nasa gnss applications & geosciences ruth e. neilan jet propulsion laboratory california...
TRANSCRIPT
NASA GNSS Applications
& Geosciences
Ruth E. Neilan
Jet Propulsion Laboratory
California Institute of Technology
International GNSS Central Bureau
Pasadena, CAMunich GNSS Summit
March 8, 2007
Overview
• Early NASA role in GPS - historical perspective• GNSS for Geodesy and Geosciences• International GNSS Service (IGS)• Some photos of IGS stations• AFREF - Unification of African Reference Frames • Global Geodetic Observing System (GGOS)• Contact Info
Rear Admiral John D. Bossler, &Charles.W. Chalstrom
“GPS Instrumentation and Federal Policy”, Proceedings, First International Symposium on Precise Positioning with the Global Positioning System,
Vol. 1, Rockville, MD, May 1985
GPS Policy Affects Civil Use - 1980
PNT Policy Today: Space Based Position Navigation and Timing, December 2004
Geodesy: MeasurementOf the Earth and its
Potential Fields
IONOSPHEREIONOSPHEREOCEANSOCEANS SOLID EARTHSOLID EARTH
ATMOSPHEREATMOSPHERE
Significantwave heightSignificant
wave height
Ocean geoid andglobal circulationOcean geoid andglobal circulation
Surface windsand sea state
Surface windsand sea state
Short-term eddyscale circulationShort-term eddyscale circulation
OCEANSOCEANS
High resolution 3Dionospheric imagingHigh resolution 3D
ionospheric imaging
Ionospheric struc-ture & dynamics
Ionospheric struc-ture & dynamics
Iono/thermo/atmo-spheric interactionsIono/thermo/atmo-
spheric interactions
Onset, evolution& prediction ofSpace storms
Onset, evolution& prediction ofSpace storms
TIDs and globalenergy transportTIDs and globalenergy transport
Precise ion cal forOD, SAR, altimetryPrecise ion cal forOD, SAR, altimetry
IONOSPHEREIONOSPHERE
Climate change &weather modelingClimate change &weather modeling
Global profiles of atmosdensity, pressure, temp,and geopotential height
Global profiles of atmosdensity, pressure, temp,and geopotential height
Structure, evolutionof the tropopause
Structure, evolutionof the tropopause
Atmospheric winds,waves & turbulenceAtmospheric winds,waves & turbulence
Tropospheric watervapor distribution
Tropospheric watervapor distribution
Structure & evolutionof surface/atmosphere
boundary layer
Structure & evolutionof surface/atmosphere
boundary layer
ATMOSPHEREATMOSPHERE
Earth rotationPolar motion
Earth rotationPolar motion
Shape and defor-mation of Earth
Shape and defor-mation of Earth
Location & motionof the geocenter
Location & motionof the geocenter
Gross massdistributionGross massdistribution
Structure, evolution of the deep interior
Structure, evolution of the deep interior
Precise globalreference framePrecise global
reference frame
SOLID EARTHSOLID EARTH
Geoscience thru GNSS
International GNSS ServiceFormerly the International GPS Service
Graph courtesy Analysis Coordinator G. Gendt, GFZ Potsdam
IGS Reference FrameTiming and Precise Clocks GLONASS Pilot Service ProjectIonosphere WG
GNSS: Global Navigation Satellite System
The IGS is a voluntary federation of more than 200 worldwide agencies in more than 80 countries that pool resources and permanent GPS station data to generate precise GPS products.
Over 350 permanent tracking stations operated by more than 100 worldwide
agencies comprise the IGS network. Currently the IGS supports two GNSS:
GPS and the Russian GLONASS.
IGS products are formed by combining independent results from each of several Analysis Centers. Improvements in signals and computations have brought the centers’ consistency in the Final GPS satellite orbit calculation to ~ 2cm.
http://igscb.jpl.nasa.gov
Many earth science missions and measurements, and multidisciplinary applications, rely upon the openly-available IGS products such as ephemerides and coordinate time series.
Atmosphere WGSea Level - TIGA ProjectReal-Time WGData Center WGGNSS WG
GPS Applications in IGS Projects & Working Groups
IGS 101International GNSS Service
• Recognized as an international scientific service– Advocates an open data policy, equal access
• Mission statement: ‘… IGS provides the highest-quality GNSS data and products in support of the terrestrial reference frame, Earth rotation, Earth observation(s) and research, positioning, navigation and timing and other applications that benefit society….’ , Recent strategy planning meetings, December 2006.
• Name change GPS - GNSS in 2005 reflects incorporation of GLONASS and interest in incorporating Galileo
• Highest accuracy GPS & GLONASS satellite orbits available anywhere – -3-5 cm 3-d wrms GPS – ~25-30cm GLONASS– mm-level station positions and velocities
• Network of over 350+ stations precision geodetic receivers produce GPS data on a continuous basis – ~ 35 also track GLONASS – ~100 report hourly– Sub-network moving towards real-time for upcoming pilot project
Photo courtesy of D. Stowers, JPL
Classic IGS station: short pillar monument, choke ring antenna, desirable VLBI co-location
(Pie Town, NM)
Photo courtesy ESA/ESOC Think you can solve for the snow depth from this station’s data? (Kiruna, Sweden)
Photos courtesy F.B. Madsen, DNSC
Relocating a station to a better monumented spot (Thule, Greenland)
• Fundamental point of departure for projects, services or products requiring geo-spatial information is a uniform & reliable co-ordinate reference frame.
• Over 50 countries in Africa each with their own system and frame and some with 2 or more systems.
• Although many areas are in conflict there are also areas where peace has been restored and require a lot of development.
• Many private commercial enterprises are setting up own reference frames particularly in the oil industry.
AFREF is an African initiative to unify reference frames based on the ITRF through a network of GNSS / GPS base stations at spacing such the users will be at most within ~1000 km of a base station.IGS is very engaged in the support and dedicated to the success of AFREF since 2000.
AFREF Planning
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Cairo, Egypt, 2005 Planning Call for Participation
Cape Town, South Africa, July 2006, 1st Technical Workshop
Catch the Earth!GGOS is a program of the International
Association of Geodesy (IAG):
• Ensures observations of the three fundamental geodetic observables and their variations: Earth's shape, gravity field and rotational motion
• Integrates different geodetic techniques, models, and approaches to ensure long-term, precise monitoring of observables in agreement with the Integrated Global Observing Strategy (IGOS)
• Is a recognized member of the Global Earth Observing System of Systems (GEOSS)
• Is a powerful tool consisting mainly of high quality services (e.g., IGS), standards and references, and of theoretical and observational innovations
Contact Information
Ms. Ruth E. NeilanInternational GNSS Service Central BureauJet Propulsion LaboratoryMS 238-5404800 Oak Grove Drive, Pasadena, CA 91109-8099USAtel: 818-354-8330fax: [email protected]
Part of this work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National
Aeronautics and Space Administration.
Back-up Charts
GRACE (Mar 2002)
CHAMP (Jul 2000)
SAC-C (Nov 2000)
JASON-1 (Dec 2001)
ICESat (Jan 2003) COSMIC (2005)
• GPS Flight Receiver
• NRC Decadal Study notes GPS to fly on board all 35 recommended missions (January 2007)
• LEO Missions Objectives/ Science Goals include:
– Atmospheric remote sensing
– Gravity, Magnetics
– Ionospheric remote sensing
– Ice and oceans
GPS Precise Navigation - Low Earth Orbiters
IGS GLONASS Tracking Network and Final Orbit Comparisons
WHY IGS? Historical notes
– Geodynamics, geodetic, and space agency organizations realized the potential of GPS by late 1980’s
– Motivating goal: millimeter positioning in support of science & engineering anywhere in the world
– No single agency can or should assume the capital investment & recurring operations costs for the entire infrastructure
– Join with key international partners to form federation, define cooperation, set standards, driven by science quality
– Global framework for virtually all regional & national networks – Implement a global civilian GPS tracking system for science and
research– Participants are enthusiastic!– Later, more products (tropospheric, ionospheric…) from the same
rich data set
Network coordination
Cycle slips x1000/observationsThe CB has developed automated methods to…
Use Change Point Analysis to detect unreported changes or degrading equipment
Cycle slips x1000/observations
And compare an IGS site against all the others in mean and standard deviation of several data quality monitoring measures