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					   Assembly of a Large Modular Optical Telescope
    Segmented PrimAry RoboTic Assembly experimeNt


                                                    David W. Miller
                                                    Jason Budinoff

Massachusetts Institute of Technology
NASA Goddard Space Flight Center

     •     Increasing aperture sizes at GEO or ESL2 will require innovative robotic
           deployment-assembly methods
            – Unfolding, satellite tugs, robotic arms
     •     The associated complexity requires hardware-in-the-loop testing to truly
           understand the challenges and risks
            – Deployment-assembly is an inherently 3-D problem requiring -G testing
            – Paper studies will do little to manage this risk
            – Free-flyer, OE-like demonstrations are very expensive
     •     Is there a way to perform hardware-in-the-loop testing in -G at low risk
           and cost?

MIT Space Systems Laboratory                            2             Prof. David W. Miller (

• Develop a methodology for maturing in-
  space robotic assembly and phasing of
  telescopes using ISS.                                                          Telescope
• Through testing in -G, NASA & DoD
  will be better able to assess the true
  cost and complexity of this technology.

• Use the SPHERES satellite formation                                                 SPHERES
  flight and docking facility, currently on       US Lab on ISS
  ISS, to assemble a telescope with self-
  contained wave-front sensing & control.
• Possibly image Earth through optical
  window in US Lab.                           COMPARISON TO THE STATE OF THE ART
                                              •  The state-of-the-art for maturing technology is
EXPECTED PERFORMANCE                             simulation, 1-G hardware-in-the-loop testing,
• Robotic assembly of 1.2m diameter              and flight demonstration.
   telescope in one hour.                     •  Only flight demonstration can raise TRL to 7
                                                 and higher.
• Primary surface phasing to 100nm
                                              •  Demonstrations inside ISS cost ~1% of free-
• Execution of complete flight program for

MIT Space Systems Laboratory                  3                       Prof. David W. Miller (
                        SPHERES Formation Flight Laboratory

•   A risk-tolerant, flexible, high-fidelity environment to       Pressure                            Control Panel
    develop formation flight software                             Regulator                                     Ultrasound
     – 3 6-DOF free-flyer, self-contained nano-satellites; 2                                                    Sensors
         support satellites in ground operations               Pressure
     – Satellite-to-ground (laptop) and inter-satellite        Gauge
     – Custom pseudo-GPS metrology system
     – Guest Scientist Program supports multiple
     – Extensible via an expansion port
                                                                 Thrusters                                           Battery

                                                                             SPHERES nano-satellite
                                                                                  Beacons (5)
                                                                                                ISS Laptop

                                                                          SPHERES (3)
                                                                                                Courtesy Boeing Co

                                                                     SPHERES expected ISS Operations

MIT Space Systems Laboratory                            4                         Prof. David W. Miller (
                         Universal Docking Ports (UDPs)
•    Attach segments using docking ports
•    UDPs dock with copies of themselves
       –   Mature design already exists (bottom-left)
       –   UDP attaches to SPHERES expansion Port
       –   Have been used to dock two SPHERES
       –   Have been used to dock two sub-apertures
•    Can also incorporate robotic arm

MIT Space Systems Laboratory                            5   Prof. David W. Miller (
                          Have Already Tested Key Functions
                                        on ISS
               •   Activities aboard the ISS during 2006 (Test Session 1 to 8)
                     Area of Study            Active      Future                            ISS
                                                                     TS1 TS2      TS3    TS4 TS5         TS6      TS7      TS8
               Hardware Checkout                                      X   X        X      X               X
               Metrology                        X                     X   X        X      X     X
               Control                          X                     X   X        X      X     X          X        X        X

               Autonomy                         X                         X        X            X          X        X        X
               Artificial Intelligence                      X
               Communications                   X
               Human/Machine Interfaces                     X
               Docking: Basic                   X                       X    X     X      X       X        X
               Docking: Servicing, tumbling     X                                                 X        X        X        X

               Docking: Assembly                X                                                                            X
               Docking: Reconfiguration         X                                                                            X
               Separated Formation Flight       X                                  X      X       X        X        X        X
               Tethered Systems                 X
               Sample Capture                               X

               •   Results summary
                     –   Hardware checkout: Success             –   Formation flight, circular: Success!, ongoing
                     –   Sensor/actuator FDI : Success          –   Docking “safe”: Success!, ongoing
                     –   Estimation algorithms: Success         –   Docking “tumbling”: Success!, ongoing
                     –   On-line mass-ID: Success               –   Docking “assembly”: Success!, ongoing

MIT Space Systems Laboratory                                        6                         Prof. David W. Miller (
                          Assembled Telescope Concept
       •    Six-segment, spherical primary
            optical imaging telescope
       •    Each segment has
              – Tip, tilt, piston, and radius
              – Two UDPs to allow attachment
                to a SPHERE & telescope hub
                during assembly

                                                •   Source and Wavefront Sensing
                                                    at center-of-curvature
                                                •   Two SPHERES provide attitude
                                                    and station-keeping control
                                                •   Could image Earth through US
                                                    Lab optical window

MIT Space Systems Laboratory                    7                Prof. David W. Miller (
                          ALMOST-SPARTAN Telescope Detail

 1 of 6 identical
 segment trays

                                                    Secondary                        CC Source &
                                                    Mirror                           WFS Camera

Nanosat docked
to aft UDP

                                              Nanosat docked
                                              to foreware UDP

MIT Space Systems Laboratory              8                     Prof. David W. Miller (
                               Operational Concept

MIT Space Systems Laboratory             9           Prof. David W. Miller (
                                ALMOST ConOps
 •    Assembly                                 •    Upgrade
        – First SPHERE attitude and station-         – SPHERES expansion port allows
          keeps in center of US Lab                    additional payloads to be tested
        – Second SPHERE docks with                   – Add deployment capability
          component and moves it to final            – Add robotic manipulators
          location where it docks. Repeat.
                                               •    Organization
        – Third SPHERE with camera
                                                     –   MIT Space Systems Laboratory
          provides “eye-in-the-sky”
                                                     –   Payload Systems Incorporated
 •    Optical Phasing
                                                     –   NASA GSFC SPOT Team
        – Spherical primary
                                                     –   NRL Vision-Based Navigation
        – Center-of-curvature source and
          wavefront sensing                          –   Big Industry?
        – Primary hexagonal segments on tip-   •    Integration
          tilt-piston-stages                         – SPHERES integrated through DoD
 •    Robustness Testing                               STP with DARPA
        – Test nominal assembly                      – Integrate through STP or NASA
        – Introduce thruster, sensor, and      •    Funding
          communications channel failures            – NASA, NRO, DARPA
        – Revise S/W until GN&C is robust

MIT Space Systems Laboratory                   10                   Prof. David W. Miller (
                               Initial Stowed Configuration

MIT Space Systems Laboratory                 11          Prof. David W. Miller (
                               Primary Mirror Assembly

MIT Space Systems Laboratory               12        Prof. David W. Miller (
                               Primary Mirror Complete

MIT Space Systems Laboratory               13        Prof. David W. Miller (
                               Telescope Complete

MIT Space Systems Laboratory            14          Prof. David W. Miller (
                               ALMOST-SPARTAN Summary
  •    Potential Contributions                                  –   Only by gaining operational experience will
         –    Persistent imaging from GEO and large                 the DoD and NASA be able to properly
              telescopes at ESL2 require apertures                  judge the cost, risk and schedule
              much larger than available launch                     implications of this technology
              vehicle fairings
         –    Requires some form of complex               •    Innovativeness
              assembly/deployment.                              –   Uses existing facility in a risk-tolerant m-G
         –    ALMOST reduces time and cost                          environment
              required to mature such technology                –   Assembly tests take advantage of 3-D
         –    ALMOST is a method for rapidly testing                motion and sensor vantage points.
              prototype systems in -G at substantially         –   A free-flying on-orbit demonstration would
              reduced cost and risk                                 cost > $350M, causing program managers
         –    Analogous to a wind tunnel                            to naturally become more conservative.

  •    Nothing is better at managing the risks            •    Therefore, ALMOST-SPARTAN permits
       than hardware-in-the-loop testing in a                  full HIL system testing in long-duration
       representative (-G) environment.                       -G for ~1% of the cost of in-space flight
         –    To many people, the idea of robotic in-          demonstrations
              space assembly of large optical systems           –   It can be incrementally upgraded at
              is inconceivable due to cost and risk.                modest cost as promising technologies
         –    No series of paper studies is going to                emerge.
              reduce these concerns.

MIT Space Systems Laboratory                              15                        Prof. David W. Miller (

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