NASA Technical Reports Server (NTRS) 20000116404: Advanced Concepts, Technologies and Flight Experiments for NASA's Earth Science Enterprise

6 Pages·0.4 MB·English

by  NASA Technical Reports Server (NTRS)

AIAA 2000-5177
ADVANCED CONCEPTS, TECHNOLOGIES, AND FLIGHT EXPERIMENTS FOR NASA'S EARTH
SCIENCE ENTERPRISE
By
Barry D. Meredith
NASA Langley Research Center
Hampton, Virginia
ABSTRACT ATMOSPHERIC SCIENCE MISSION
Over the last 25 years, NASA Langley Research The Langley mission in atmospheric science is to
Center (LaRC) has established a tradition of excellence provide understanding of key atmospheric processes
in scientific research and leading-edge system and trends through a portfolio of space, aircraft, and
developments, which have contributed to improved ground-based measurements and atmospheric
scientific understanding of our Earth system. modeling, analysis, and prediction. Langley's
Specifically, LaRC advances knowledge of atmospheric leadership role in atmospheric science for ESE has been
processes to enable proactive climate prediction and, in achieved primarily by proactively identifying emerging
that role, develops first-of-a-kind atmospheric sensing issues, developing new measurement capabilities,
capabilities that permit a variety of new measurements conducting space-based measurements, developing
to be made within a constrained enterprise budget. predictive models, and leading international field
These advances are enabled by the timely development missions.
and infusion of new, state-of-the-art (SOA), active and
passive instrument and sensor technologies. In Specific areas of LaRC scientific research are:
addition, LaRC's center-of-excellence in structures and Water Cycle, Clouds, and Aerosols which includes
materials is being applied to the technological radiation budget and cloud modeling; tropospheric
challenges of reducing measurement system size, mass, chemistry addressing pollution/greenhouse gases
and cost through the development and use of space- sources, sinks, and transport; middle atmosphere
durable materials; lightweight, multi-functional science which includes energy balance, ozone
structures; and large deployable/inflatable structures. depletion, and chemistry/dynamics; and Aviation
NASA Langley is engaged in advancing these Impacts such as exhaust effects. Langley scientists have
technologies across the full range of readiness levels recorded significant scientific achievements in each of
from concept, to components, to prototypes, to flight these areas of research. An example is the development
experiments, and on to actual science mission infusion. of a comprehensive Earth radiation budget data set,
The purpose of this paper is to describe current including first cloud radiative forcing measurements.
activities and capabilities, recent achievements, and In addition, under the leadership of LaRC atmospheric
future plans of the integrated science, engineering, and scientists, the impact of anthropogenic emissions on
technology team at Langley Research Center who are global atmospheric chemistry and effectiveness of
working to enable the future of NASA's Earth Science Montreal Protocol were verified.
Enterprise.
The strength of the Langley approach to its
atmospheric science mission is the integration of
scientists, engineers, and technologists into productive
teams. From this collaborative teaming approach,
which also includes partnerships with industry, small
Copyright©2000bytheAmericanInstituteofAeronauticsand
Astronautics.Inc.NocopyrightisassertedintheUnitedStatesunder business, universities, other NASA centers, and other
Title 17,US. Code. TheU.S.Governmenthasaroyalty-freelicense government agencies, has come pioneering
toexerciseallrightsunderthecopyrightclaimedhereinfor
measurement capabilities. Examples include lidar
GovernmentalPurposes. Allotherrightsarereservedbythe
copyrightowner. measurements for high vertical resolution atmospheric
l
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aerosols and chemistry studies (LITE, LASE_ and solar There are two primary technology product areas at
occultation (SAM, SAGE. HALOE) and limb emission Langley which support the Earth Science Enterprise.
measurements (L[MS) for studies of stratospheric The instrument and sensor area features lasers/lidar
chemistry. In fact, a significant portion of all NASA technologies as well as passive electro-optic and
spaceflight atmospheric research instruments has been microwave sensors. Langley is known for its unique,
developed at Langley as shown in figure 1. world-class, end-to-end capability in [idar technology
and systems. The capability exists to address all phases
These developments have relied on a robust of development from the invention of new laser sources
research and technology development program at the to the development and deployment of a lidar science
center, which has successfully matured atmospheric instrument either in the field, in an aircraft or in space.
sensing technologies from concept to measurement LaRC scientists and engineers were the first to
system infusion. demonstrate an atmospheric quality lidar from space via
the Shuttle-based LITE mission in 1994. Another first
was the successful deployment of a fully autonomous,
differential absorption lidar in a high altitude ER-2
aircraft. The Langley R&T program has also enabled
new, more precise measurements of the Earth's
troposphere and stratosphere through the development
of advanced radiometer and spectrometer techniques
and technologies. Langley researchers were the first to
demonstrate a solar occultation sensor in space and
provided the first measurements of tropospheric trace
gas from space using gas filter correlation radiometry.
The second primary technology product area in the
Langley R&T program is structures and materials.
Much of the current effort here is focused on the
problems associated with large apertures where the
Figure 1. Atmospheric sensing at NASA Langley. objective is to accommodate high-resolution space-
based sensing systems in smaller, reduced-costs launch
RESEARCH AND TECHNOLOGY packages. This challenge draws on Langley expertise in
deployable and inflatable structures, breakthrough
The process for formulating the technology materials, structural dynamics and geometry control,
development program at LaRC features teams of and lightweight multifunctiona[ structures.
scientists, engineers, and technologists who merge
science-driven measurement requirements with Research and technology development in both the
instruments and sensors and structures and materials
advanced concepts and technology opportunities to
develop proposed research and technology development product areas encompasses all levels of technology
projects. These proposals must have direct linkage to maturation including conceptual development and
the ESE Strategic Plan and the Science Implementation analysis, component development and demonstration,
Plan and accommodate technology requirements found system/subsystem development and demonstration, and
in the ESE Capability Needs Database. ISO 9000 protoflight space validation. The following sections
procedures define an end-to-end proposal development provide selected examples of current activities at
process, which includes quality reviews, management Langley across the various levels of technology
endorsement, and a "lessons learned" feedback loop for maturity.
continuous improvement. The finished proposals are
LIDAR TECHNOLOGY DEVELOPMENT
then submitted in response to NASA Research
Announcements (NRA's) issued by programs that span
the range of technology readiness such as the ESE There are considerable technological challenges
Advanced Technology Initiative (components), associated with enabling lidar atmospheric
Instrument Incubator Program (systems and measurements from space. Principle among those is
subsystems), and the New Millennium Program obtaining adequate signal-to-noise measurements
(protoflights for space validation). within a compact, affordable system. To that end,
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technologdyevelopmenattsLaRCarefocuseodnhigh- Highoutpuet nergyfromthelasersourceisone
energy,high-efficiencyc,onductively-cooleladser methodforincreasinligdarrcturnsignalA. notheirsto
transmittersp,recisiondeployabletelescopesa,nd increastehesizeofthereceivearpertureR. esearcish
highlyefficiencydetectors.Sincetheoperating currentlyunderwayat Langleytodevelopcritical
wavelengthvsaryaccordintgothedesiredabsorption componenftosra3-metecrlassp,recisiondeployable
lineoftheatmosphersipcecietsobemeasure(dwater telescopeT.hedeployabfleeatureenabletshetelescope
vaporo,zonec,arbondioxidee,tc.);itisnecessatroy pre-deploymelanutnchpackagteobeaccommodaitned
literallyinventnewsolidstatelasersourceosperating asmall,lesscostlylaunchvehicle.Researchearts
fromtheultraviolettotheinfrared.Toassisitnthat LaRChavedevelopedprecisionlatchandhinge
effort,Langleytechnologishtsavedevelopeudnique mechanism(fsigure3) whichfeaturehighlylinear
quantummechanicmalodelingtoolsthatallowlaser operationwith minimumhysterisisto enablea
performancoefsolidstatecrystalstobepredicteidn deploymeanctcuracoyf2microns.
advancoefcommittintgohardwardeevelopmenAt.s
anexampleq,uantummechanicmalodelinagccurately
predictetdheperforman(cweavelengtehf,ficiencye,tc.)
ofthesolidstatemateria(hl olmiumandthuliumdoped
YLF)whichwasthenusedtodevelopaneye-safe,
2-microlnasefroracoherenwtindslidar.
Afterdetermininthgeappropriacthearacteristoicfs
thesolidstatemateriavliamodelinagndspectroscopy,
LaRCtechnologistws,orkingwithindustrypartners,
develoapbreadboalradsefrorlaboratorteysting.The
laseirsthencharacteriziendthelaboratorinytermsof
pulseformate,nergyperpulse(typically0.5to1.0J),
Figure3.Precisiolantchandhingedeployment
beamqualityl,aselrine-widtha,ndefficiencyI.nitially,
mechanisms.
forcostconsiderationthse,laseirspumpevdiaaflash
lamporanothelarser.Howevetro, achievtehedesired
Inadditionl,ightweighctompositme irrorpanels
efficiencyi,t musteventuallybetestedin a diode
havebeendevelopeudnderanSBIRwithComposite
pumpecdonfiguratio(nfigure2). Thesediodearrays
OpticsInc.(figure4)withanareadl ensityof100kg
aredevelopetdoLaRCspecificationosftenbysmall,
persquarmeeter.Currentlyth,eUniversitoyfColorado
innovativebusinesses.Langleyresearcherasre
is performingdynamicstestinganddeployment
currentlyinvestigatinngewpumpconfiguration(es.g.,
accuracayndrepeatabilitytestswithanintegrated
endpumpeddisks)in aneffortto improveoverall
panel/mechanaissmsesmbly.
transmitteerfficiencyA. ftersuccessfcuolmponeanntd
systemtestingthelab,thelasetrransmittdeervelopment
isattheappropriatsetageforenteringtheInstrument
IncubatoPrrogramwheremoreadvancefdieldand
aircrafdtemonstratiocannsbeperformed.
Figure2.Diode-pumpleadsetrransmitter. Figure4.Composimteirrorpanels.
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AmericaInnstitutoefAeronautiacnsdAstronautics
Onemajordriverforsucha"photoncollecting"
where SAGE Ill instruments would be mated with
telescopweouldbeanultravioledtifferentiaalbsorption
conventional spacecraft busses.
lidarforspace-basemdeasuremeonftstropospheric
ozone.
GAS AND AEROSOL MONITORING
SENSORCRAFT (GAMS)
Langley pioneered the atmospheric measurement
technique known as solar occultation dating back to the
first such measurement in space during the Apollo
Soyuz mission. Since solar occultation images the sun
through the Earth's atmosphere, the technique is self-
calibrating offering long-term stability. It also provides
high-vertical resolution measurements of the
stratosphere and upper troposphere. SAGE III is the
latest solar occultation instrument being developed to
measure ozone, aerosols, clouds, water vapor, and other
species. Multiple copies of SAGE III are under Figure 5. Gas and Aerosol Monitoring Sensorcraft
development for launch on a Russian Meteor spacecraft (GAMS).
and as a Space Station attached payload. The weakness
of this technique is coverage since there is only 2 After a successful 24-month component technology
measurement opportunities per orbit. It has been development effort at LaRC, the GAMS concept was
determined that 6 SAGE III instruments would have to
ready to enter the system/subsystem demonstration
be placed in the appropriate orbit to achieve weekly phase. In 1998, a GAMS proposal was selected by the
coverage of the Earth. Obviously, this fleet approach is ESE through an Instrument Incubator Program (liP)
affordable only if the launch costs, instrument/ competitive process. Consistent with the scope of the
spacecraft per copy development cost, and fleet liP, this effort focuses on the development and
operating cost can be kept to a minimum. The demonstration of those functions specific to the science
approach being pursued at Langley is to utilize instrument and flight data processing hardware and
advanced instrument and spacecraft technologies to software. In this particular case, itjust so happens that
develop compact, highly integrated "sensorcraft" where those functions had been judged to be the technical "tall
the boundary between the spacecraft bus and instrument poles" at an earlier design review.
become less distinct. Essentially, the sensorcraft
concept integrates the resource requirements of both to The IIP/GAMS project will develop and test a
minimize size, power consumption and cost. A fleet of novel two-axis gimbal system for spectrometer scan
intelligent sensorcraft constitutes the next generation of control and will integrate and test the grating
SAGE measurement capability and is referred to as Gas spectrometer and Digital Signal Processing (DSP)
and Aerosol Monitoring Sensorcraft or GAMS hardware and software subsystems. The integrated
(figure 5). spectrometer/DSP is currently undergoing
functional/performance laboratory and roof top testing.
The science mission envisioned for GAMS would Late in the year, a series of sunrise/sunset flight field
provide multi-wavelength aerosol extinction and full demonstrations will be conducted onboard NASA
03, O,, and H20 profile coverage over a spectral range LaRC's 757 at 42,000 feet. Several advanced
of 430 nm to 1020 nm. GAMS concept studies project technologies will be validated via the IIP/GAMS field
the sensorcraft volume to be about 0.1 cubic meters demonstrations. In addition to the DSP for onboard
with a mass of 50 Kg and power of 50 watts. Real data processing, these include a high-resolution, deep-
time, onboard data processing will be performed to well, CCD linear array, an advanced piezo-electric
produce EOS Level-2 science data at rate which can be motor drive for the two-axis gimbal, and a carbon-
down linked directly to a user's workstation over a carbon spectrometer head.
commercial LEO communications system. Studies
indicate that a GAMS fleet of 6 would offer a 65% cost Since the sensorcraft fleet approach to atmospheric
savings compared to the more traditional approach sensing is a radical departure from convention, it is
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likelytorequireactuavlalidatioinnspacebeforebeing
ENABLING THE EARTH SCIENCE VISION
acceptebdythelargersciencceommunityT.herefore,
subsequentot a successfuIIlP demonstratiotnh,e
The Earth Science Enterprise, through its Vision
developmeanntdoperatioonfafleetof2ormorefull-
Initiative (ESVI), looks to understand the Earth System
up,GasandAerosoMl onitoringSensorcrawftouldbe
and then go beyond understanding to the benefits
anidealflightexperimenfotrtheNewMillennium
derived from prediction of the Earth System. Proactive
Progra(mNMP).
environmental prediction would enable accurate two-
week weather forecasting, accurate climate prediction,
and prediction of natural hazards as examples. The
GEOSTATIONARY IMAGING FTS (GIFTS) ESE seeks to develop an architecture that connects and
focuses science, measurements, and technology
NASA Langley Research Center (LaRC), has investments toward realizing the benefits of these
teamed with University of Wisconsin-Madison, Space applications in the future.
Dynamics Laboratory (SDL) of Utah State University
and National Oceanographic and Atmospheric The R&T program at Langley is currently pursuing
Administration (NOAA) to develop a new measurement the reach goals established by the ESVI within four
concept known as Geostationary Imaging Fourier major technology themes: advanced sensors,
Transform Spectrometer (GIFTS). GIFTS was recently sensorwebs, information synthesis, and access to
selected by the New Millennium Program for knowledge. Under the advanced sensors theme,
development and space validation with launch Langley is developing advanced tunable lidar
scheduled in 2004 (figure 6). The imaging FTS is an technologies described in a previous section of this
innovative measurement technique for water vapor, paper. In addition, the structures and materials
temperature, and wind sounding that will provide expertise at LaRC is being applied to the challenges of
critical weather information not achievable through any developing large, ultra-lightweight, inflatable
existing space-based observatory. It is also capable of telescopes and antennas for high-resolution imaging
measuring the motion of clouds and transport pollutants and microwave radiometry.
in the atmosphere.
The sensorweb concept incorporates multiple,
reprogammable/reconfigurable, observational systems
operating collaboratively from multiple vantage points
(LEO, GEO, LI, etc.) to provide a robust and adaptive
earth observing network. However, for this concept to
be feasible, observational nodes on the sensorweb must
be low cost, autonomous, and intelligent,
micro/nanosatellites. Developments to date at Langley
in the GAMS R&T project are intended to enable a
"smart" sensorcraft capability for Earth Science.
Therefore, GAMS can be viewed as an initial step
toward realizing the sensorweb concept. A logical next
Figure 6. GIFTS instrument on a Geostationary step would be a NMP space flight experiment featuring
satellite. multiple, collaborative sensorcraft at various orbital
locations.
In addition to the demonstrating an advanced
measurement technique, several technologies will be The EOS Distributive Active Archive Center
flight tested and validated in the NMP GIFTS mission. (DAAC) for tropospheric chemistry, radiation budget,
These include 2-D imaging arrays, active cooling, fast clouds and aerosol data resides at Langley Research
digital signal processing, pointing and control, radiation Center. Consistent with capabilities identified by the
protection, and lightweight materials. GIFTS ESVI for access to knowledge, the DAAC has
represents a first step toward incorporating developed a system called the Langley TRMM
technological breakthroughs into the next generation of Information System (LaTIS). Specifically, this system
operational weather observing systems. deals with high volume satellite data production,
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archive, and distribution. To support early data fusion atmosphere. LaRC possesses a unique end-to-end
work, a facility known as Cave Automated Virtual capability to go from the scientific question to mission
Environment (CAVE) has been built to support development to data analysis. The cornerstone of this
research into how to benefit from immersive capability is a robust research and technology program
environments for 3-dimensional visualization of geo- which spans the technology readiness levels from
spatial data sets. concept to component development to system
prototypes to flight validation. The strength of the
SUMMARY Langley R&T approach is an integrated team of
scientists, engineers, and technologists working
NASA Langley has over 20 years of experience in together to achieve science-driven, technological
spaceflight, airborne, and ground-based scientific innovation. The focus is on reducing cost and enabling
measurements. These measurements have contributed new measurements for the next generation EOS
significantly to our understanding of the Earth's missions and the realization of the Earth Science vision.
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