RADIO SCIENCE EXPERIMENTS OF JOINT OBSERVATION OF YH-1 AND PHOBOS-GRUNT Jinsong Ping, YH-1 VLBI team & RS team Shanghai Astronomical Observatory, CAS Nandan Rd. 80, Shanghai The second Moscow Solar System Symposium (2M-S 3 ) Moons of planets, IKI, Moscow, Oct.9-14, 2011

Df. Planetary Radio Science (RS) Science to investigate planetary atmosphere and ionosphere, gravity, mass(GM), ring, ephemeris, solar wind, comets, gravitational wave and red shift…mainly by measuring the change of phase, amplitude, polarization of the radio signal from S/C to ground station, which includes: Mass and gravity of planets and the moons ； Atmosphere: pressure, temperature, contents ； Ionosphere: electron density, corona, interplanetary media ； Testing experiments of general relativity; Orbit and rotation of the planets and moons ； Unification of celestial reference frames; Planetary surface by bi-static radar mode. Ref: Gavrik; Duev; Rosenblatt; Smirnov; Kosov; this meeting

Power Spectra of Mars Gravity Model Using DSN radio matrix data GGM1 GGM2b SHAO Solution Mars Gravity Model from MGS tracking data EXAMPLE01

Chinese VLBI Network For S/C POD Tracking Coverage: EW34° SN18° Baseline length: 1115km to 3249km MARK5B & CVSR Receivers; S/X/Ka EXAMPLE02

CE-1 Tracking Data Coverage On CLTM-s01 topography model Planetary Gravity: Improving Lunar Gravity by CE-1 Missions Gravity Error Spectral CEGM is 2 times better at low orders/degrees LP100k SGM100h CEGM50c Lunar DEM is improved by ~20meter with VLBI + RR&R POD data

MEX Open-loop RO mexmrs_0022, mexmrs_0024, EXAMPLE03

EXAMPLE04 a joint bi-static radar study by SHAO and JIVE

Applications RS in Chinese Martian exploration project YH-1  YH-1 will be YH-1 will be launched with Phobos-soil in November, 2011  Mission: 1.YH-1 will explore Martian space environment by in situ measurement and occultation with Phobos-Soil. A free-fly orbiter… 2.Two-point measurement will provide deep inside view of Martian space environment. 3.Only 1-way open-loop tracking and OD for YH-1 S/C

Scientific Objectives 1 To study in details of Martian space magnetoshpere, ionosphere and the plasma distribution and its variations - FGM, Plasma package, UHF receiver 2 To study Martian ions escape mechanism - Plasma package 4 To explore the Martian gravity field near equator - VLBI 3 To have a moderate survey of Martian surface topography and sandstorms – Visible light camera

Main Technical Specification Mass~110kg Body size750mm×750mm×600mm Power on orbit operation Long term ： 150W Short term ： 200W Orbit Type ： ellipse orbit Inclination ： 23 ～ 25° Apoapsis ： 400 ～ 1000km Periapsis ： ～ 80000km Attitude controlZero momentum three axis stabilization Electrical power Regulated bus Solar array, 4.674m 2,triple junction GaAs cells Lithium ion batteries 30AH TT&C X band ， CCSDS standard On-board computer31750CPU Thermal controlPassive control Reliability 0.65 （ EOL ） Lifetime1a

Introduction of the YH-1 mission situation Testing in 2008 & 2010:

craning for measurement center of gravity vibration test

Joint Russa-China Martion Missions: Phobos-Grunt & Yinghuo-1 (YH-1) after Zelenyi, this session

YH-1 &PGSC same beam VLBI observation to cancel Earth atm&iono effects, will success the single S/C RS observation in the joint missions. MARS Orbiter Phobos (Lander) VLBI-2 VLBI-1 1-way Doppler and D-VLBI only are used for OD and POD of YH-1 X-band 8.4GHz CWs are used. Earth Atm & Iono

Simple & Easy Onboard USO/clock is stable enough; Advanced Software Radio Tech; Save transferring time and resource Open Loop Tracking follow DLR-LP-1998

USO Stability For FGSC & YH-1 YH-1 is using a pair of USOs with long-term stability of 7x10E-11, may be improved by 1 order; 1x10E-12 for short term stability, same as FGSC

VLBI/CAS is powerful for deepspace S/C open-loop OD MEX OD ability test by new developed RSR of CVN 4ch, VLBI recording, RSR, Doppler & Phase retrieving

北京中心火星探测定器轨软件研制进展及精度初步分析 Based on OD and POD, the GM and low order/degree gravity for Mars and Phobos will be expected to be estimated and improved by the joint missions Mars gravity variation: Follow Konopliv, JPL/NASA

Working mode of bi-static radar to study Martian and Phobos surface characteristics

Planetary RO in Phobos-Grunt & YH-1 missions is possible to observe the day time and night time profiles of atm/iono at low latitude

VLBI Experiment Objectives in YH-1 & Phobos-Grunt mission To do OD and POD for YH-1 mission; To define more exactly Sun system’s parameters (Astronomical constant like GM and others, orbital parameters of Mars and Fobos); To study the Martian ionosphere using RS method; To study the Martian surface using bi-static radar method; To define more exactly limits of variation of universal gravitational constant; To define more exactly geometrical tie of dynamical coordinate system having original in Sun system mass centre of with coordinate system based on quasar angular coordinate measurements.

Also, following information of Phobos will be recovered by this joint mission: 1 ） Density by combining MEX figure with GM 2)Inner structure…ice or empty ? 3)Rotation/liberation (Main liberation with possible periods of ~24.6h, 12.3h, 7.55h, 3.78h, 184.3h, 92.2h, 38.2h, 19.1h need to measure.) 4)Orbit & Orbit evolution

Thank you