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09.2016

Meeting the Motion Challenges of Space Operation

Low Earth Orbiting Satellites The growth in the LEO satellite market continues to be driven by the continuous reduction in the cost to launch satellites as well as the ongoing efforts in component miniaturization. These efforts are resulting in many new satellite constellations, each potentially consisting of hundreds of satellites utilized for imaging and communication. As many of these satellites require motion or actuation, meeting the challenges for surviving launch and operation in space requires careful consideration to design, material section and performance criteria. Nanomotion continues to expand its motion activity in space applications related to both imaging and communication satellites, meeting the most demanding challenges for the operating environment and expected system life.

The Launch: During launch, Nanomotion’s motion systems, as any other part of the satellite, are subjected to non-operational shock and vibration. Applications may vary as to whether the system is allowed to move during this event, or if the system must maintain position, but system designs can accommodate for either scenario. LEO satellites are inherently expose to lower shock than MEO and GEO as the target altitude is lower. Typical Shock Spectrum: Typical Vibration Spectrum:

25g – 40g @ 100Hz 1000g @ 1kHz to 10kHz 10g rms for 120 seconds @ 20 to 2000Hz

The unique internal structure of Nanomotion’s piezo motors allows for the motor to withstand exceptionally high shock and vibration, without any internal damage. The piezo elements are supported on springs, with the motor tip & stage structure providing the ability to work like a clutch (sliding, as it is a direct drive), should the force in the direction of motion exceed the static holding force.

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Meeting the Motion Challenges of Space Operation

Shock & Vibration of a LEO Stage

>

x 10 -3

[g2/Hz] 3 orthogonal axes X, Y, Z

Random Vibration

20

11

150-280

80

280-320

300

320-380

200

380-850

100

850-1000

40

1000

22.5

2000

11

RMS VALUE DURATION

10.43

[g]

120

[s]

Typical Shock & Vibration Exposures: Linear acceleration 12g Harmonic oscillation 8 to 100Hz 3g Random Vibration 20Hz to 2000Hz 10grms Shock 1000g@1Khz , 25g@100Hz

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Meeting the Motion Challenges of Space Operation

The Operating Environment Temperature: All space rated systems are potentially exposed to a non-operational temperature of -55°C to +85°C. While it is possible that operational temperatures are at a similar range, typically the operational temperatures are in a narrower range, such as -10°C to +35°C. There are (3) primary considerations that relate to the operational temperature that Nanomotion takes into account: 1.The operating temperature range: This relates purely to the rating of the components and the system performance (precision) required. Managing the operation of the motors, encoders and drive electronics at the required temperature is essential. 2.The duty cycle of a motion system relates to the operating temperature as the application payload and the motors generate heat, the effect is manifested particularly in vacuum where heat dissipation is limited. Nanomotion has invested in the development of a variety of tools to expand the duty cycle, by managing the heat path. The use of high emissivity coatings and special materials to conduct a heat path away from motor operation have demonstrated significant benefits in stage operation and expanding the overall duty cycle. For all space applications, careful analysis and simulation are utilized to predict and guarantee the operation of the motion axes throughout the required duty cycle and life of the motion system. Nanomotion does a complete thermal analysis on both the stage and the electronics for each application to understand how the temperature variation may impact motion performance. The analysis is then confirmed by operation in a vacuum chamber and inspecting the temperature externally using a Thermal camera. 3.Thermal stress created by aggressive temperature cycles can impact a motion system. It is not simply a matter of operating between -10°C and +35°C, but these temperatures swing 16 times per day, resulting potentially in tens of thousands of thermal cycles, or more, mechanical stress is created at the motion assembly, the electronics, the soldering etc. It is essential that the mechanic design takes into account the fact that temperature swings will be often and aggressive when operating in space.

Thermal Analysis of Motion Systems

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Meeting the Motion Challenges of Space Operation

Thermal Analysis of Motion Systems

Conducting heat through moving parts and a bearing structure is considered to be a critical challenge for any motion system in vacuum. Nanomotion has developed a flexible and durable thermal conductive mechanism using sheets having thermal conductivity which is 4 times greater than copper sheets and 15 times the conductivity of pure aluminum foils. This mechanism was proven in vacuum tests for lifetime of >100M motion cycles.

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Meeting the Motion Challenges of Space Operation Thermal Analysis of Electronics

Nanomotion’s XCD Drive/Control Board

Nanomotion’s XCD Drive/Control Board

Nanomotion’s XCD Drive/Control Board

Radiation: While operation beyond the LEO satellite level will require Rad-Hard components, to survive the radiation levels, LEO satellite requirements have been less demanding. LEO Satellites can experience more aerodynamic drag over MEO and high orbit, but they are exposed to much lower radiation levels. A LEO Satellite may typically see a radiation dose of 1.0E-04 rad/sec, accumulating to 3.0E4 rad over a 10 year life span. As many of the LEO satellite applications demand a 3 to 5 year life, most commercially available components may prove suitable. Nanomotion has validated its drive and control electronics to meet 15kRad. RHA (Radiation Hardness Assurance) procedures defined by several MIL Specs will certify component selection for TID (Total Ionizing Dose), neutron displacement damage, and SEE (Single-Event Effects). While this may serve to guarantee the functionality of components, it does become a major cost driver. Nanomotion provides its customers with a detailed component BOM and has structured its drive/control boards to withstand LEO radiation levels for operation through 5 years. Nanomotion designs consider all materials that are utilized in the system design, mechanical and electrical, to assure operation based on radiation levels that the system is exposed to. The Motion: There is a common theme in all space applications, having to manage similar requirements for launch shock/vibration, in orbit temperature ranges and radiation. However each application presents different performance characteristics. Nanomotion carefully evaluates every application from a motion perspective, relative to precision, duty cycle, and operational life. All factors go through a thorough analysis, simulation and testing to assure operation in space. Nanomotion is currently meeting the needs of space applications as it relates to imaging and communication satellites. This includes linear, vertical, and rotary axes designed to meet the challenges of a demanding environment. While each motion system may be a different configuration, they each leverage the core components and technology needed to meet the application requirements. 5

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Meeting the Motion Challenges of Space Operation

The Motion: Throughout the range of applications, Nanomotion’s ultrasonic piezo motors and systems have demonstrated the flexibility and robustness to meet the requirements of space operation. Further to this, when compared against the range of motors cataloged by NASA, Nanomotion’s motors prove to have the most advantageous Power Density to Motor Weight.

Application Examples: Throughout the range of applications, Nanomotion’s ultrasonic piezo motors and systems have demonstrated the flexibility and robustness to meet the requirements of space operation. Further to this, when compared against the range of motors cataloged by NASA, Nanomotion’s motors prove to have the most advantageous Power Density to Motor Weight.

Application Examples: A three axis assembly (XY & Z) stage was developed for an imaging satellite system, to provide super resolution, with a high duty cycle (8Hz) operation. The stage uses one axis for moving an image sensor half a pixel, while the Z axis is used to focus.

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Meeting the Motion Challenges of Space Operation

Application Examples: (con’t) The stage must maintain a constant velocity at 8Hz to allow for image acquisition, throughout the temperature cycle. This stage utilizes coatings and other materials to manage the heat path to provide for extended operation of the system. The stage is designed to work for 3 years, supporting over 150 million cycles.

Summary: Recognizing that every space application represents different performance and operational requirements, Nanomotion motors and motion modules offer compact and precise designs, needed for space applications. Nanomotion has invested in developing core building block features that can be applied across a multitude of system designs. These capabilities create a library of tools that can be applied to the motion system design and the control system, allowing customers to leverage the success of ongoing space activity. When faced with the challenges of operating a motion system that cannot be serviced or maintained, Nanomotion has proven that its engineering capabilities and product technology are exceptionally well suited to meet these demands.

Nanomotion Ltd. Worldwide Headquarters Mordot HaCarmel Industrial Park Yokneam 20692 Israel t: +972 73 2498000 f: +972 73 2498099 e: [email protected]

Nanomotion Inc. U.S. Headquarters 1 Comac Loop, Suite 14B2 Ronkonkoma, New York 11779 t: (800) 821-6266 t: (631) 585-3000 f: (631) 585-1947 e: [email protected]

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