Developing the Explorer-1 [PRIME] Satellite for NASA s ELaNa CubeSat Launch Program David M. Klumpar Keith W. Mashburn Space Science and Engineering Laboratory Montana State University
Outline E1P Mission Overview Systems Engineering Challenges Assembly, Integration, and Testing Challenges Current Mission Status Future Mission Concepts Lessons Learned 21 April 2011 8th Annual CubeSat Developer's Workshop 2
Explorer-1 [PRIME] Mission The Explorer-1 [PRIME] (E1P) CubeSat mission demonstrates the utility of low-cost CubeSats to provide critical space weather observations for forecasting and specification Employs a simple Geiger Müeller tube to monitor the flux of trapped electrons in the horns of the inner and outer radiation belts with energies greater than approximately 60 kev Contributes to the development of the aerospace workforce by involving university students in spacecraft design, development, and operations 21 April 2011 8th Annual CubeSat Developer's Workshop 3
E1P: Monitoring the VAB E1P seeks to monitor the temporal and spatial distribution of energetic electrons confined along magnetic field lines Encounter radiation belt particles near the poles where magnetic field lines converge (the horns ) Counts NOAA POES Space Environment Monitor (>30keV electrons, -111W cross section) Latitude Data provided by Dr. David Evans NOAA SEC 21 April 2011 8th Annual CubeSat Developer's Workshop 4
Spacecraft Architecture The experiment consists of a collimated end-window Geiger tube Employs passive magnetic attitude control to align the GT perpendicular to the local magnetic field Utilizes a UHF transceiver for command and telemetry links Provides a continuous telemetry beacon for real-time SOH and particle observations 21 April 2011 8th Annual CubeSat Developer's Workshop 5
Standard CubeSat Developers Current paradigm for CubeSat development flows from the CubeSat Design Specification (CDS) Mandates fundamental interface, mass, and electrical inhibit requirements Provides only the minimum requirements to participate in a CalPoly-sponsored launch Verifiable requirements captured in CubeSat Acceptance Checklist (CAC) 21 April 2011 8th Annual CubeSat Developer's Workshop 6
Standard Developers Documentation 21 April 2011 8th Annual CubeSat Developer's Workshop 7
ELaNa Program Constraints Design requirements flow from ELaNa PPOD to CubeSat ICD In addition to CDS, ELaNA cubes must meet are requirements set forth in the ICD Additions include MSPSP, ODAR, ascent venting, transmitter characterizations, and many more Biweekly telecons with all ELaNa participants Formal requirement verification review administrated by ELaNa program management at L-3 months 21 April 2011 8th Annual CubeSat Developer's Workshop 8
ELaNa Power System Constraints Required the redefinition of being powered-off during launch Initially defined as no electrons flowing Final language required power system to be fully isolated from bus from time of integration into PPOD until deployment on orbit Required minor redesign of E1P flight system 21 April 2011 8th Annual CubeSat Developer's Workshop 9
ELaNa Power System Verification How do you verify the system remains in a power-off state? Incorporate CDH functions to monitor changes in power state during environmental testing Use RF receiver to monitor transmissions from the cube following vibration test Required minor redesign of E1P flight software 21 April 2011 8th Annual CubeSat Developer's Workshop 10
AI&T Challenges Required random vibe levels much higher than encountered on previous launches Required to perform shock testing on integrated PPOD 21 April 2011 8th Annual CubeSat Developer's Workshop 11
Shock Testing Pyrotechnic shock testing to simulate staging events during launch ascent Used EDU hardware for numerous test runs (~15) to achieve the required levels After level validation, performed test on flight PPOD with all three cubes integrated 21 April 2011 8th Annual CubeSat Developer's Workshop 12
Prior Vibration Testing 6.5 G rms NASA GEVS 14.1 G rms Reference Line at 0.1 G 2 /Root Hz Russian DNEPR 3.6 G rms 21 April 2011 8th Annual CubeSat Developer's Workshop 13
ELaNa Vibration Testing Nearly a factor of 10 increase from DNEPR and GEVS below 100 Hertz 16.4 Grms 2 min full levels in each axis Reference Line at 0.1 G 2 /Root Hz 21 April 2011 8th Annual CubeSat Developer's Workshop 14
Current Mission Status 21 April 2011 8th Annual CubeSat Developer's Workshop 15
Mission Status Due to a mechanical failure in the launch vehicle, Explorer-1 [Prime] Unit 1 failed to reach orbit Unit-1 now resides off the coast of Antarctica on the bottom of the Pacific Ocean 21 April 2011 8th Annual CubeSat Developer's Workshop 16
Where are we now? Flight Unit-2 has been in parallel development since Summer of 2009 Currently awaiting environmental qualification testing in May 2011 Final delivery of Unit 2 is July 25, 2011 E1P-Flight Unit-2 will be launched on 25 October 2011 along with the NPOESS Preparatory Project (NPP) aboard a Delta 2 from VAFB Flight Unit-2, Today 21 April 2011 8th Annual CubeSat Developer's Workshop 17
Future Mission Concepts 21 April 2011 8th Annual CubeSat Developer's Workshop 18
Future Missions TrackSat 21 April 2011 8th Annual CubeSat Developer's Workshop 19
Future Missions SubSat 21 April 2011 8th Annual CubeSat Developer's Workshop 20
Lessons Learned Need for detailed and organized configuration management is a must Must be willing to implement externallyimposed changes that may deviate from existing designs Build a spare flight unit Even the big boys can have a bad day 21 April 2011 8th Annual CubeSat Developer's Workshop 21
Questions? 21 April 2011 22 8th Annual CubeSat Developer's Workshop