Transcript STEREO Data System

Micro Arcsecond X-ray Imaging Mission
(Maxim) Pathfinder
Overview
John Martin
19 August 1999
Summary
 Maxim conceptual design presented here is an early design
which can be a baseline for further development
 Maxim requires a class of formation flying which is new to us
 Landsat-7 and EO-1 will fly in the same orbit with a controlled
separation, but no co-alignment on a common target
 Constellation-X will fly with multiple satellites in the same orbit,
co-aligned to a common target, but no separation requirement
 Other missions have proposed multiple satellites in slightly
different orbits, with separation managed but varying throughout
the orbit
 Maxim requires 2 satellites to be maintained with a fixed
separation and co-aligned for periods of as much as 7 days
 Maxim requires levels of pointing precision and stability which
are a challenge
Larger Concerns
 Flight Dynamics
 Selected use of drift-away orbit
 Simple cases appear to be manageable
 Not sure of the control authority required for the ±5° case
 Guidance, Navigation & control
 Appears feasible, provided the instrument is used to close the
loop for maintaining pointing stability
 More study needed of use of the pulse plasma thrusters
 More study needed of the post-launch scenario for separation and
orbit modifications needed to achieve final configuration
 Propulsion
 Can meet the pointing needs using a combination of coarse
(newton range) and fine (mnewton range) thrusters
 Slewing takes a lot of fuel
 Initial separation easier with 2 launch vehicles or a significant wait
(¼ to ½ orbit) after launch
Lesser Concerns
 Mechanical
 Can fit into a single launch vehicle with an extended fairing
 1 vs. 2 launch vehicles becomes a cost/propellant/wait-time tradeoff
 Conceptual design for launch and orbital deployed configurations
 Thermal
 Stable orbital environment leads to a straightforward design
 Concern exists that the ±5° pointing offset may produce a banana
effect on the optics satellite
 Further study of the potential use of a composite structure for the
optics satellite is indicated
 Power
 Full-sun leads to straightforward design
 Data Systems
 Data return from 40,000,000 km is possible using either 13m
dishes or the DSN 34m network
 C&DH approach based on the SMEX-lite design, but using a Power
PC 750 processor