mars telecommunications orbiter 2009
TRANSCRIPT
Session 5: Focused Discussions—Missions in Definition
Mars Telecommunications Orbiter 2009
Chad Edwards
Mars Chief Telecommunications Engineer
Roger Gibbs
MTO Project Manager
04/13/23 2
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
04/13/23 3
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
04/13/23 4
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)
04/13/23 5
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
04/13/23 6
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%
04/13/23 7
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
04/13/23 8
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
04/13/23 9
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
04/13/23 12
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