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Grail launch

  1. 1. Press Kit/AUGUst 2011Gravity Recovery and InteriorLaboratory (GRAIL) Launch
  2. 2. Media ContactsDwayne Brown Policy/Program 202-358-1726NASA Headquarters, Management dwayne.c.brown@nasa.govWashington, DCDC Agle GRAIL Mission 818-393-9011Jet Propulsion Laboratory, agle@jpl.nasa.govPasadena, Calif.Caroline McCall Science Investigation 617-253-1682Massachusetts Institute of cmccall5@mit.eduTechnology,Cambridge, Ma.Gary Napier Spacecraft 303-971-4012Lockheed Martin Space Systems, gary.p.napier@lmco.comDenver, Colo.George Diller Launch Operations 321-867-2468Kennedy Space Center, george.h.diller@nasa.govCape Canaveral, Fla.For more information
  3. 3. ContentsMedia Services Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Quick Facts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Why GRAIL? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Mission Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Mission Phases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Spacecraft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17Why Study Gravity?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Science Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Science Team . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Missions to the Moon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24NASA’s Discovery Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Program/Project Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27GRAIL Launch 3 Press Kit
  4. 4. GRAIL Launch 4 Press Kit
  5. 5. Media Services InformationNASA Television Transmission News ConferencesIn continental North America, Alaska and Hawaii, Two GRAIL pre-launch news conferences will be heldNASA Television’s Public, Education, Media and HD at the Kennedy Space Center Press Site. The GRAILchannels are MPEG-2 digital C-band signals carried “mission” news conference will be held on Sept. 6,by QPSK/DVB-S modulation on satellite AMC-3, 2011, at 1 p.m. EDT. The second, the GRAILtransponder 15C, at 87 degrees west longitude. “science” news conference, will be held on Sept. 7,Downlink frequency is 4000 MHz, horizontal 2011 at 10 a.m. EDT. The news conferences will bepolarization, with a data rate of 38.86 MHz, symbol televised on NASA TV.rate of 28.1115 Ms/s, and 3/4 FEC. A Digital VideoBroadcast (DVB) compliant Integrated Receiver Launch StatusDecoder (IRD) is needed for reception. Note: Effective Recorded status reports will be available beginningWednesday, Sept. 1, 2010, at 2 p.m. Eastern, NASA two days before launch at 321-867-2525 and 301-TV is changing the primary audio configuration for 286-NEWS.each of its four channels to AC-3, making eachchannel’s secondary audio MPEG 1 Layer II. Internet InformationFor digital downlink information for NASA TV’s Media More information on the GRAIL mission, includingChannel, access to NASA TV’s Public Channel on an electronic copy of this press kit, news releases,the web and a schedule of programming for GRAIL status reports and images, can be found at http://activities, visit and CredentialingNews media representatives who wish to cover theGRAIL launch must contact NASA/Kennedy SpaceCenter Public Affairs in advance at 321-867-2468.GRAIL Launch 5 Press Kit
  6. 6. Quick FactsMission Name Second Stage:GRAIL is an acronym for Gravity Recovery And — Aerojet AJ10-118K second stage engineInterior Laboratory. — Burns Aerozine-50 and nitrogen tetroxide oxidizer — Vacuum-rated thrust: 9,645 poundsSpacecraft Launch Site: Space Launch Complex 17B, CapeThe two spacecraft (GRAIL-A and GRAIL-B) are Canaveral Air Force Station, Fla.mirror twins. GRAIL Mission Milestones and DistancesStructure TraveledMain structure: 3.58 feet (1.09 meters) high, 3.12 feet(0.95 meters) wide, 2.49 feet (0.76 meters) deep Launch period: Sept. 8 – Oct. 19, 2011 (42 days).Power Launch location: Pad SLC-17B, Cape Canaveral AirTotal solar array power at 1 AU: 763 watts Force Station, Fla. Moon Arrival Date:Power: Four panels of silicon solar cells mounted on GRAIL-A: Dec. 31, 2011satellite’s top and side exterior surfaces GRAIL-B: Jan. 1, 2012Batteries: 10 nickel-hydrogen cells providing up to Science Orbit Altitude: 34 miles (55 kilometers)16 amp-hours of 28-volt power The distances travelled by GRAIL-A and GRAIL-BInstruments to the moon are similar but not the same. Also, theMicrowave ranging instrument, accelerometer, star distance travelled to the moon changes (decreases)camera as a function of launch date. The distance the spacecraft will have travelled for a Sept. 8 launchMass is much larger than the distance travelled on anLaunch: 677 pounds (307 kilograms) Oct. 19 launch.Dry: 443 pounds (201 kilograms)Fuel/He: 234 pounds (106 kilograms) Distance travelled to the moon (launch to lunar orbit insertion) for a launch on Sept. 8:Launch Vehicle GRAIL-A = 2,594,378 miles (4,175,246 kilometers) GRAIL-B = 2,663,793 miles (4,286,959 kilometers)Type: Delta II 7920H-10C (also known as a Delta IIHeavy) Distance travelled to the moon for a launch onHeight with payload: 124 feet tall (37.8 meters) and October 19:8 feet (2.4 meters) in diameter GRAIL-A = 2,243,336 miles (3,610,300 kilometers)Mass fully fueled: 622,662 pounds (282,435 GRAIL-B = 2,305,784 miles (3,710,800 kilometers)kilograms) Distance spacecraft travel in lunar orbit (from lunarFirst Stage: orbit insertion to end-of-mission):— Main engine (RS-27A) and nine (46-inch, or GRAIL-A = 13,193,550 miles (21,232,9611.2 meter) strap-on solid rocket motors kilometers)— LOX and RP-1 (kerosene), liftoff thrust of GRAIL-B = 12,800,869 miles (20,601,001207,000 pounds kilometers)— Each solid rocket motor produces136,400 pounds of thrustGRAIL Launch 6 Press Kit
  7. 7. Program The moon is actually moving away from Earth at aThe GRAIL mission totals about $496.2 million, rate of 1.5 inches (3.8 centimeters) per year.which includes spacecraft development and scienceinstruments, launch services, mission operations, The moon’s widest craters are 1,553 miles (2,500science processing and relay support. kilometers) in diameter.Moon Facts From Earth, we always see the same side of theThe actual Earth–moon distance ranges from about moon.223,700 to 251,700 miles (360,000 to 405,000kilometers), depending on the moon’s position in its If Earth did not have its moon, Earth would spin threeorbit. times as fast, making a day last only 8 hours instead of 24.The mean radius of the moon is 1,080 miles(1,737.4 kilometers); the diameter is 2,159.1 miles The age of the oldest moon rock collected by(3,474.8 kilometers). astronauts is 4.5 billion years old. The rocks collected during NASA’s Apollo program weigh in at 842Total mass of the moon is 81 quintillion tons (74 pounds (382 kilograms).sextillion kilograms). The surface temperature at theequator during the day is as high as 273 degrees The moon’s highest mountains are 5.6 miles high (9Fahrenheit (134 degrees Celsius) and at night is as kilometers).cold as minus 244 degrees Fahrenheit (minus 153degrees Celsius). The lunar day (or the time from sunrise to sunrise) on the moon is approximately 708 hours (29.5 days).Gravity at the surface of the moon is 1/6 that of Earth.The moon’s magnetic field is less than 0.01 that of The surface area of the moon is 23,559,000 squareEarth’s. miles (37,914,000 square kilometers). It has almost the same surface area as the continent of Africa.The orbital speed of the moon is 2,287 mph (3,680kilometers per hour). If you weighed 120 pounds, you would weigh only 20 pounds on the moon.At the closest distance, it would take 135 days todrive by car at 70 mph (113 kilometers per hour) to The moon has no significant atmosphere or clouds,the moon. and no known active volcanoes. There are two high tides and two low tides every day on every beach on Earth because of the moon’s gravitational pull.GRAIL Launch 7 Press Kit
  8. 8. Why GRAIL?The Gravity Recovery And Interior Laboratory and composition and to gain insights into its thermal(GRAIL) will unlock the mysteries of the moon hidden evolution — that is, the history of the moon’s heatingbelow its surface. It will do so by creating the most and cooling, which opens the door to understandingaccurate gravitational map of the moon to date, its origin and development. Accurate knowledgeimproving our knowledge of near-side gravity by 100 of the moon’s gravity will also be an invaluabletimes and of far-side gravity by 1,000 times. navigational aid for future lunar spacecraft. Finally, GRAIL will also help us understand the broaderThe high-resolution map of the moon’s gravitational evolutionary histories of the other rocky planets in thefield, especially when combined with a comparable- inner solar system: Mercury, Venus, Earth and Mars.resolution topographical field map, will enable Indeed, the moon is a linchpin for understanding howscientists to deduce the moon’s interior structure the terrestrial planets evolved.GRAIL Launch 8 Press Kit
  9. 9. Mission Overview Heliocentric View View from Ecliptic Z-axisThis figure shows a timeline of the GRAIL mission phases from launch through the various mission phases.Since the relative position of Earth and the moon change over this entire period, it is simplest to illustrate theevents relative to the sun, or heliocentric view. Once launched, GRAIL will enter a three-and-a-half-The twin GRAIL spacecraft (called GRAIL-A and month Trans-Lunar Cruise phase, which allows theGRAIL-B) will be launched side-by-side on a single two spacecraft to efficiently venture from Earth to theDelta II vehicle during a 42-day launch period that moon via the Sun-Earth Lagrange point 1. Lagrangeopens on September 8, 2011. point 1 is named for the Italian-French mathematician Joseph-Louis Lagrange. In 1764, he authored anThe GRAIL mission is divided into seven mission essay for the Paris Academy of Sciences, definingphases: Launch, Trans-Lunar Cruise, Lunar Orbit points between bodies in space where the gravityInsertion, Orbit Period Reduction,Transition to between them balances the centrifugal forceScience Formation, Science and Decommissioning. experienced at those points while orbiting with the bodies. This low-energy transfer was chosenGRAIL Launch 9 Press Kit
  10. 10. to reduce the size of the rocket required to place A series of maneuvers is then performed to reduceGRAIL on its correct trajectory, allow more time for the orbits to become nearly circular with a 34-milespacecraft check-out and increase the number of (55-kilometer) altitude.days available in the launch period. The 82-day Science Phase is divided into threeArrival at the moon occurs on a fixed date for both 27.3-day mapping cycles. During the Scienceorbiters and is independent of the launch date. The Phase, the moon will rotate three times underneathyear ends with the arrival of the GRAIL-A orbiter at the GRAIL orbit. The collection of gravity data overthe moon on Dec. 31, 2011, and the new year is one complete rotation (27.3 days) is referred to as aushered in with the GRAIL-B orbiter arriving at the Mapping Cycle.moon on Jan. 1, 2012. Both spacecraft approachthe moon under its south pole, where they execute Following the Science Phase, a five-daya 38-minute Lunar Orbit Insertion maneuver to put decommissioning period is planned, after whichthem in an elliptical orbit with an orbital period of just the spacecraft will impact the lunar surface inover 11.5 hours. approximately 40 days.GRAIL Launch 10 Press Kit
  11. 11. Mission Phases extends through the initial 24 hours after liftoff. During this phase, the orbiters will undergo launch, separation from the launch vehicle, initial Deep Space Network acquisition and solar array deployment. Launch Strategy To ensure a high probability of launching, GRAIL has developed a launch period strategy that has a 42-day launch period. On each day, there are two separate   instantaneous launch opportunities separated in time by approximately 39 minutes. On Sept. 8, the firstLaunch Phase launch opportunity is at 8:37 a.m. EDT (5:37 a.m.The Launch Phase begins when the orbiters transfer PDT). The second launch opportunity is 9:16 internal power at six minutes before liftoff and EDT (6:16 a.m. PDT). 10-ft dia. GRAIL Spacecraft Composite Payload Fairing Guidance Section Miniskirt Second Stage AJ10-118K Engine First Stage Interstage Fuel Tank (RP-1) Centerbody Oxidizer Tank (LO2) RS-27A Engine Solid Rocket MotorsGRAIL Launch 11 Press Kit
  12. 12. GRAIL’s Ride Into Space phase and is used to insert the vehicle into low EarthThe launch vehicle selected for the GRAIL mission orbit. After a coast phase, the second stage is usedis the United Launch Alliance Delta II 7920H-10C. once again to precisely provide the velocity changeThis is a two-stage (liquid propellant) launch needed to inject the spacecraft onto the desired low-vehicle with nine strap-on solid rocket motors and energy flight path toward the moon.a 9.8-foot-diameter (three-meter) payload fairing.The “H” designation identifies the vehicle as a Payload Interface and Fairing“Heavy” lift Delta II launch vehicle. This vehicle The two GRAIL orbiters are housed side-by-sideprovides more performance than the standard within a payload fairing that is 9.8 feet (3 meters) inDelta II vehicle by using larger strap-on solids diameter and 30 feet (8.88 meters) tall. The fairing isdeveloped for the Delta III launch vehicle. The used to protect the orbiters during the early portionlaunch vehicle is slightly more than 125 feet (38 of the boost phase when the aerodynamic forces aremeters) tall. great. The fairing will be jettisoned shortly after the ignition of Stage II, at about 281 seconds into flightStage I and an altitude of approximately 94.4 miles (152The first stage of the Delta II uses a Rocketdyne kilometers).RS-27A engine. This main engine is a single start,liquid bipropellant RS-27A engine. The Delta II Launch Profilepropellant load consists of RP-1 fuel (thermally The first stage or main engine and six of the ninestable kerosene) and liquid oxygen for the oxidizer. strap-on solid rocket motors are ignited at liftoff.The RP-1 fuel tank and the liquid oxygen tank The remaining three solids are ignited following theon the first stage are separated by a center burnout of the first six solids.body section that houses control electronics,ordnance sequencing equipment, a telemetry Following the main engine burn, the second stage willsystem and a rate gyro. The main engine will burn perform the first of its two burns, placingfor approximately 263 seconds, and will then be the orbiters into a 90-nautical mile (167 kilometer)jettisoned into the Atlantic Ocean. near-circular parking orbit. Following a coast period of just under an hour, the second stage will beGraphite-Epoxy Strap-on Solid Rocket Motors restarted, delivering the orbiters on their trajectory toFor the Delta II Heavy, nine strap-on graphite- the moon.epoxy motors are used to augment the main-engine thrust during the initial part of the ascent. Orbiter-Launch Vehicle SeparationThe strap-ons for the Delta II Heavy launch vehicle Beginning approximately three minutes after theare 46 inches (1,168 millimeters) in diameter and upper-stage has completed its final burn, the stageare fueled with approximately 37,500 pounds will perform an attitude maneuver that will reorient(17,000 kilograms) of hydroxyl-terminated the stage to the required separation attitude. Atpolybutadiene propellant. Six of the nine solid the completion of this maneuver, nine minutes androcket motors are ignited at the time of liftoff. The 30 seconds after the upper stage engine cutoff,remaining three, with extended nozzles, are ignited the second stage will send a signal that will causeshortly after the initial six strap-on motors burn out. the separation of GRAIL-A to occur. A little moreEach solid rocket motor will burn for approximately than seven minutes later, the upper stage will begin80 seconds. the maneuver to the desired attitude for GRAIL-B separation. This maneuver will reorient the secondSecond Stage stage 45 degrees away from the GRAIL-A separationThe second stage of the Delta II is powered by an attitude. Once the proper attitude is achieved for theAerojet AJ10-118K engine, burning a combination GRAIL-B spacecraft, a second signal will trigger theof Aerozine 50 (a 50/50 mix of hydrazine and separation of GRAIL-B at 8 minutes and 15 secondsunsymmetric dimethyl-hydrazine) and nitrogen after the GRAIL-A separation.tetroxide as the oxidizer. The second stage is arestartable stage. The first burn of the second Separation of a GRAIL spacecraft from the launchstage occurs during the final portion of the boost vehicle is detected using three separation breakwiresGRAIL Launch 12 Press Kit
  13. 13. Separation and initial acquisition graphic for a Sept. 8 launch date.on the spacecraft. Once a majority of these breakwires Trans-Lunar Cruise Phaseindicate that separation has occurred, the spacecraft The Trans-Lunar Cruise Phase is the period of timewill autonomously begin to execute commands when both orbiters will be en route to the moon viathat were loaded prior to liftoff. Confirmation of the a low-energy trajectory. This phase will include aseparation events will be provided by the launch series of checkouts and calibrations to characterizevehicle telemetry. In addition, visual confirmation of the performance of the spacecraft and payloadeach orbiter’s separation is expected via video from subsystems, as well as navigation activities requireda RocketCam mounted on the second stage of the for determining and correcting the vehicle’s flightlaunch vehicle. path, and activities to prepare for lunar orbit insertion.The deployment of the solar arrays occurs in sunlight, During the Trans-Lunar Cruise Phase, up to fiveshortly after exit from solar eclipse, and is visible trajectory correction maneuvers will be performed.from NASA’s Deep Space Network tracking stations The second and third maneuver will separate theat Goldstone, Calif. This will allow the telemetry GRAIL-A and GRAIL-B arrival times at the moon byassociated with the deployment to be downlinked to approximately one day.Earth in real time. Lunar Orbit Insertion PhaseBoth solar arrays will be commanded to deploy at The primary focus for this phase is the critical lunarnearly the same time. It will take, at most,127 seconds orbit insertion maneuver. This phase begins threefor the arrays to reach their fully deployed positions. days prior to GRAIL-A arrival at the moon, and endsGRAIL Launch 13 Press Kit
  14. 14. View of GRAIL’s trajectory looking down at Earth-moon systemThe figure shows GRAIL-A and GRAIL-B trajectories for a launch at the open and close of the launch period.The low-energy trajectories leave Earth following a path towards the sun, passing near the interior Sun-EarthLagrange Point 1 (Earth Libration Point 1) before heading back towards the Earth-moon day past the Lunar Orbit Insertion burn for maneuvers, grouped into two different clusters forGRAIL-B. each orbiter, performed to reduce the orbit period from 11.5 hours down to just under two hours.Both orbiters approach the moon from the south,flying nearly directly over the lunar south pole. The Transition to Science Formation Phaselunar orbit insertion burn for each spacecraft lasts From launch through the end of the previousapproximately 38 minutes and changes the orbiter phase, the two orbiters will be operated essentiallyvelocity by about 427 mph (191 meters per second). independently. Activities on GRAIL-A and GRAIL-BSeparated by about 25 hours, the lunar orbit insertion are separated in time to reduce operations conflictsmaneuvers will place each orbiter into a near-polar, and competition for ground resources. No attemptelliptical orbit with a period of 11.5 hours. These is made to fly the two orbiters in a coordinatedmaneuvers will be simultaneously visible from Deep manner. That all changes in the Transition to ScienceSpace Network tracking stations in Madrid, Spain and Formation Phase, when for the first time, the positionGoldstone, Calif. of one orbiter relative to the other becomes relevant.Orbit Period Reduction Phase The configuration of the two GRAIL orbiters is slightlyThe Orbit Period Reduction Phase starts one day different, making the order in which they orbit theafter the lunar orbit insertion maneuver for GRAIL-B moon extremely important. At the beginning of theand continues for five weeks. It includes a series of Transition to Science Formation Phase, the orbitGRAIL Launch 14 Press Kit
  15. 15. End of LOI Burn Moon North Pole Start of LOI BurnThe incoming trajectory and Lunar Orbit Insertion (LOI) burn of GRAIL-A.Blue line depicts the “burn arch” forthe spacecraft. Yellow line marks the moon’s terminator at time of insertion.period for GRAIL-B is targeted to be approximately At the start of the Science Phase, the GRAIL spacecraftthree minutes larger than the period of GRAIL-A. This will be in a near-polar, near-circular orbit with an altitudedifference in period means that the GRAIL-A orbiter, of about 34 miles (55 kilometers). The initial conditionsflying below the GRAIL-B orbiter, will lap the GRAIL-B have been designed so that the natural perturbationsorbiter once every three days. This creates a situation of the lunar gravity field allow the orbit to evolve withoutwhere subsequent maneuvers can be timed so requiring any orbit maintenance maneuvers.that the distance between the two orbiters can bemanaged and reduced in a controlled manner. The science orbit is designed to satisfy the basic science requirements of the GRAIL mission, whichA series of rendezvous-like maneuvers will be are for a low-altitude, near-circular, near-polar orbitperformed in this phase to achieve the desired initial that does not require any maneuvers to maintain theseparation distance and ensure that GRAIL-B is orbit. The primary design parameter from a scienceahead of the GRAIL-A in the formation. perspective is the orbit altitude, since sensitivity to the lunar gravity field is driven by orbit altitude (i.e.Science Phase the lower the altitude, the more sensitive the scienceThe Science Phase activities consist of the collection measurements). Limits on the minimum orbit altitudeof gravity science data and the execution of are driven primarily by orbit lifetime considerations.Education and Public Outreach activities using theMoonKAM system.GRAIL Launch 15 Press Kit
  16. 16.  The two GRAIL spacecraft.During the 82-day Science Phase, the moon will Decommissioning Phaserotate three times underneath the GRAIL orbit. The The final phase of the GRAIL mission is thecollection of gravity data over one complete rotation Decommissioning Phase. During this seven-day(27.3 days) is referred to as a Mapping Cycle. phase, the orbiters will perform a final Ka-band calibration and will continue to acquire science data,During Mapping Cycle 1, the mean separation as power and thermal resources allow. The missiondistance between the two spacecraft is designed to phase ends at the time of a partial lunar eclipse onincrease from approximately 62 to 140 miles (100 June 4, 2012.kilometers to 225 kilometers). A very small OrbitTrim Maneuver executed near the end of Mapping The design of the GRAIL science orbit is such that,Cycle 1 will then be used to change the separation at the end of the Science Phase, the orbits of thedrift rate. Following this orbital trim maneuver, the two spacecraft carry them to within approximatelymean separation distance will decrease from 140 9.3 to 12.4 miles (15 to 20 kilometers) above themiles (225 kilometers) to approximately 40 miles (65 lunar surface at their lowest point. If no maneuverskilometers) at the end of Mapping Cycle 3 (the end are executed after this point, both orbiters willof the Science Phase). The change in separation impact the lunar surface during, or shortly after, thisdistance is required to meet the GRAIL science mission phase. The GRAIL mission is expected toobjectives. The data collected when the orbiters are end within a few days of the partial lunar eclipse incloser together helps to determine the local gravity June 2012. There are no plans to target the impactfield, while data collected when the separation points on the lunar surface.distances are larger will be more useful in satisfyingthe science objectives related to detection andcharacterization of the lunar core.GRAIL Launch 16 Press Kit
  17. 17. SpacecraftTwo orbiters are part of the GRAIL mission; one isdesignated GRAIL-A and the other GRAIL-B.  Technicians prepare to hoist one of the two GRAIL spacecraft upon completion of a thermal vacuum test at theLockheed Martin Space Systems facility in Denver. Image Credit: NASA/JPL-Caltech/LMSSThe two Lockheed-Martin built spacecraft are Structurenearly identical, but there are a few important GRAIL comprises twin spacecraft built on thedifferences between them due to the need to point Lockheed Martin Experimental Small Satellite (XSS-the spacecraft at one another during the Science 11) bus, with a science payload derived from thePhase of the mission. These include the angles at GRACE terrestrial gravity mission. The GRAIL bus iswhich their star trackers are pointing, the Lunar a rectangular composite structure with a dry mass ofGravity Ranging System antenna cant angle, and the about 443 pounds (201 kilograms), and fully fueledMoonKAM mounting. In addition, during the Science mass of about 677 pounds (307 kilograms).Phase, the orientation of the orbiters is different.They will fly facing each other — one forward and the Attitude Control Subsystemother backward — so they can point their Ka-band The Attitude Control subsystem is used to provideantennas at each other. three-axis stabilized control throughout the mission.GRAIL Launch 17 Press Kit
  18. 18. This subsystem consists of a sun sensor, a star 26 strings per panel. The solar arrays are deployedtracker, reaction wheels, and an inertial measurement shortly after separation from the launch vehicle andunit. remain fixed throughout the mission.Propulsion System The lithium-ion battery has a capacity of 30 amp-The propulsion subsystem provides propulsive hours, and is used to provide energy to the orbiterimpulse for all large maneuvers including trajectory during periods when the solar arrays are not able tocorrection maneuvers, lunar orbit insertion and generate enough power for the orbiter systems.circularization maneuvers. The propulsion systemconsists of a propellant storage tank, a high-pressure Telecommunicationshelium recharge tank, a feed system for propellant The telecom subsystem is responsible for sendingloading and distribution, a hydrazine catalytic thruster telemetry and radiometric data from the orbiter andfor change-in-velocity impulse delivery, a warm gas receiving commands from the ground during theattitude control system, and eight warm gas attitude mission. The telecom subsystem for GRAIL consistscontrol system thruster valves. of an S-band transponder, two low gain antennas, and a single-pole, double-throw coaxial switch usedThe main engine is an MR-106L 22 Newton liquid to alternate between the two antennas. The low gainhydrazine thruster. The main engine provides the antennas are the mission controllers’ primary meansmajority of the thrust for spacecraft trajectory of communicating with the spacecraft and enablecorrection maneuvers. The warm gas attitude control each spacecraft to communicate with each other.system thrusters will be used for the small maneuversplanned for the Science Phase of the mission. Science Instruments The payload on each orbiter consists of a LunarThe warm gas attitude control system utilizes eight Gravity Ranging System and an education and public0.9 Newton thrusters. The attitude control thrusters outreach MoonKAM System.are canted to provide coupled thrust during mainengine maneuvers. The warm gas thruster locations Lunar Gravity Ranging Systemhave been designed to minimize plume impingement The primary payload of the GRAIL spacecraft ison the main body and solar arrays. the Lunar Gravity Ranging System. The system is responsible for sending and receiving the signalsCommand & Data Handling needed to accurately and precisely measure theThe Command and Data Handling subsystem is changes in range between the two orbiters as theyused for telemetry and command processing for the fly over lunar terrain of varying density. To accomplishorbiter. The single-string command and data handling this, the Lunar Gravity Ranging System consists ofsubsystem also features an enhanced RAD-750 an ultra-stable oscillator, microwave assembly, a timespacecraft computer with 128 megabytes of Static transfer assembly, and the gravity recovery processorDynamic random access memory. In addition, there assembly.are 512 megabytes of storage within the Memory andPayload Interface Card for recorded data. The ultra-stable oscillator provides a steady reference signal that is used by all the instrument subsystems.Power The microwave assembly converts the oscillator’sThe electrical power subsystem is responsible for reference signal to the Ka-band frequency, whichgenerating and storing energy for each orbiter and its is transmitted to the other orbiter. The function ofsystems. This power subsystem includes two solar the time transfer assembly is to provide a two-wayarrays and a lithium-ion battery. time transfer link between the spacecraft to both synchronize and measure the clock offset betweenThere are two solar arrays, which generate the energy the clocks aboard the two operate the orbiter systems. Each solar array hasan area of 6.2 square feet (1.88 square meters) and The time transfer assembly generates an S-bandis capable of producing 700 watts of power at the signal from the ultra-stable oscillator referenceend of the mission. There are 20 cells per string and frequency and sends a GPS-like ranging code toGRAIL Launch 18 Press Kit
  19. 19. the other spacecraft. The gravity recovery processor GRAIL Bloodlineassembly combines all the inputs received to produce GRAIL will build on the heritage of a predecessorthe radiometric data that is downlinked to the ground. mission called the Challenging Minisatellite Payload, or “Champ.” Built by Germany’s Earth ResearchOutreach Instrument — MoonKAM Center (GeoForschungsZentrum) and launched inMoonKAM is a digital video imaging system that is July 2000, Champ’s instruments and its orbit haveused as part of the education and public allowed it to generate simultaneous, highly preciseoutreach activities for GRAIL. Each MoonKAM measurements of Earth’s gravity and magnetic field.system (one per spacecraft) consists of a digital videocontroller and four camera heads — one pointed While Champ has significantly advanced the field ofslightly forward of the spacecraft, two pointed directly geodesy, scientists desired an even more advancedbelow it, and one pointed slightly backward. The mission based upon dual satellites flying in video controller serves as the main interface The unique design of NASA’s GRACE Earth-observingto the spacecraft and provides storage for images mission led to a hundred-fold improvement in existingacquired by the camera heads. This system can be gravity maps and allow much improved resolutionused to take images or video of the lunar surface with of the broad- to finer-scale features of Earth’sa frame rate up to 30 frames per second. gravitational field over both land and sea, while also showing how much Earth’s gravitational field variesThe MoonKAM system is provided by Ecliptic with time.Enterprises Corporation, Pasadena, Calif., and isoperated by undergraduate students at the University The design of the GRAIL spacecraft is based on theof California at San Diego under supervision of faculty Experimental Small Satellite-11 (XSS-11) technologyand in coordination with Sally Ride Science. Middle demonstration mission for the United States Airschool students from around the country will have Force, the Mars Reconnaissance Orbiter (MRO)an opportunity to become involved with MoonKAM and the Gravity Recovery and Climate Experimentimaging. During the Science Phase, operations will be (GRACE) missions for NASA.conducted in a non-time-critical, ground-interactivemode.GRAIL Launch 19 Press Kit
  20. 20. Why Study Gravity?Gravity is Newton’s apple and the stuff of Einstein’s are many miles high, lava flows several hundredtheory of relativity, but it is also the law that we all miles long and enormous lava tubes and craters oflearn to obey from our first breath of life. Gravity is the every size. Below the surface, things are even moremutual attraction that pulls two masses together and complex and variable. In fact, the moon has thekeeps us firmly planted on Earth. lumpiest gravitational field known in our solar system. Studying its gravity allows us to betterSir Isaac Newton first revealed the law of gravity understand the forces that have shaped our naturalmore than 300 years ago. During the 20th century, satellite.geophysicists developed techniques to locate mineraldeposits and underground formations using spatial For example, the material that makes up the moon’schanges in Earth’s gravity field. Their work laid the highlands has a different density than that makingmodern foundation for the science of geodesy. Today, up its “seas,” or “maria.” Since the highland materialscientists use measurements from several dozen is less dense than maria material, the gravity in thesatellites to develop models of Earth’s “geoid” — an maria region is usually subtly stronger. Such unevenimaginary surface upon which the pull of gravity is distribution of mass on the moon’s surface and inequal everywhere. its interior manifests itself as “lumps” in the planet’s gravity field.Planetary scientists have taken the study of gravityfields to new heights — and other worlds. The GRAIL Previous space missions have mapped themission will forward this scientific endeavor, creating gravity fields of asteroids, Venus, Mars, Jupiter,the most accurate gravitational map of the moon to Saturn and Earth. Even Earth’s moon, the objectdate. of GRAIL’s attention, has had its gravity field measured on numerous occasions with varyingIf the moon were a smooth sphere of uniform density, degrees of success. But the accuracy of the GRAILthere would be no need for a mission data will surpass by orders of magnitude thatlike GRAIL — it would measure no changes in the previously obtained, which will allow a new level ofgravity field. However, the moon isn’t smooth and understanding about Earth’s nearest neighbor.homogeneous — its surface includes mountains thatGRAIL Launch 20 Press Kit
  21. 21. Science OverviewGRAIL Science Overview Why thermal evolution? A planetary body suchThe primary science objectives are to determine the as the moon, Earth, and the other terrestrialstructure of the lunar interior, from crust to core, and planets,forms by accretion of primordial dust andto advance understanding of the thermal evolution rock. Eventually, this protoplanet is heated to theof the moon. The secondary science objective is to melting point by meteoroids smashing into it andextend knowledge gained from the moon to other by breakdown of radioactive elements within it.terrestrial planets. These objectives will be achieved Then, over the eons, it cools off by radiating its heatby obtaining a global, high-accuracy, high-resolution into space. While it’s still molten, heavy materialslunar map during a 90-day Science Phase. sink down toward the core and lighter materials float on top, ultimately forming a crust. The storyThe GRAIL mission will create the most accurate of how a particular planetary body processes itsgravitational map of the moon to date, improving heat and how, when and where heat is replenishedour knowledge of gravity on the side facing Earth by by meteorite impacts and radioactive elements100 times and of gravity on the side not facing Earth break down is the story of how its structure cameby 1,000 times. The high-resolution gravitational to be. So understanding the moon’s thermalfield, especially when combined with a comparable- evolution is essential to understanding its origin andresolution topographical field, will enable scientists deduce the moon’s interior structure andcomposition, and to gain insights into its thermal The mission’s secondary objective is to extend theevolution — that is, the history of the moon’s heating knowledge it will gain about the moon to informand cooling, which opens the door to understanding our understanding of the development of the otherits origin and development. Accurate knowledge planetary bodies in the inner solar system: Mercury,of the moon’s gravity will also be an invaluable Venus, Earth and Mars. As the most accessiblenavigational aid for future lunar spacecraft. Ultimately, planetary body besides Earth, and as one thatthe information contributed by the GRAIL mission will is thought to have changed little since its initialincrease our knowledge of how Earth and its rocky development (unlike Earth, Mars, and Venus), theneighbors in the inner solar system developed into the moon offers a unique look into the distant past ofdiverse worlds we see today. planetary evolution.Science Objectives The GRAIL mission’s six science investigations:The moon is the most accessible and best studied 1. Map the structure of the lithosphere.of the rocky (aka “terrestrial”) bodies beyond Earth.Unlike Earth, however, the moon’s surface geology The lithosphere is the portion of the crust and upperpreserves the record of nearly the entirety of 4.5 mantle with significant strength over a geologicalbillion years of solar system history. In fact, orbital time scale. Since the strength of rock is highlyobservations combined with samples of surface dependent on temperature, the thickness of therocks returned to Earth indicate that no other body lithosphere is directly related to thermal evolution.preserves the record of geological history as clearly GRAIL will provide evidence of how rigid theas the moon. lithosphere was — and therefore what the thermal conditions were — at various locations whenThe need to understand the lunar internal structure features were order to reconstruct planetary evolution motivatesGRAIL’s primary science objectives, which are to 2. Understand the moon’s asymmetric thermaldetermine the structure of the lunar interior from evolution.crust to core and to further the understanding of thethermal evolution of the moon. The thickness of the crust suggests the extent to which the surface was melted in its early history. TheGRAIL Launch 21 Press Kit
  22. 22. moon’s crust has a variable structure, thinner on the impact craters on Earth), magmatism (the movementnear side than on the far side, except for the south of molten rock inside the moon), and isostaticpole Aitken basin region, and thinned beneath the compensation (a process by which a planetary bodymajor impact basins. Scientists would like to know evens out the distribution of its mass — for example,why. by distorting the boundary between the crust and mantle beneath a large impact basin).3. Determine the subsurface structure of impactbasins and the origin of mascons. 5. Constrain deep interior structure from tides.A surprising discovery was made in the 1960s, Earth’s gravity creates tides in the solid moon, just aswhen it was found that the moon’s gravity was the moon creates tides in Earth’s ocean. Of course,unexpectedly strong over certain impact basins, and the moon’s rocky surface doesn’t bulge as much asthat this is what had been pulling lunar spacecraft water would — it only deforms about 3.5 inches (9off course. It was deduced that these impact basins centimeters) in response to Earth’s gravity from onehave large mass concentrations (or “mascons” for part of the lunar orbit to another. But what’s significantshort) underneath them. GRAIL will provide more to GRAIL is that the moon responds to Earth’s gravityinformation about the nature of these mascons. all the way down to the core, and different internal structures would produce differences in the way4. Ascertain the temporal evolution of crustal the moon’s gravitational field deforms. By analyzingbrecciation and magmatism. how the field deforms at various parts of the moon’s orbit around Earth, scientists will be able to deduceAnalyses of a set of lunar craters indicate that those information about the core and other deep features.that formed less than 3.2 billion years ago showless gravity than the surrounding plain, while those 6. Place limits on the size of a possible solid innerformed earlier show about the same gravity as the core.surrounding plain. GRAIL will help to explain thereasons, including the roles played by brecciation GRAIL scientists will search for evidence of a solid(the formation of new rocks by cementing together core within the liquid core the moon is believed tofragments of older rocks, often found beneath have, and the data they receive will place limits on how big that solid core could be.GRAIL Launch 22 Press Kit
  23. 23. Science TeamGRAIL Science Team Co-InvestigatorsMaria Zuber, Alexander S. Konopliv,principal investigator, NASA’s Jet Propulsion Laboratory,Massachusetts Institute of Technology, Pasadena, CalifCambridge Frank G. Lemoine, Goddard Space Flight Center,David E. Smith, Greenbelt, Md.deputy principal investigator,Goddard Space Flight Center, Jay Melosh,Greenbelt, Md. University of Arizona, TucsonMichael Watkins, Gregory A. Neumann,project scientist, Goddard Space Flight Center,Jet Propulsion Laboratory, Greenbelt, Md.Pasadena Roger J. Phillips,Sami Asmar, Southwest Research Institute,deputy project scientist, San AntonioJet Propulsion Laboratory, Pasadena Sean C. Solomon, Carnegie Institution for Science, Washington, DC Mark Wieczorek, University of Paris James G. Williams, Jet Propulsion Laboratory, Pasadena, Calif.GRAIL Launch 23 Press Kit
  24. 24. Missions to the MoonHistorical Exploration of the Moon 1968 NASA’s Apollo 8 made the first manned flight to the1609 moon, circling it 10 times before returning to Earth.Hans Lippershey invented the telescope. 19691610 Apollo 11 mission made the first landing on the moonItalian astronomer Galileo Galilei made the first and returned samples.telescopic observation of the moon. 19691610 (Nov.) Apollo 12 made first precision landing on theThomas Harriot and Galileo Galilei drew the first the moon.telescopic representation of the moon. 19721645 Apollo 17 made the last manned landing of the ApolloMichael Florent van Langren made the first map of Program.the moon. 19761647 Soviet Luna 24 returned the last sample to beJohannes Hevelius published the first treatise returned from the moon (to date).devoted to the moon. 19901651 NASA’s Galileo spacecraft obtained multispectralGiovanni Battista Riccioli named craters after images of the western limb and part of the far side ofphilosophers and astronomers. the moon.1753 1994Roger Joseph Boscovich proved the moon has no NASA’s Clementine mission conducted multispectralatmosphere. mapping of the moon.1824 1998Franz von Gruithuisen thought craters were NASA’s Lunar Prospector launched.formed by meteor strikes. 20071920 Japanese SELENE (Kaguya) launched.Robert Goddard suggested sending rockets to themoon. 2007 Chinese Chang’e 1 launched.1959Soviet spacecraft Luna 2 reached the moon, 2008impacting near the crater Autolycus. Indian Chandrayaan 1 launched.1961 2009President John F. Kennedy proposed a manned NASA’s Lunar Reconnaissance Orbiter launchedlunar program.1964 Future NASA Lunar MissionsNASA’s Ranger 7 produced the first close-up TV 2012 LADEE (orbiter) — Lunar Atmosphere and Dustpictures of the lunar surface. Environment Explorer is a NASA mission that will orbit1966 the moon. Its main objective is to characterize theSoviet spacecraft Luna 9 made the first soft atmosphere and lunar dust environment. In additionlanding on the moon. to the science objectives, the mission will be testing1967 a new spacecraft architecture called the “ModularNASA’s Lunar Orbiter missions completed Common Bus,” which is being developed by NASAphotographic mapping of the moon. as a flexible, low-cost, rapid-turnaround spacecraft for both orbiting and landing on the moon and other deep space targets.GRAIL Launch 24 Press Kit
  25. 25. NASA’s Discovery ProgramGRAIL will be the eleventh Discovery Program mission • Launched Feb. 7, 1999, Stardust captured andto enter space. returned to Earth interstellar dust particles and comet dust using an unusual substance calledAs a complement to NASA’s larger “flagship” aerogel. On Jan. 2, 2004, it flew within 149 milesplanetary science explorations, the Discovery (240 kilometers) of the nucleus of Comet Wild 2,Program goal is to achieve outstanding results collecting samples of comet dust and snappingby launching many smaller missions using fewer detailed pictures of the comet’s surface. Onresources and shorter development times. The main Jan. 15, 2006, Stardust’s sample return capsuleobjective is to enhance our understanding of the returned to Earth, providing scientists worldwidesolar system by exploring the planets, their moons, with the opportunity to analyze the earliestand small bodies such as comets and asteroids. The materials that created the solar system. NASAprogram also seeks to improve performance through extended Stardust’s mission to fly by cometthe use of new technology and broaden university Tempel 1, which occurred on Feb. 14, 2011.and industry participation in NASA missions. That mission was referred to as Stardust-NExT. The spacecraft obtained images of the scar onFurther information on NASA’s Discovery program can Tempel 1’s surface produced by NASA’s Deepbe found at: Impact in 2005 and revealed changes to the comet’s surface since a recent close approachPrevious NASA Discovery program missions: to the sun. It also imaged new terrain not seen during the Deep Impact mission and took new• Near Earth Asteroid Rendezvous was launched dust measurements. Feb. 17, 1996. It became the first spacecraft to orbit an asteroid when it reached Eros in February • Launched Aug. 8, 2001, Genesis collected atoms 2000. After a year in orbit, it achieved the first of solar wind beyond the orbit of Earth’s moon to landing on an asteroid in February 2001, after accurately measure the composition of our sun returning more than 160,000 detailed images. and improve our understanding of solar system “Shoemaker” was later added to the spacecraft’s formation. Its sample return capsule made a name in honor of the late planetary scientist hard landing at the time of Earth return on Sept. Eugene Shoemaker. 8,2004. The mission’s samples of solar wind were recovered and are currently being analyzed• Mars Pathfinder was launched Dec. 4, 1996, by scientists at laboratories around the world. and landed on Mars on July 4, 1997. It was the first free-ranging rover to explore the Martian • The Comet Nucleus Tour launched from Cape surface, conducting science and technology Canaveral on July 3, 2002. Six weeks later, experiments. Pathfinder’s lander operated nearly contact with the spacecraft was lost after a three times longer than its design lifetime of 30 planned maneuver that was intended to propel days, and the Sojourner rover operated 12 times it out of Earth orbit and into a comet-chasing its design lifetime of seven days. After sending solar orbit. The probable proximate cause was back thousands of images and measurements, structural failure of the spacecraft due to plume the mission ended Sept. 27, 1997. heating during the embedded solid-rocket motor burn.• Lunar Prospector was launched Jan. 6, 1998. It orbited Earth’s moon for 18 months, looking for • The Mercury Surface, Space Environment, water and other natural resources and returning Geochemistry and Ranging (MESSENGER) extensive mapping data to provide insights into spacecraft was launched Aug. 3, 2004. It lunar origin and evolution. At the mission’s end entered orbit around the planet closest to the on July 31, 1999, the spacecraft was intentionally sun in March 2011. The spacecraft is mapping crashed into a crater near the moon’s south pole nearly the entire planet in color and measuring in an attempt to detect the presence of water. the composition of the surface, atmosphere and magnetosphere.GRAIL Launch 25 Press Kit
  26. 26. • Launched Jan. 12, 2005, Deep Impact was the at Ceres in February 2015. Studying Vesta and first experiment to send a large projectile into Ceres, the two most massive objects in the the path of a comet to reveal the hidden interior asteroid belt, allows scientists to do historical for extensive study. On July 4, 2005, traveling research in space, opening a window into at 23,000 mph (39,000 kilometers per hour) a the earliest chapter in the history of our solar larger flyby spacecraft released a smaller impactor system. At each target, Dawn will acquire color spacecraft into the path of comet Tempel 1 as photographs, compile topographic maps, map both recorded observations. The Spitzer, Hubble the elemental composition, map the mineralogical and Chandra space telescopes also observed composition, measure the gravity field and search from space, while an unprecedented global for moons. The data gathered by Dawn will network of professional and amateur astronomers enable scientists to understand the conditions captured views of the impact, which took place under which these objects formed, determine 83 million miles (138 million kilometers) from the nature of the building blocks from which Earth. NASA extended the Deep Impact mission the terrestrial planets formed and contrast the as EPOXI, a combination of the names for the formation and evolution of Vesta and Ceres. mission’s two components: the Extrasolar Planet Observations and Characterization (EPOCh),and • Launched on March 6, 2009, Kepler is in the the flyby of comet Hartley 2, called the Deep middle of its prime mission to monitor more than Impact Extended Investigation (DIXI). The EPOXI 100,000 stars similar to our sun. The mission mission successfully flew by comet Hartley 2 on was designed to find Earth-sized planets in orbit Nov. 4, 2011, obtaining the first images clear around stars outside our solar system. With enough for scientists to link jets of dust and gas its vast field of view, Kepler detects transits of with specific surface features. thousands of planets. So far, it has identified more than 1,200 planet candidates, some of which• Launched on Sept. 27, 2007, NASA’s Dawn lie in the “habitable” zones of their stars, where spacecraft will be the first to orbit two bodies in temperatures permit water to be in a liquid state. the main asteroid belt, Vesta and Ceres. Dawn Kepler has also discovered the smallest known arrived at Vesta on Friday, July 15. The spacecraft rocky planet, called Kepler-10b, measuring at 1.4 will spend a year orbiting the giant asteroid, times the size of Earth. before traveling to its second destination, arrivingGRAIL Launch 26 Press Kit
  27. 27. Program/Policy ManagementGRAIL’s principal investigator is Maria Zuber of the William Knopf is GRAIL program executive, andMassachusetts Institute of technology, Cambridge. Robert Fogel is GRAIL program scientist.Michael Watkins and Sami Asmar, of NASA’s Dennon Clardy of NASA’s Marshall Space FlightJet Propulsion Laboratory, Pasadena, Calif., are Center is the Discovery program manager.GRAIL’s project scientist and deputy-project scientist,respectively. At JPL, David Lehman is GRAIL project manager. Tom Hoffman is deputy project manager. JPL isThe GRAIL project is managed by the Jet Propulsion a division of the California Institute of Technology,Laboratory, Pasadena, Calif., for NASA’s Science Pasadena, Calif.Mission Directorate, Washington. The GRAIL missionis part of the Discovery Program managed at Lockheed Martin Space Systems Company,NASA’s Marshall Space Flight Center in Huntsville, Denver built the GRAIL spacecraft and will handleAla. Launch management for the mission is the its day-to-day operations. John Henkis is theresponsibility of NASA’s Launch Services Program at company’s GRAIL program manager and leads thethe Kennedy Space Center in Florida. flight team.At NASA Headquarters, Ed Weiler is associate The United Launch Alliance is responsible foradministrator for the Science Mission Directorate. the Delta II rocket which will carry GRAIL into space.James Green is director of the Planetary Division. More information about NASA’s GRAIL mission can be found online at http://www. and Launch 27 Press Kit