STK Helps NASA's Chandra Explore the Universe - AGI

STK Case StudySTK Helps NASA’s ChandraExplore the Universe“If we were to developthese kinds of tools, it wouldtake years and millions of dollars.Why reinvent the wheel?”Dan ShropshireChandra Mission Planning LeadTRW, Inc.

Chandra ObservatoryDetects Sources 20 TimesFainter Than Any PreviousX-ray Telescope‘‘We could see and determineso many things with STKthat we couldn’t conceptualizewith just the numbers.”Dan ShropshireChandra Mission Planning LeadTRW1 100 10,000 10 million 10 billiondegree K degrees K degrees K degrees K degrees KRadio Microwave Infrared Visible UV X-raysLightGammaRays0.5 50 0.5 1 0.0005centimeters microns microns nanometer nanometerWAVELENGTHNote: degrees Kelvin (K) = degress Celsius (C) + 273X-rays are created by temperatures at millions of degrees Celsiusas shown in the above electromagnetic spectrum.The images are spectacular: a glowing cosmiccrossbow; a cool-green galaxy caught cannibalizinganother; and an iridescent purple mushroomcloud shrouding the heart of a rapidlyspinning neutron star.Photographs like these have been inspiring astronomers sincethe launch of NASA’s Chandra X-ray Observatory in July1999. Capturing rays that can’t be seen on Earth by the humaneye or conventional optical telescopes, this space-basedobservatory has provided conclusive proof of some long-heldscientific theories, given insight into the evolution of galaxies,and forced astronomers to take a new look at the universe.Chandra joins NASA’s past and present family of Earthorbitingobservatories, including the Hubble SpaceTelescope and the Compton Gamma Ray Observatory. Ithouses the world’s premier X-ray telescope, which recordsdistant images eight times sharper and detects X-raysources 20 times fainter than any X-ray telescope before it.According to NASA scientists, its resolving power—0.5arc-seconds—would be equivalent to a person reading astop sign from 12 miles away or comprehending anaverage-sized newspaper headline from a distance of a halfmile. Capturing these images is a special high-resolution,cylindrical mirror assembly that houses the largest andsmoothest mirrors of their kind ever created. IncomingX-rays, which would penetrate normal mirrors, graze offtwo sets of four nested mirrors and are channeled into aninstrument section for detection and study. The largest ofthe eight is almost 4' in diameter and 3' long. Together, themirror group weighs more than a ton.Managed by NASA’s Marshall Space Flight Center inHuntsville, AL, Chandra is one of the largest and heaviestpayloads the Space Shuttle has launched. The Harvard-Smithsonian Astrophysical Observatory’s Chandra X-rayCenter (CXC) in Cambridge, MA, manages the Chandrawww.stk.com

Aspect camera stray light shadeSunshade DoorSpacecraft ModuleSolar Array (2)Optical BenchHigh ResolutionMirror Assembly(HRMA)Thrusters (4)Low Gain Antenna (2)TransmissionGratings (2)CCD Imaging Spectrometer (ACIS)High resolutioncamera (HRC)IntegratedScienceInstrumentModule(ISIM)The Chandra X-ray Observatory has three basicassemblies: the spacecraft, telescope, and thescience instrument panels.An STK two-dimensional map traces Chandra’s groundtrack as it moves in its orbit.Chandra captured this imageof the compact nebula aroundthe neutron star Vela Pulsar.NASA’s most powerful X-ray telescope circles the globe in a highly ellipticalorbit, gathering images of the universe and sending them back to Earth.science program and controls the observatory for NASA.TRW Space and Electronics Group of Redondo Beach,CA, leads the contractor team that built Chandra and managesflight operations in Cambridge.According to industry experts, Chandra has opened a newwindow for astronomers into the universe of high-energycosmic events such as pulsars, supernova remnants, andblack holes. Scientists are now able to create spectacularlydetailed images of celestial phenomena whose mere existencethey could only hypothesize before.STK’s Role in the MissionSatellite Tool Kit® (STK) was used extensively during themission’s design and development stage and played a crucialrole in transfer-orbit operations. “We are extremely pleasedwith the level of involvement that STK has had with such aprestigious mission,” says Joe Murphy, STK product managerat Analytical Graphics, Inc. (AGI). “This telescope willhelp scientists probe even deeper into the mysteries of space.The fact that the Chandra team chose STK for so manyaspects of this historic mission shows the versatility andtrusted precision of the software.”TRW’s Mission Planning group maps out all of Chandra’sobservations, working directly with the science communityto schedule a list of observations, build the commandloads for the observation sets, and hand those off to thecontrollers for uplink. The group also handles the flightdynamics portion of the work, which includes calculatingall the orbital elements, plots of access times to the groundstations, eclipse times, and all attitude determination. “Weused STK to predict start and stop times of eclipses basedon the position of the spacecraft and compared those timesto when the coarse sun sensor current output declined,”says TRW mission planning lead Dan Shropshire.STK/PRO® and STK/Advanced VO were integrated aspart of the original ground system to do real-time visualization.The STK software suite was later expanded withthe addition of other modules, including STK/Astrogator®and STK/Comm. STK/Advanced VO provides 3-Dwww.stk.com

epresentation of the satellite and surrounding environment,including real-time dynamic display of satelliteposition and altitude display for operations. STK/Commperforms communications analysis such as link margins tocompare real-time performance with predicted values.STK/PRO is also used to calculate many different types ofmission data, including ground-station visibility andeclipse-time calculations.The MathWorks’MATLAB® interfaces with STK to generatereports such as percent occultation, angle of the sunto the array, and angle of Earth to the back side of the arrayfor power analyses. STK/PRO’s High Precision OrbitPropagator (HPOP) generates external ephemeris files thatare exported to MATLAB tools for additional processingand analysis.The Benefits of COTSMany organizations can no longer afford to developmission-specific software in-house. Commercial satellitesoftware that can be used for multiple missions is playinga growing, cost-saving role in enabling successful andeconomical space activities. Commercial off-the-shelf(COTS) software, such as STK, that is stable, accurate,and well-supported is key in all phases of a satellite’slife—from pre-launch analyses to ground support duringoperations through graveyarding.“We could see and determine so many things with STK thatwe couldn’t conceptualize with just the numbers,” explainsShropshire. “If we were to develop these kinds of tools, itwould take years and millions of dollars. Why reinvent thewheel?” Shropshire says a good example of that came whenNASA-Select television broadcast an STK simulation ofone of the burns, which was a shining moment for the team.COTS software has also proven that it has the technicaldepth and diversity of capabilities to handle risky situationswhere new ground is broken. This increasing reliance onCOTS solutions demands better and more robust productsthat can address a wide variety of analysis and planningneeds. Users are looking for an economical solution that istechnically accurate and easy to use. STK is that COTSsolution for tens of thousands of aerospace professionals.Mission planning lead Dan Shropshire discusses using STK inattitude maneuvers with operations personnel Paul Levit, left, andKen Gage.‘‘The fact that the Chandra teamchose STK for so many aspectsof this historic mission showsthe versatility and trustedprecision of the software.”Joe MurphySTK Product ManagerAnalytical Graphics, Inc.STK/Advanced VO attitude sphere and vectors provide visual cuesfor Chandra system engineers as they plan attitude maneuvers.www.stk.com

AGI Donates Softwareto Students to PromoteChandra MissionIn addition to working with the Chandra mission team,AGI also helped astronomy students at the Stephen WhiteMiddle School of Carson, CA, better understand the missionand actually become part of it. By supplying theschool with STK software through its EducationalAlliance Program, AGI gave students in the eighth gradethe opportunity to run the same simulations and scenariosthat were being implemented at NASA.Started five years ago by science teacher Wayne Johnson,the astronomy class attended the Chandra launch at CapeCanaveral, FL, on July 23, 1999. The group was able to doso through funding by sponsors British Petroleum/ARCOand Southwest Airlines.According to Johnson, the teenagers took AGI’s software andwent light years, educationally. Earlier in 1999, the classentered a science fair where one judge was a lieutenant generalin the U.S. Air Force. “He asked them questions aboutSTK and how they had used it to develop their project,” saysJohnson. “He couldn’t believe their answers and was amazedthat they had mastered it and understood the terminology.”Paul Graziani, AGI President and CEO, shares Johnson’senthusiasm. “The energy and excitement that thesestudents have for the space program underscores why AGIsupports academia,” says Graziani. “By giving youngpeople access to aerospace analysis and visualizationsoftware like STK, we are giving them an opportunity togain a deeper insight into space. For us, the prospect ofcontributing to the future of the industry is exciting.”Says Johnson, “Companies such as AGI allow educators tostart training the next generation of aerospace professionals atan early age. AGI should be applauded for the resources it hasused to support our program and others like it across thenation.” Over the years, AGI has donated in excess of $325million worth of commercial software through its EducationalAlliance Program. The Stephen White Middle School hasreceived software with a value of more than $300,000.Wayne Johnson’s astronomy studentsat the Stephen White Middle Schoolof Carson, CA, used STK software torun the scenarios used by NASA inthe Chandra mission.‘‘Companies such as AGI alloweducators to start training the nextgeneration of aerospaceprofessionals at an early age.”Wayne JohnsonStephen White Middle Schoolwww.stk.com

About AGIAnalytical Graphics, Inc. (AGI), headquartered in TheCommons at Great Valley near Philadelphia, PA, providescommercial off-the-shelf (COTS) analysis and visualizationsoftware solutions to more than 25,000 aerospaceindustry professionals through its core product STK and aseries of specialized STK add-on modules. STK supportsaerospace systems from mission planning through onorbitoperations and is free to the aerospace community.Independently validated and verified, the STK softwaresuite goes to market via an experienced product development,marketing, and sales team with a solid focus onunderstanding customer needs then supporting thoseneeds with current and expanding STK capabilities. Basicsoftware applications include calculating and visualizinga vehicle’s position and attitude, determining acquisitiontimes, and analyzing the vehicle’s field of view. The keyfunctions of STK can be extended with add-on modulesthat support specialized analyses including collisionavoidance, detailed communication link analysis, realtimevisualization, orbit determination, maneuver planning,coverage assessment, and missile systems readinessand deployment.For more information about AGI, the STK software suite,or how to obtain a free copy of STK on CD-ROM, call800.220.4785 or 610.981.8000, e-mail info@agi.com, orvisit www. agi.com.Andromeda GalaxyThe blue dot in the lower right quadrant of thisimage is found in the central portion of theAndromeda Galaxy and is the location of ablack hole with the mass of 30 million suns.Image: NASA/SAO/S. MurrayCrab NebulaAt the center of this nebula in the constellationof Taurus is a rapidly spinning neutronstar that emits pulses of radiation 30 timesa second.Image: NASA/CXC/SAOEta CarinaeEta Carinae is a massive star 7,500 light yearsfrom Earth. The outer horseshoe-shaped ringhas a temperature of about 3 million degreesCelsius; the blue cloud is much hotter, and thewhite spot may contain the superstar.Image: NASA/CXC/SAOVela PulsarThis nebula, found in the Vela supernova remnant,is created as a rapidly rotating neutronstar spins out jets of high-energy particleswhile moving through the remnant.Image: G.G. Pavlov, G.P. Garmireand D. Sanwal (PSU)©2001 Analytical Graphics, Inc.All copyrights, trademarks, and registered trademarks are the property of their respective owners. Analytical Graphics®, Analytical Graphics, Inc., Satellite Tool Kit®(STK), STK/PRO®, STK/VO®, STK/Advanced VO, STK/Astrogator®, STK/CAT, STK/Chains, STK/Comm, STK/Connect, STK/Coverage, STK/DIS®,STK/GIS®, STK/High Res Maps, STK/PL®, STK/PODS, STK/Radar, STK/Radar Advanced Environment, STK/Server®, STK/Space Environment,STK/Terrain, STK/VO Earth Imagery®, and STK/WebCast are trademarks of Analytical Graphics, Inc. MATLAB® is a registered trademark of The MathWorks, Inc.Face of the Earth Imagery is copyrighted and used courtesy of ARC Science Simulations, Inc. Electromagnetic spectrum diagram on page two courtesy of the Harvard-SmithsonianCenter for Astrophysics. Chandra schematic on page three courtesy of NASA, United Space Alliance, and The Boeing Company. Chandra mission team photos by William S. Davis.GENERAL INFO & SALESPhone: 1.800.220.4785*1.610.981.8000E-mail: info@agi.comTECHNICAL SUPPORTPhone: 1.888.785.9973*1.610.981.8888E-mail: support@agi.com*Toll-free in U.S. & Canada