Radio Science (RS) using the

ULTRA STABLE OSCILLATOR

(USO)

Objectives:

Atmosphere

1. Determine Profiles of Refractive Index, Number Density, Temperature and Pressure at up to 20 meters Vertical Resolution for the Lowest Few Scale Heights at High Latitudes in Both Hemispheres on a Daily Basis for a Martian Year
2. Characterize the Small Scale Structure of the Atmosphere and Ionosphere

Gravity

1. Develop a Global, High-Resolution Model for the Gravitational Field
2. Determine Both Local and Broad Scale Density Structure and Stress State of Martian Crust and Upper Mantle

Instrumentation:

Spacecraft Telecommunications subsystem supplemented with an Ultrastable Oscillator and elements of the DSN tracking stations

Measurements:

• Signal Strength and Carrier Frequency
• Ultrastable Oscillator Provides Frequency Reference
• Frequency:
• 7164.624 MHz Uplink
• 8417.716 MHz Downlink (Closed Loop)
• 8416.368 MHz Downlink (In-Use Mode)
• Stability (Sq. Root of Allan Variance):
• 5X10-12 for 0.1 s Integration
• 1X10-12 for 1.0 s Integration
• 4X10-13 for 10 S to 1000 s Integration
• Electronics
• No Computer
• High Accuracy Clock Generator