API VERSION: 1.2 API SOURCE: NASA/JPL Horizons API ****************************************************************************** Revised: 2024-Dec-05 Chandrayaan-2 Orbiter Spacecraft / (Moon) -152 NOTE: This is the ORBITER trajectory. The lander ("Vikram") separated from the orbiter on 2019-Sep-02 07:45 UTC. The LANDER trajectory ID is -153. PURPOSE The primary objective of ISRO's Chandrayaan-2 is to demonstrate the ability to soft-land on the lunar surface and operate a robotic rover on the surface. Scientific goals include studies of lunar topography, mineralogy, elemental abundance, the lunar exosphere, and signatures of hydroxyl and water ice. BACKGROUND Chandrayaan-2 launched 2019-July-22 @ 09:13 UTC from Satish Dhawan Space Centre on Sriharikota Island, India. Launch vehicle was a GSLV-MK3. Mission consists of an orbiter, a lander ("Vikram") and a rover ("Pragyan") After launch into Earth parking orbit (170 x 40400 km altitude), a series of maneuvers will progressively raise the apogee of the spacecraft until a subsequent trans-lunar injection burn. Injection to lunar transfer orbit will occur 2019-Aug-14. It was inserted into an initial elliptic lunar orbit on Aug 20 (114 x 18072 km) and the first of a sequence of maneuvers executed, lowering apoapsis to 4412 km. The orbiter was eventually placed in a 119 x 127 km nearly circular polar orbit after a series of engine burns. The lander subsequently separated on 2019-Sep-02 07:45 UTC and will touch down at predetermined site close to the lunar south pole. Touchdown is to occur 2019-Sep-07 on a high plain between two craters, Manzinus C and Simpelius N, about 70 degrees south of the equator. [NOTE: landing failed, lander & rover were lost] The orbiter mission covers 1 year, in a 100-km circular polar orbit. The six-wheeled Pragyan rover, whose name means "wisdom" in Sanskrit, will be deployed from a ramp after landing. It is solar-powered and capable of traveling up to 500 meters on the lunar surface at a speed of 1 cm/s. The lander/rover missions are planned for 14-15 days (1 lunar daylight interval). SPACECRAFT DETAILS Launch mass : 3850 kg Lunar orbital mass: 2379 kg (solar arrays ~1000 W Lunar lander mass: 1471 kg (solar arrays ~ 650 W) Rover mass : 27 kg (solar arrays ~ 50 W) TRAJECTORY: This is a merge of post-launch trajectory solutions fit to tracking data through 2024-Dec-04, with a prediction thereafter. Trajectory name Start (TDB) Stop (TDB) ----------------------------------------- ----------------- ----------------- ch2o_spk_190722-[200901_od*]_v*_dsn.V0.* 2019-Jul-22 09:31 2020-Jun-01 09:01 ISRO_CH2*-OD* 2020-Jun-01 09:01 2025-Jan-22 08:25 ******************************************************************************* ******************************************************************************* Ephemeris / API_USER Thu Dec 12 01:44:11 2024 Pasadena, USA / Horizons ******************************************************************************* Target body name: Chandrayaan-2 (ORBITER) (spacecraft) (-152) {source: chandrayaan-2_orbiter_me} Center body name: Earth (399) {source: chandrayaan-2_orbiter_me} Center-site name: VdS Remote Observatory, Hakos ******************************************************************************* Start time : A.D. 2024-Nov-30 00:00:00.0000 UT Stop time : A.D. 2024-Dec-01 00:00:00.0000 UT Step-size : 10 minutes ******************************************************************************* Target pole/equ : undefined Target radii : undefined Center geodetic : 16.3613, -23.2365766, 1.8515 {E-lon(deg),Lat(deg),Alt(km)} Center cylindric: 16.3613,5865.52307,-2501.54567 {E-lon(deg),Dxy(km),Dz(km)} Center pole/equ : ITRF93 {East-longitude positive} Center radii : 6378.137, 6378.137, 6356.752 km {Equator_a, b, pole_c} Target primary : 301 Vis. interferer : MOON (R_eq= 1737.400) km {source: chandrayaan-2_orbite Rel. light bend : Sun {source: chandrayaan-2_orbite Rel. lght bnd GM: 1.3271E+11 km^3/s^2 Atmos refraction: NO (AIRLESS) RA format : HMS Time format : CAL Calendar mode : Mixed Julian/Gregorian RTS-only print : NO EOP file : eop.241211.p250309 EOP coverage : DATA-BASED 1962-JAN-20 TO 2024-DEC-11. PREDICTS-> 2025-MAR-08 Units conversion: 1 au= 149597870.700 km, c= 299792.458 km/s, 1 day= 86400.0 s Table cut-offs 1: Elevation ( 0.0deg=YES),Airmass (>38.000=NO), Daylight (YES) Table cut-offs 2: Solar elongation ( 12.0,180.0=YES),Local Hour Angle( 0.0=NO ) Table cut-offs 3: RA/DEC angular rate ( 0.0=NO ) *************************************************************************************************************************************************************************************************************************************************** Date__(UT)__HR:MN R.A._____(ICRF)_____DEC Azi____(a-app)___Elev APmag S-brt r rdot delta deldot S-O-T /r S-T-O T-O-M/MN_Illu% RA_3sigma DEC_3sigma Sky_motion Sky_mot_PA RelVel-ANG *************************************************************************************************************************************************************************************************************************************************** $$SOE >..... Elevation Cut-off Requested .....< 2024-Nov-30 03:10 Nm 15 31 39.84 -22 27 50.1 114.528666 0.287707 n.a. n.a. 0.983644655084 -0.1789402 0.00267960668203 -0.7280717 12.4249 /L 167.5413 -.1730/ 1.2090 n.a. n.a. 50.925582 45.640853 -23.81840 2024-Nov-30 03:20 Nm 15 31 59.62 -22 22 28.8 113.511101 2.285350 n.a. n.a. 0.983645387801 0.5135178 0.00267545605164 -1.3117693 12.3539 /L 167.6125 -.2204/ 1.1940 n.a. n.a. 32.379033 34.855960 -51.40122 2024-Nov-30 03:30 Nm 15 32 07.47 -22 19 36.9 112.542615 4.358444 n.a. n.a. 0.983648407806 0.9348431 0.00266942385911 -1.6442895 12.3299 /L 167.6368 0.2599/ 1.1793 n.a. n.a. 7.6329757 32.943343 -81.48105 2024-Nov-30 03:40 Cm 15 32 07.38 -22 20 39.2 111.651742 6.499757 n.a. n.a. 0.983652371130 0.9743686 0.00266272479369 -1.6374373 12.3373 /L 167.6295 0.2601/ 1.1650 n.a. n.a. 19.428905 188.66621 -69.09781 2024-Nov-30 03:50 Cm 15 32 05.35 -22 25 55.6 110.853205 8.686718 n.a. n.a. 0.983655707041 0.6309524 0.00265673695519 -1.2989002 12.3533 /L 167.6136 0.2213/ 1.1511 n.a. n.a. 43.242116 181.44014 -43.08726 >..... Daylight Cut-off Requested .....< >..... Solar Elongation Cut-off Requested .....< >..... Elevation Cut-off Requested .....< $$EOE *************************************************************************************************************************************************************************************************************************************************** Column meaning: TIME Times PRIOR to 1962 are UT1, a mean-solar time closely related to the prior but now-deprecated GMT. Times AFTER 1962 are in UTC, the current civil or "wall-clock" time-scale. UTC is kept within 0.9 seconds of UT1 using integer leap-seconds for 1972 and later years. Conversion from the internal Barycentric Dynamical Time (TDB) of solar system dynamics to the non-uniform civil UT time-scale requested for output has not been determined for UTC times after the next July or January 1st. Therefore, the last known leap-second is used as a constant over future intervals. Time tags refer to the UT time-scale conversion from TDB on Earth regardless of observer location within the solar system, although clock rates may differ due to the local gravity field and no analog to "UT" may be defined for that location. Any 'b' symbol in the 1st-column denotes a B.C. date. First-column blank (" ") denotes an A.D. date. CALENDAR SYSTEM Mixed calendar mode was active such that calendar dates after AD 1582-Oct-15 (if any) are in the modern Gregorian system. Dates prior to 1582-Oct-5 (if any) are in the Julian calendar system, which is automatically extended for dates prior to its adoption on 45-Jan-1 BC. The Julian calendar is useful for matching historical dates. The Gregorian calendar more accurately corresponds to the Earth's orbital motion and seasons. A "Gregorian-only" calendar mode is available if such physical events are the primary interest. NOTE: "n.a." in output means quantity "not available" at the print-time. SOLAR PRESENCE (OBSERVING SITE) Time tag is followed by a blank, then a solar-presence condition code: '*' Daylight (refracted solar upper-limb on or above apparent horizon) 'C' Civil twilight/dawn 'N' Nautical twilight/dawn 'A' Astronomical twilight/dawn ' ' Night OR geocentric ephemeris LUNAR PRESENCE WITH TARGET RISE/TRANSIT/SET EVENT MARKER (OBSERVING SITE) The solar-presence code column is immediately followed by another marker: 'm' Refracted upper-limb of Moon on or above apparent horizon ' ' Refracted upper-limb of Moon below apparent horizon OR geocentric The lunar presence marker (an ongoing state) can be over-ridden by a target event marker if an event has occurred since the last output step: 'r' Rise (target body on or went above cut-off RTS elevation) 'e' Elevation max (target body maximum elevation angle has occurred) 't' Transit (target body at or passed through observer meridian) 's' Set (target body on or went below cut-off RTS elevation) RTS MARKERS (TVH) Rise and set are with respect to the reference ellipsoid true visual horizon defined by the elevation cut-off angle. Horizon dip and yellow-light refraction (Earth only) are considered. Accuracy is < or = to twice the requested search step-size. 'R.A._____(ICRF)_____DEC' = Astrometric right ascension and declination of the target center with respect to the observing site (coordinate origin) in the reference frame of the planetary ephemeris (ICRF). Compensated for down-leg light-time delay aberration. Units: RA in hours-minutes-seconds of time, HH MM SS.ff{ffff} DEC in degrees-minutes-seconds of arc, sDD MN SC.f{ffff} 'Azi____(a-app)___Elev' = Airless apparent azimuth and elevation of target center. Compensated for light-time, the gravitational deflection of light, stellar aberration, precession and nutation. Azimuth is measured clockwise from north: North(0) -> East(90) -> South(180) -> West(270) -> North (360) Elevation angle is with respect to a plane perpendicular to the reference surface local zenith direction. TOPOCENTRIC ONLY. Units: DEGREES 'APmag S-brt' = The targets' approximate apparent visual magnitude and surface brightness. For planets and natural satellites, output is restricted to solar phase angles covered by observational data. Outside the observed phase angle range, "n.a." may be output to avoid extrapolation beyond the limit of model validity. For Earth-based observers, the estimated dimming due to atmospheric absorption (extinction) is available as a separate, requestable quantity. Surface brightness is the average airless visual magnitude of a square-arcsecond of the illuminated portion of the apparent disk. It is computed only if the target radius is known. Units: MAGNITUDES & MAGNITUDES PER SQUARE ARCSECOND 'r rdot' = The Sun's apparent range ("r", light-time aberrated) and range-rate ("rdot") relative to the target center, as seen by the observer. A positive "rdot" means the target center was moving away from the Sun, negative means moving toward the Sun. Units: AU and KM/S 'delta deldot' = Apparent range ("delta", light-time aberrated) and range-rate ("delta-dot") of the target center relative to the observer. A positive "deldot" means the target center is moving away from the observer, negative indicates movement toward the observer. Units: AU and KM/S 'S-O-T /r' = Sun-Observer-Target apparent SOLAR ELONGATION ANGLE seen from the observers' location at print-time. The '/r' column provides a code indicating the targets' apparent position relative to the Sun in the observers' sky, as described below: Case A: For an observing location on the surface of a rotating body, that body rotational sense is considered: /T indicates target TRAILS Sun (evening sky: rises and sets AFTER Sun) /L indicates target LEADS Sun (morning sky: rises and sets BEFORE Sun) Case B: For an observing point that does not have a rotational model (such as a spacecraft), the "leading" and "trailing" condition is defined by the observers' heliocentric ORBITAL motion: * If continuing in the observers' current direction of heliocentric motion would encounter the targets' apparent longitude first, followed by the Sun's, the target LEADS the Sun as seen by the observer. * If the Sun's apparent longitude would be encountered first, followed by the targets', the target TRAILS the Sun. Two other codes can be output: /* indicates observer is Sun-centered (undefined) /? Target is aligned with Sun center (no lead or trail) The S-O-T solar elongation angle is numerically the minimum separation angle of the Sun and target in the sky in any direction. It does NOT indicate the amount of separation in the leading or trailing directions, which would be defined along the equator of a spherical coordinate system. Units: DEGREES 'S-T-O' = The Sun-Target-Observer angle; the interior vertex angle at target center formed by a vector from the target to the apparent center of the Sun (at reflection time on the target) and the apparent vector from target to the observer at print-time. Slightly different from true PHASE ANGLE (requestable separately) at the few arcsecond level in that it includes stellar aberration on the down-leg from target to observer. Units: DEGREES 'T-O-M/MN_Illu%' = Target-Observer-Moon LUNAR ELONGATION angle and illuminated percentage. The apparent lunar elongation angle between target body center and Moon center, seen from the observing site, along with fraction of the lunar disk illuminated by the Sun. A negative lunar elongation angle indicates the target center is behind the Moon. Units: DEGREES & PERCENT 'RA_3sigma DEC_3sigma' = Uncertainty in Right-Ascension and Declination. Output values are the formal +/- 3 standard-deviations (sigmas) around nominal position. Units: ARCSECONDS 'Sky_motion Sky_mot_PA RelVel-ANG' = Total apparent angular rate of the target in the plane-of-sky. "Sky_mot_PA" is the position angle of the target's direction of motion in the plane-of-sky, measured counter-clockwise from the apparent of-date north pole direction. "RelVel-ANG" is the flight path angle of the target's relative motion with respect to the observer's line-of-sight, in the range [-90,+90], where positive values indicate motion away from the observer, negative values are toward the observer: -90 = target is moving directly toward the observer 0 = target is moving at right angles to the observer's line-of-sight +90 = target is moving directly away from the observer UNITS: ARCSECONDS/MINUTE, DEGREES, DEGREES Computations by ... Solar System Dynamics Group, Horizons On-Line Ephemeris System 4800 Oak Grove Drive, Jet Propulsion Laboratory Pasadena, CA 91109 USA General site: https://ssd.jpl.nasa.gov/ Mailing list: https://ssd.jpl.nasa.gov/email_list.html System news : https://ssd.jpl.nasa.gov/horizons/news.html User Guide : https://ssd.jpl.nasa.gov/horizons/manual.html Connect : browser https://ssd.jpl.nasa.gov/horizons/app.html#/x API https://ssd-api.jpl.nasa.gov/doc/horizons.html command-line telnet ssd.jpl.nasa.gov 6775 e-mail/batch https://ssd.jpl.nasa.gov/ftp/ssd/hrzn_batch.txt scripts https://ssd.jpl.nasa.gov/ftp/ssd/SCRIPTS Author : Jon.D.Giorgini@jpl.nasa.gov ***************************************************************************************************************************************************************************************************************************************************