS.) Additionally, it enhances orientation and position accuracy by a complete “backward/forward” calculation.
“SBG Systems manufactures inertial systems from the concept to the production. The Apogee benefits from our high level of expertise in integrated design, IMU calibration, testing, and filtering,” said Alexis Guinamard, CTO of SBG Systems.
All models are available for order. Below is a promotional video with more information.
Editor’s Note: Tony Murfin is managing consultant for GNSS Aerospace LLC and editor of GPS World’s monthly Professional OEM newsletter. The views expressed are his own.
Another year has gone by, with another year of further improvements in navigation performance of micro-electro-mechnical systems (MEMS) inertial products. SBG Systems in France is now fielding a new generation of MEMS inertial products for much higher accuracy applications.
SBG Systems is based in Rueil-Malmaison, less than eight miles west of the center of Paris. Founded in 2007, SBG has developed a number of innovative MEMS inertial products over the last seven years, along with a respected reputation in the navigation industry, and by 2014 the company was recognized as the 26th fastest growing company in France.
The roots of the company began to form at the end of 2004, when a group of ECE School of Engineering students in Paris put a team together for a new UAV competition. The goal was to build a UAV of less than 1 kg, capable of flying autonomously indoors — at the time, a significant technical challenge. In 2004, miniature INS was not commercially available, so the team decided to build one, as well as other electronic parts such as the autopilot. The competition ran out of money, but the design was a success and led to a working UAV. The INS was by far the most advanced part of the project.
The students went back to their studies and took internships at UAV companies and ONERA (French aeronautics, space and defense research labs), but they still believed in the need for low-cost navigation solutions for the emerging civilian UAV market.
So, in 2007, three of the students — Raphaël Siryani, Thibault Bonnevie and Alexis Guinamard, S, B and G — formed SBG Systems with the goal of providing affordable, highly accurate MEMS inertial navigation systems for UAVs.
SBG quickly received its first Innovation Award from the French Research Ministry, and with this funding launched the IG-500 series of MEMS AHRS and INS in December 2008.
The company has since grown into a worldwide player with a strong product innovation focus. UAVs are still an important part of revenue, but the company has diversified into:
Aerospace and defense applications (UAVs, gimbaled cameras, antenna tracking, etc.)
Marine and offshore activities (ROV/AUVs, buoys, etc.)
Survey (hydrography, mobile mapping, aerial LiDAR, etc.)
SBG Systems has a small staff of mostly development and sales engineers — graduate students and experts. SBG has recruited navigation experts and some sales people from key players in the inertial business. Most (95%) have at least a master’s degree in engineering — R&D has 45% of the staff, and 40% are in sales, marketing and technical support. Production has been extremely automated and requires very few staff for in-house system assembly, calibration and final acceptance test. They do expect to double in size over the next two to three years.
The company is owned by the three founders, who still lead operations. SBG grew 1,304% over the last five years, and last year was ranked the 26th fastest growing company in France on the Deloitte Fast50. Today, SBG Systems has fielded more than 4,000 attitude and heading reference systems (AHRS) and INS (mostly INS), with almost a third of those delivered last year. The company forecasts growth for the next five years to be at this same phenomenal rate! SBG Systems currently offers a line of MEMS inertial sensors that include AHRS, inertial measurement units (IMU), and INS with embedded GPS (INS/GPS).
Ellipse-D dual-antenna mini INS/GNSS.
Not only have MEMS sensors improved in performance, but SBG has also developed advanced calibration capabilities that allow it to reach high-precision performance approaching high-end ring laser gyro accuracies in much smaller, less expensive packages. SBG owns an extensive set of temperature chambers combined with rotary tables and vibrating tables. Each SBG system gets to stay two to five days inside these calibration tools. But the “secret sauce” is in a state-of-the-art SBG developed calibration algorithm…
SBG buys MEMS gyros and accelerometers from MEMS manufacturers such as Colibrys, Analogue Devices and Silicon Sensing and builds complete inertial systems. The team embeds different GNSS receivers, depending on the product line and intended application — from miniature automotive-grade chipsets from u-blox to the very best from the key survey-grade players such as Septentrio, NovAtel and Trimble. Some customers may already have their own GNSS receiver, so SBG has developed and tuned their systems to work with any of these big manufacturers. The antenna employed depends on the receiver being used — from Tallysman Wireless and Antcom to Trimble, Septentrio or NovAtel — a very diversified range of antennas.
Ellipse-E.
SBG announced the Ellipse-D dual-antenna mini INS/GNSS earlier this month. The Ellipse-D is a miniature INS with an embedded dual-antenna survey-grade GNSS receiver for high-accuracy orientation and positioning.
Independent hydrographic testing in October 2014 of earlier model designs has already shown accuracy improvements, and the latest D version promises even better performance. The products tested were:
Ekinox-D
Ellipse-E, miniature inertial navigation system connected to a Hemisphere VS330 GNSS with two antennas.
Ekinox-D, inertial navigation system integrating a dual-frequency GNSS receiver with two antennas.
The test was a typical marine survey, with each leg about 550 meters long. Attitude performance was compared to a fiber-optic gyro compass reference system with much higher roll and pitch accuracy than the two SBG products under test.
Ellipse-E roll and pitch accuracy is better than the specs. The use of an RTK GNSS receiver additionally improves the sensor’s performance. The Ekinox-D also has good results — around 0.03° in both roll and pitch. SBG claims that low-noise gyroscopes and advanced algorithms are the basis for this performance.
The SBG list of 250 customers in 30 countries includes some impressive names, many outside Europe, and the company claims to have nearly 4,000 inertial sensors in the field. So this is not a prototype shop, but more a fully equipped production facility. SBG has opened an office in Chicago to address the North American market.
So, what are people doing with these devices? There are a number of applications in aerospace, land, marine and sub-sea.
In the aerospace industry, SBG sensors are used for UAV navigation and flight analysis — they could eventually be incorporated in certified avionics. They are also used for antenna tracking, camera stabilization and more demanding applications such as LiDAR orientation and data georeferencing.
An Ekinox-N INS with embedded GNSS receiver was installed for the tests in a single-engine general aviation aircraft flying out of Magdeburg, Germany. A typical airborne survey-type flight was flown under mixed weather conditions with some turbulence, and roll, pitch, and altitude data was collected for real-time analysis and was also post-processed. A high-grade FOG-based AHRS was used as reference unit — with very high accuracy gyroscopes.
The flight pattern was typical of survey applications, with parallel straight lines of about 8.5 km. Altitude was 600 m and cruise speed was about 200 km/h.
Roll
Pitch
RMS Error Real Time (max)
0.043° (0.16)
0.043° (0.16)
RMS Error Post Processing (max)
0.017° (0.19)
0.025° (0.20)
Real-time accuracy remained below 0.05° RMS for roll and pitch. Post-processed output had a lower RMS error and a better stability over the whole flight. Only one GPS antenna was used in this test with Ekinox-N; nevertheless, heading reached an estimated accuracy of 0.06° when post-processed. The Ekinox-D model provides more accurate heading thanks to its integrated dual-antenna and GNSS receiver.
The Ekinox-N has been integrated on a UAV by Headwall in the U.S. for remote-sensing applications.
Headwall is a leading designer and manufacturer of high-performance hyperspectral imaging sensors for harsh environments. As a pioneer for remote-sensing applications, Headwall is the first to market a fully integrated remote-sensing solution combining hyperspectral and LiDAR sensors on a small UAV. This “total solution” approach has been welcomed by the remote-sensing market because it quickens time to deployment, decreases implementation costs, and enables operations in harsh environments.
The multi-rotor UAV carries Headwall’s lightweight Micro-Hyperspec VNIR hyperspectral sensor and a Velodyne LiDAR unit. The LiDAR collects a point cloud that reflects the field’s topographic relief, and the hyperspectral sensor delivers a picture showing spectral signatures of every object within the field of view. The SBG inertial navigation system has an embedded GPS and is used to provide positioning and orientation data. Weight is a key factor — Ekinox-N weighs only 500 grams, even though it integrates a survey-grade L1/L2 GNSS sensor to provide accurate positioning and precision roll, pitch, and heading data.
Mounted on the UAV, the Ekinox-N provides LiDAR and the hyperspectral camera with orientation and position during the whole flight. This and other data is recorded in real time at 200 Hz within the onboard computer. On the ground, the Headwall post-processing Hyperspec software fuses all sensor information. Ekinox-N data allows every scanned point and every pixel to be georeferenced and be tilt compensated to within a centimeter.
SLAM-based Indoor Mapping System by VIAmetris.
For miniature inertial sensors, smaller and lighter applications are possible at less cost. One of these applications includes the SLAM-based Indoor Mapping System by VIAmetris.
Simultaneous localization and mapping (SLAM) is becoming increasingly important to enable efficient indoor mapping. VIAmetris has created a different spin on indoor mapping with the “MID” portable SLAM-based scanner. This handheld system integrates a 2D LiDAR, a camera, an SBG Ellipse-A AHRS, and a tablet PC that shows the map being drawn while the user walks around inside the building. The AHRS also compensates for movement while orienting the generated maps to the north.
While the user walks, the 2D LiDAR scans in a horizontal plane by measuring 43,000 points per second across a 270° field of view. The SLAM technology progressively builds the map in the shape of lines made of points. At the office, the surveyor imports the data into the post-processing software and uses the lines of points to design the map. If there is any doubt about a specific shape — whether it is actually wall or furniture, for example — a photo of the location is available as MID automatically takes contextual pictures every meter, or whenever there is a change of direction, or manually.
The centimeter-level accurate map is then ready to be imported into most CAD software. As the system works without GPS, the generated map is not georeferenced or in a local coordinate reference system. To do so, the user links MID’s points cloud to a known point and all data is automatically referenced. MID is much easier to use than a laser distance meter, a tachometer, or a 3D scanner, and significantly reduces the time required for indoor mapping.
SBG is now working more often in the marine industry, equipping boat, cranes, or instrumented buoys. The company has even developed a specific solution for the hydrographic market. The SBG Ekinox Hydrography Solution integrates Ekinox-U which operates to a depth of 200 meters, and incorporates a SplitBox with a built-in tri-band RTK GNSS receiver and uses Terrastar, OmniSTAR, or Marinestar corrections.
The SBG Ekinox Hydrography Solution.
For subsea operations, positioning is required for ROVs and AUVs that navigate for minutes or sometimes for hours underwater. GPS fixes are only available when the vehicle comes close to the surface. But operators usually try to expend the time they are able to operate close to the seabed. To avoid typical INS drift, different aiding sources are used — the three main ones are acoustic positioning, Doppler velocity loggers (DVLs) and depth sensors.
Acoustic position is far more noisy and unstable than GPS.
DVL is a kind of 2D odometer, providing speed over the seabed.
The INS and the Kalman filter therefore play a key role to provide reference heading and reliable position data.
It’s a major concern when you have a massive ROV working on pipes under an offshore platform. Any mistake can cause severe damage and cost millions.
So SBG is moving along and taking on new, challenging applications with a range of MEMS inertial products that appear to be growing quite rapidly, with ever-improving performance. Once upon a time, we couldn’t stay anywhere within RTK-level performance during GPS outages because of the high drift-rate of MEMS inertial devices. Now, SBG has introduced its latest Ellipse-D dual-antenna mini INS/GNSS spec’ed at 0.1° real time for pitch and roll, with 2-cm RTK position.
The Apogee INS/GNSS.
And just today, SBG Systems has even bigger news with the release of the Apogee series, which is Apogee’s most accurate, robust and cost-effective MEMS technology inertial navigation system. The Apogee INS/GNSS integrates the very latest generation of MEMS sensors along with a triple-frequency GNSS receiver, achieving 0.008° in roll and pitch in real time, and 0.005° in post-processing. With two antennas, it also provides reliable and accurate heading.
Amazing what scientific skill, focused investment and time has done for MEMS inertial technology!
The company PlanetiQ plans to use GNSS to make real-time weather forecasts. PlanetiQ plans to launch a commercial weather satellite constellation by 2017, composed of 12 to 18 small satellites that will capture data as GNSS satellites pass through Earth’s orbital horizon.
The satellites will use radio occultation to collect data that will supplement computer models on weather, producing more accurate and timely weather forecasts and assessments, PlanetiQ said. The satellites will measure how GPS, GLONASS, and BeiDou radio waves bend as they travel through the atmosphere, a technique that provides snapshots of temperature, pressure and water vapor, as well as insight into whether solar storms are active in the ionosphere, reports Discovery News.
Figure credit: PlanetiQ.
More than 30,000 occultation measurements can be collected each day.
PlanetiQ is one of five companies in the United States looking to commercialize weather forecasting. GeoOptics is working on a similar system and plans to launch its first satellite this year.
Explore further:
PlanetiQ President and CEO Anne Hale Miglarese discussed the project on The Weather Channel in August 2014.
Attila Komjathy, a NASA Jet Propulsion Laboratory principal investigator and adjunct professor in the University of New Brunswick’s Department of Geodesy and Geomatics Engineering, was named a Fellow of the Institute of Navigation in January for his work on remote sensing of the Earth’s ionosphere using signals from GNSS.
NASA is soliciting research on remote sensing techniques that use GNSS for studying the Earth’s environment.
Specifically, the announcement says NASA “seeks innovative approaches to the development of Global Navigation Satellite System (GNSS) remote sensing techniques and algorithms to study the Earth’s environment from the ionosphere to Earth’s interior.” The announcement says NASA is seeking to emphasize the use of reflected GNSS signals for the characterization of the Earth’s surface and mitigation of natural hazards.
Notices of Intent are requested by January 20, 2015, and the due date for proposals is March 20, 2015.
NASA solicits research through the release of various research announcements in a wide range of science and technology disciplines. NASA uses a peer review process to evaluate and select research proposals submitted in response to these research announcements. NASA says that researchers can help achieve national research objectives by submitting research proposals and conducting awarded research. Visit the announcement page for details.
The GPS Reflections Group of University of Colorado-Boulder has been awarded the prestigious Prince Sultan Bin Abdulaziz International Creativity Prize for Water. The prize is awarded biannually to acknowledge innovative work that contributes to the sustainable availability of water and the alleviation of the global problem of water scarcity.
The awards will be presented in a ceremony in Riyadh, Saudi Arabia, on December 16, concurrently with the 6th International Conference on Water Resources and Arid Environments (ICWRAE 6), December 16-18, 2014.
Professors Kristine Larson and Eric Small developed a new method to measure water at the Earth’s surface. The research team discovered that standard geodetic GPS instruments are sensitive to hydrological influences. They subsequently developed a cost-effective technique, GPS Interferometric Reflectometry (GPS-IR), to measure soil moisture, snow depth, and vegetation water content around GPS antennas. GPS-IR has the advantage of relying on an existing GPS infrastructure installed by surveyors and geoscientists that covers an increasingly large portion of the global surface.
Larson and Small collaborated with scientists at the University Corporation for Atmospheric Research and the National Atmospheric and Oceanic Administration, also in Boulder.
The team uses the GPS-IR technique to analyze data streams from existing GPS networks in near real-time. Data from hundreds of operational GPS sites are downloaded and processed, yielding estimates of hydrologic variables within 24 hours.
Scientists and government agencies can access this information at the team’s web portal and use the data to improve monitoring and forecasting of hydrologic variables.
A hail suppression project dubbed RO-BERTA by the University of Applied Sciences, Rosenheim (Germany), has been selected the winner of the European Satellite Navigation Competition’s (ESNC) University Challenge. Judged by an international expert jury, the University Challenge is a special prize to reward innovative ideas emerging from Europe’s universities.
The Hail Navigator system is designed to reduce damage caused by hail. Based on the premise of suppressing the formation of hail by injecting silver iodide into clouds, Hail Navigator combines navigation with a precipitation reporting system that can guide pilots to optimal locations for hail suppression missions.
The system is complemented by weather observations (including precise times and locations) reported by local citizens via a smartphone app, which aids the validation of weather prediction models. These models constitute an important factor in deciding whether a hail suppression flight is necessary.
The project team was awarded the prize on October 23 in Berlin at the ESNC Awards Ceremony. More than 300 guests attended, representing the top European players in the navigation sector. In addition to cash, the prize includes support through the GNSS Research & Applications Centre of Excellence (GRACE) and a free ticket to the Munich Satellite Navigation Summit 2015.
“Winning this prize once again demonstrates that interdisciplinary cooperation is feasible and successful,” said Project Manager Peter Zentgraf. “The positive feedback the competition provides helps drive our many students to continue their dedicated work, which made it possible to reach our project goals.”
Rarely formed sheets of ice push rocks across a dry lake in Death Valley.
In Racetrack Playa in Death Valley, California, hundreds of rocks — some weighing as much as 700 pounds — seem to have been dragged across the ground, leaving synchronized trails that can stretch for hundreds of meters. Though many phenomena were speculated (hurricane-force winds, dust devils, slick algal films, thick sheets of ice), no one knew what caused the movement.
To solve the mystery, in 2011 a team of researchers led by paleobiologist Richard Norris, Scripps Institution of Oceanography, UC San Diego, began monitoring the rocks remotely. The research team fit 15 similar rocks with custom-built, motion-activated GPS units (the National Park Service disallowed use of native rocks) and installed a high-resolution weather station capable of measuring gusts to one-second intervals. Then — in what Ralph Lorenz of the Applied Physics Laboratory at the Johns Hopkins University suspected would be “the most boring experiment ever” — the researchers waited for something to happen.
In December 2013, Richard Norris and co-author and cousin Jim Norris discovered that the playa was covered with a pond of water three inches deep. Shortly after, the rocks began moving.
“Science sometimes has an element of luck,” Richard Norris said. “We expected to wait five or ten years without anything moving, but only two years into the project, we just happened to be there at the right time to see it happen in person.”
Their observations show that moving the rocks requires a rare combination of events. First, the playa fills with water, which must be deep enough to form floating ice during cold winter nights but shallow enough to expose the rocks. As nighttime temperatures plummet, the pond freezes to form thin sheets of “windowpane” ice, which must be thin enough to move freely but thick enough to maintain strength. On sunny days, the ice begins to melt and break up into large floating panels, which light winds drive across the playa, pushing rocks in front of them and leaving trails in the soft mud below the surface.
“On December 21, 2013, ice breakup happened just around noon, with popping and cracking sounds coming from all over the frozen pond surface,” said Richard Norris. “I said to Jim, ‘This is it!’”
The rocks moved under light winds of about 3-5 meters per second (10 miles per hour) and were driven by ice less than 3-5 millimeters (0.25 inches) thick, a measure too thin to grip large rocks and lift them off the playa, which several papers had proposed as a mechanism to reduce friction. Further, the rocks moved only a few inches per second (2-6 meters per minute), a speed that is almost imperceptible at a distance and without stationary reference points.
“It’s possible that tourists have actually seen this happening without realizing it,” said Jim Norris. “It is really tough to gauge that a rock is in motion if all the rocks around it are also moving.”
Individual rocks remained in motion for anywhere from a few seconds to 16 minutes. In one event, the researchers observed rocks three football fields apart began moving simultaneously and traveled over 60 meters (200 feet) before stopping. Rocks often moved multiple times before reaching their final resting place. The researchers also observed rock-less trails formed by grounding ice panels — features that the Park Service had previously suspected were the result of tourists stealing rocks.
“The last suspected movement was in 2006, and so rocks may move only about one millionth of the time,” Lorenz said. “There is also evidence that the frequency of rock movement, which seems to require cold nights to form ice, may have declined since the 1970s due to climate change.”
The team’s findings were published in the journal PLOS ONE on August 27.
A GPS station in the Inyo Mountains, Calif. Credit: Shawn Lawrence, UNAVCO.
A network of GPS stations in the western United States is revealing the severity of the drought in that region.
Compared to the nine years before the drought, the GPS data show that the western United States has lost 240 gigatons of water, which is enough to flood the entire region in 10 centimeters of water.
Investigating ground positioning data from GPS stations throughout the west, researchers at the Scripps Institution of Oceanography at the University of California, San Diego, found that the water shortage is causing an uplift effect up to 15 millimeters (more than half an inch) in California’s mountains and on average four millimeters (0.15 of an inch) across the west.
Results of the study, which was supported by the U.S. Geological Survey (USGS), appear in the August 21 online edition of the journal Science.
The measurements have a much better resolution — 200-300 kilometers — than data provided by NASA’s GRACE satellites, which shows how the water mass has changed on and below the Earth’s surface.
A dry riverbed in California.
Researchers Adrian Borsa, Duncan Agnew, and Dan Cayan used data from more than 700 GPS stations in the National Science Foundation’s Plate Boundary Observatory to measure the rising and falling of Earth’s surface due to the presence of water. Water in lakes or aquifers weighs down on the Earth causing the surface to sink, while during a drought the surface rises. Each station provides time and position information that is used to calculate the station’s location to within 1-2 millimeters horizontally and 3-5 millimeters vertically.
The current drought began in 2012, when data shows that in general, the ground rose by about four millimeters. The rise in the Sierra Nevada mountain range was 15 millimeters.
While poring through various sets of data of ground positions from highly precise GPS stations within the National Science Foundation’s Plate Boundary Observatory and other networks, Borsa, a Scripps assistant research geophysicist, kept noticing the same pattern over the 2003-2014 period: All of the stations moved upwards in the most recent years, coinciding with the timing of the current drought.
Agnew, a Scripps Oceanography geophysics professor who specializes in studying earthquakes and their impact on shaping the earth’s crust, says the GPS data can only be explained by rapid uplift of the tectonic plate upon which the western U.S. rests (Agnew cautions that the uplift has virtually no effect on the San Andreas fault and therefore does not increase the risk of earthquakes).
For Cayan, a research meteorologist with Scripps and USGS, the results paint a new picture of the dire hydrological state of the west.
“These results quantify the amount of water mass lost in the past few years,” Cayan said. “It also represents a powerful new way to track water resources over a very large landscape. We can home in on the Sierra Nevada mountains and critical California snowpack. These results demonstrate that this technique can be used to study changes in fresh water stocks in other regions around the world, if they have a network of GPS sensors.”
The study was supported by USGS National Earthquake Hazards Reduction Program.
Trimble has introduced an integrated GNSS reference receiver, broadband seismic recorder and a force-balance triaxial accelerometer for infrastructure and precise scientific applications.
The Trimble SG160-09 SeismoGeodetic system provides real-time GNSS positioning and seismic data for earthquake early warning and volcano monitoring as well as infrastructure monitoring for buildings, bridges, dams, as well as other natural and manmade structures.
The Trimble SG160-09 SeismoGeodetic system combines the innovation, reliability and data integrity of both the Trimble and REF TEK brands into a single instrument, Trimble said. The system integrates seismic recording with GNSS geodetic measurement in a single compact, ruggedized package. It includes a low-power, 220-channel GNSS receiver powered by the latest Trimble-precise Maxwell 6 technology and supports tracking of both GPS and GLONASS signals plus the Galileo E1 frequency.
The system includes both the SG160-09 and utilization of Trimble’s CenterPoint RTX correction service, which provides on-board GNSS point positioning. Based on Trimble RTX technology, the service utilizes satellite clock and orbit information delivered over cellular networks or Internet Protocol (IP), allowing cm-level position displacement tracking in real-time anywhere in the world. The SG160-09 system will be available for purchase without the RTX correction service for those applications using real-time kinematic (RTK) positioning.
The seismic recording sensor includes an ANSS Class A, low-noise, force-balance triaxial accelerometer with the latest, low-power, 24-bit A/D converter, which produces high-resolution seismic data. The internally built accelerometer has +/- 4g full scale output, large linear range, high resolution and sensitivity, which makes it ideal for both portable and permanent deployment. The SG160-09 processor acquires and packetizes both seismic and geodetic data and transmits it to system operators using an advanced, error-correction protocol with back-fill capability providing data integrity between the field and the processing center.
The SG160-09 system is ideal for earthquake early warning studies and other hazard mitigation applications, such as volcano monitoring, building, bridge and dam monitoring systems. The SG160-09 system features a variable size industrial grade USB drive to support real-time telemetry data transmission. In the event of a telemetry link outage, the data is stored on the USB drive and can be re-transmitted to the centralized processing station as soon as the communication link comes back up, allowing no data loss during the system operation.
The Trimble SG160-09 system is optimized for field use with instrument mounted or externally mounted GNSS antenna configurations. The lightweight yet rugged SG160-09 consumes very little power and can be used for projects with remote connectivity and in extreme weather conditions. Because the SG160-09 combines both GNSS and strong motion in a single instrument, site installation time is reduced, data communications flow through a single pathway, and station power infrastructure is streamlined, making the SG160-09 a cost competitive solution compared to other systems on the market today. It has an IP67 rating, which means it is sealed against dust and can be submerged in water up to a meter for approximately 30 minutes. The SG160-09 also meets MIL-STD 810F standard for drops, vibration and temperature extremes.
“The SG160-09 is another example of Trimble’s on-going focus in GNSS and seismic technology for the scientific and engineering communities,” said Ulrich Vollath, general manager for Trimble’s Infrastructure Division. “Trimble has developed a combined state-of-the-art GNSS receiver with a high-dynamic range, low-noise accelerometer that provides dynamic monitoring with the flexibility required for today and tomorrow’s challenges.”
The Trimble SG160-09 SeismoGeodetic system is expected to be available in the fourth quarter of 2014.
The 8th annual Institution of Geospatial and Remote Sensing Malaysia (IGRSM) International Conference and Exhibition on Geospatial & Remote Sensing will be held April 13–14 in Kuala Lumpur, Malaysia, supporting organizer Science & Technology Research Institute for Defence (STRIDE) announced in a news release. The conference, themed “Geospatial on the Go,” is aimed at disseminating knowledge and sharing expertise in geospatial sciences in all aspects of applications. It also aims to build linkages between local and international professionals in this field with industries, STRIDE said.
