Large-Scale Multidisciplinary Optimization of a Small Satellite’s Design and Operation

John T. Hwang, Dae Young Lee, James W. Cutler, and Joaquim R. R. A. Martins.  “Large-Scale Multidisciplinary Optimization of a Small Satellite’s Design and Operation“, Journal of Spacecraft and Rockets, Vol. 51, No. 5 (2014), pp. 1648-1663.
doi: 10.2514/1.A32751
The design of satellites and their operation is a complex task that involves a large number of variables and multiple engineering disciplines. Thus, it could benefit from the application of multidisciplinary design optimization, but previous efforts have been hindered by the complexity of the modeling and implementation, discontinuities in the design space, and the wide range of time scales. We address these issues by applying a new mathematical framework for gradient-based multidisciplinary optimization that automatically computes the coupled derivatives of the multidisciplinary system via a generalized form of the adjoint method. The modeled disciplines are orbit dynamics, attitude dynamics, cell illumination, temperature, solar power, energy storage, and communication. Many of these disciplines include functions with discontinuities and nonsmooth regions that are addressed to enable a numerically exact computation of the derivatives for all of the modeled variables. The wide-ranging time scales in the design problem, spanning 30 s to one year, are captured through a combination of multipoint optimization and the use of a small time step in the analyses. Optimizations involving over 25,000 design variables and 2.2 million state variables require 100 h to converge three and five orders of magnitude in optimality and feasibility, respectively. The results show that the geometric design variables yield a 40% improvement in the total data downloaded, which is the objective function, and the operational design variables yield another 40% improvement. This demonstrates not only the value in this approach for the design of satellites and their operation, but also promise for its application to the design of other large-scale engineering systems.Read More: http://arc.aiaa.org/doi/abs/10.2514/1.A32751

GRIFEX Flight Unit!

The GRIFEX team full assembled the flight unit for the first time yesterday.  See the pictures below.  Integration has been flawless so far and we are on schedule for a delivery of the flight unit in August to Cal Poly for launch integration.  This week will be performing a vibration test of GRIFEX and a shock test will be performed in a few weeks.  Launch is still holding for October.

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GRIFEX flight unit with a solar panel removed.

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GRIFEX flight unit.

MC2 in 2014 NASA Science Plan

nasa_science_2014MCubed-2 and its sister satellite, IPEX which was developed at Cal Poly, both appeared in the NASA 2014 Science Plan.  See page 98 of the full science plan.  CubeSats are mentioned throughout the plan as a tool for education, technology development, and potentially science.  The Heliophysics Research Program describes the Diversify, Real- ize, Integrate, Venture, Educate (DRIVE) initiative, which includes CubeSat flight opportunities.

GRIFEX coordinated by IARU

IARUMany thanks to the IARU team helping to coordinate global satellite frequencies.  GRIFEX was recently coordinated by them, and we will be operating at our typical MXL CubeSat frequency of 437.485.  GRIFEX launch is scheduled for the fall of 2014.  Follow this link to the IARU list of coordinated satellites.

MXL at the CubeSat Workshop

MXL is at the spring CubeSat workshop at Cal Poly in San Luis Obispo. Kathryn Luczek is presenting a poster on QB50. We are also part of several presentations, see below:

  • The Successful Operation of MCubed/COVE-2  – Paula Pingree @ JPL
  • Shields-1, A CubeSat With a Radiation Shielding Research Payload — Dr. Larry Thomsen @ NASA Langley
  • INSPIRE: Interplanetary NanoSpacecraft Pathfinder in Relevant Environment — Dr. Andrew Klesh @ JPL

If you’re at the workshop, stop by and say hello!