Vibration Analysis of the Advanced Stirling Radioisotope Generators Tom Sutliff (for June Zakrajsek) NASA Doug Mehoke Applied Physics Laboratory Small Body Assessment Group July 11, 2012
ASRG Major Components and Interfaces Advanced d Stirling Radioisotope i Generator (ASRG) SBAG Meeting July 11, 2012 2
ASRG Component Status ASCs (convertors) E3s - first build of flight configuration The flight ASCs have completed their FDR (CDR) closeout, moving toward production (long leads were already authorized) The first of the final engineering (E3) series ASCs are completed and are in checkout testing ACU (controller) final engineering (EDU3) box is finishing its testing ASC ACU 3
ASRG Technical/Schedule Plans System Performance (mass, power, environments) still meets Discovery-12 commitments Component FDRs (CDRs) in process Generator Housing passed - Aug 2011 Convertors passed - Feb 2012 Controller review passed - May 2012 System FDR closeout - mid-july 2012 QU fabrication complete - Oct 2013 Two flight units to follow to DOE/Idaho National Lab Two fueled flight units to KSC ~Aug 2015 Typical flight development schedule margin in hand The ASRG development flow supports a January 2016 launch target 4
Hall System Development Milestone Status Projected Test Date HIVHAC thruster Performance Acceptance Test (PAT) CPE Power Processing Unit Vacuum Extended Operation Test (>500 hours) HIVHAC thruster Environmental (Vibration) Test GRC Completed December 2011 GRC Completed April 2012 GRC Completed May 2012 Xenon Feed System Delivery GRC Completed June 2012 BPT 4000 High voltage Wear Test JPL Scheduled September October 2012 HIVHAC thruster Environmental (Thermal Vacuum) Test HIVHAC Long Duration Wear Test Initiation JPL Scheduled November 2012 GRC Scheduled December 2012 Hall Performance Verification Tests GRC Being FY13Q1/2 (in High Vacuum Test Chamber) Planned Hall Propulsion System Integration Test Initiation GRC Being Planned FY15 SBAG Meeting July 11, 2012
Discovery Technology Development for Whipple: Reaching into the Outer Solar System PI: Charles Alcock, Smithsonian Astrophysical Observatory July 11, 2012 Less than 1 millionth of the volume of the solar system has been explored * Objects beyond the Kuiper Belt are too distant to visit, & too faint to observe directly This region will only be studied via the occultations of backgroundstars One candidate occultation event has been attributed to a small KBO The Whipple mission: Will monitor ~10,000 (20,000) stars @ 40Hz (20 Hz) to search for occultations by small objects (0.5 km KBOs; 5 *Schlichting et al 2009, Nature, 462, 895. Technology development plan is to build an end to end simulator of the Whipple photometer, including: Programmable LEDs to simulate stars undergoing occultation km Oort Cloud) between 40 AU and >10,000 AU events [done] Observed fields widely distributed over sky Simple lenses to represent Whipple optics [done] Stars imaged by a 77 cm Schmidt Cassegrain optic onto Teledyne CMOS detector with SIDECAR ASIC [in progress] a hybrid CMOS focal plane; field of view 6 o 6 o Real time on board photometry and event recognition on Photometry and light curve analysis (event search) FPGA board [in progress] performed on board because of high data rate Telemetry l to ground /full end to end d testing [Dec 2012] Version 1.0 of ground system analysis pipeline. [2013] Only candidate event data sent to ground for detailed analysis
PriME is a Proposed NASA Discovery Mission The proposal was selected in the last round of Discovery in Category 3, which provides technology funding for the mass spectrometer. It is not an actual accepted mission (yet!)
What is the range of chemical and isotopic diversity in the comet population? Is there any correlation between chemical ca composition o and nucleus physical properties? PriME will provide a detailed inventory of scores, if not hundreds, of volatile species.
Motivation: Cryo-trapping Requirements for 30% precision 36 Ar / 84 Kr Sample concentration Even though MBTOF is over 1000 times more sensitive than Cassini INMS (10x from ion source strength and 100x from better duty cycle), calculations show that it would take thirty six years to reach the desired precision through direct sampling. Cryo-trapping increases the signal and reduces the required analysis intervals for the most difficult components the noble gases - to ~40 hours. The cryo-trapping also increases ion source pressures to ~10-6 Torr, well above the anticipated i t chemical background seen on Cassini INMS, improving signal to noise for the analysis. Total analysis time (h hour) 1E+6 1E+5 1E+4 1E+3 1E+2 1E+1 >36 years analysis time without concentration 1E+0 1E+0 1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 Sample concentration factor
Cryo-trap Implementation Cryo-trapping Long established vacuum technique Freeze gas onto adsorber at 77K Uses space heritage Ricor cooler (used on CRISM, VIRTIS (Venus Express, Rosetta), VIR (Dawn), and Messenger Operation cycle Cool adsorber to 77K Open adsorber to gas Trap for required time Open adsorber to MBTOF Warm to release gas Near term development plan SwRI is in the midst of a very similar development program for space applications of cryo-trapping that will result in a TRL for the proposed cryo-trap before the due date of the MBC Discovery proposal. The cryo-trap has been shown in the previous viewgraph to be necessary to reach the sensitivity levels for the noble gas requirements from the RFI. Cold collimator excludes spacecraft atmosphere Sleeve valve rotates to select inlet or MBTOF Ricor cooler cold-finger Adsorber head cooled to 77K
MBTOF A Next Generation Mass Spectromete for Probing Solar System Formation