Session 5: Focused Discussions—Missions in Definition

Mars Telecommunications Orbiter 2009

Chad Edwards

Mars Chief Telecommunications Engineer

Roger Gibbs

MTO Project Manager

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Mars Telecommunications Overview

• Communications is a key challenge for in situ exploration

– Earth-Mars link is 108 times further than a GEO comsat link

• Telecommunications relay orbiters offer high-rate, energy-efficient links for Mars exploration

1. Enabling and enhancing support for surface science operations

2. Robust capture of critical event communications

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1- Surface Operations Relay Support

Increased Data Return• Low-gain DTE: 3 kb/sol• MER-class DTE: 30 Mb/sol• ODY-class relay: 100 Mb/sol• MTO-class relay: 1-10 Gb/sol• Enables high-resolution in

situ science instruments

Increased Energy Efficiency

• Low-gain DTE: 500 W-hr/Mb

• MER-class DTE: 5 W-hr/Mb

• Relay: <0.1 W-h/Mb

• Enables small scout-class mission concepts; increases energy available for science

Increased Connectivity• Multiple comm contacts per

sol • Visibility to night side and to

poles (when Earth out of view)• Supports complex

in situ operations

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MER Data Return (Gbits)

6.2

67.2

3.2

MGS [8%] ODY [88%] DTE [4%]

Relay Performance for MER

• The MER mission has clearly demonstrated the value of relay telecommunicaitons– Over 75 Gigabits of data have

been returned from Spirit and Opportunity (as of 3 Nov, 2004)

– 96% of data return has been via UHF relay through ODY and MGS

“Cohokia” Panorama image, acquired by the Spirit Pancam instrument (588 Mbit compressed data volume)

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Sun SPK

Mars01

To Earth

Orbiter

Lander

2- Critical Event Communications

• In response to loss of Mars Polar Lander (‘98) during EDL (w/out any communications), MEP established a policy to require capture of engineering telemetry during future mission critical events – Provides critical feed-forward

information in the event of a mission anomaly

– Requires communications link availability under specific spatial and temporal constraints

– Data rate driven by bandwidth, complexity of engineering systems

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Instantaneous FootprintTotal Coverage(w/out Plane Change)

Critical Event Communications Challenge:At the Right Place, Right Time• Direct-to-Earth communications provides coverage of half of

planet, but at extremely low (~1 bps) data rates• Science orbiters can support high-rate telemetry, but with

extremely limited visibility– 400 km, polar orbit

– Constrained orbit node

• Higher altitude telesat can provide greatly increased coverage

Science Orbiter

High-Altitude Telesat

Orbit:400 km,

polar4500 km,

i=130º

Footprint: 3% 21%

Coverage: 31% 82%

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Program Strategy

• Provide evolutionary infrastructure growth at low cost by flying standardized proximity link payload on every Mars science orbiter

– MGS, ODY, MRO science orbiters

– Interoperability with international assets (e.g., Mars Express)

– Communications capabilities largely defined (i.e., constrained) by science-driven orbit characteristics

• Establish revolutionary infrastructure capabilities by deploying first dedicated Mars relay satellite: 2009 Mars Telecommunications Orbiter– Orbit selected to optimize

communications figures-of-merit

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Critical Event Monitor UHF:

1 - 16 kbps

Small Lander UHF:128 kbps (150 Mb in 20 minutes)

MER-C

lass

UHF:

128

kbps

(1 G

b/sol)

Directio

nal X-b

and:

1 Mbps (1

0 Gb/sol)

X-band: up to 4 Mbps(28 Gb/2 hrs)

X-band: 35-350 kbps

Ka-band: 0.35 - 4 Mbps

5 W Laser: 1 - 30 Mbps

Telecommunications Capability

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MTO as Technology Development Platform

In addition to its primary objective of serving as the Mars telecommunications satellite, MTO also provides a platform for two technology experiments:

- Optical communications from deep space- Deep space autonomous rendezvous

Mars Laser Communication Demonstration

Ground Terminal • 5m mirror at Mt Palomar• 4 element array (80 cm each)• Transmit a beacon and uplink

commands• Daylight operations

Flight Terminal • 5W Laser• Data rate 1 to 30 Mbps • Inertial / beacon pointing• Command at 10 bps

Rendezvous and Autonomous Navigation (RAN)Technology Demonstration

AutoNav:• Demonstrate autonomous Orbital Nav

using Mars landmarks, Phobos and Deimos.

• Supports Mars unmanned and manned safe and low-cost operational infrastructure.

RAN is composed of two linked elements:

Rendezvous:• Perform a rendezvous demonstration with

an Orbiting Sample Canister.

• Provides critical feed-forward to Mars Sample Return Mission.

Deimos

Landmark

Phobos

Orbiting Sample

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MTO Status

• Mission Concept Review successfully completed May 2004• Contractor selection in progress:

– Industry day conducted June 2004– Released Draft RFP, Final RFP– Proposals due December 3, 2004– Contractor selection, factfinding, negotiation and on contract: May 2005

• MLCD completed Mission Concept Review and System Requirements Review; Flight Terminal Peer Review; PDR scheduled for May 2005.

• Preliminary Mission System Review scheduled for September 2005.• Launch in 2009 requires significant coordination with MSL.• Design life of 10 years