ai-aerospace/ams_data_full_2000-2020 huggingface dataset:
The MMS/SDP cover implementation is shown in Figure 9. The sensor sphere is titanium nitride, which  has a known photo-emissive property. It is required that the door restrain the sphere carefully and firmly so that there will be no wear or transference of material that would damage the performance of the sensor-sphere surface and degrade the performance of the sensor. The sensor sphere was pre-loaded to  178 N with three Ti6Al4V leaf springs and contacted through a Tecaform SD ring.  Testing SDO/EVE Mechanism Actuator Force Margin Test:   Early prototype testing (pre-PDR) was completed as a way to establish  the force margin for the actuator and torque margin for the hinge springs. Figure 10 shows the setup and  results of this early test. A prototype mechanism was placed in a thermal oven and purged with N 2. The  actuator was removed for this test and substituted with a hand held force gage to measure the force required to unlatch and deploy the mechanism. This wasn’t the perfect test – the oven door was opened  repeatedly during the measurements which resulted in some frost build up. Dry ice was used to cool past the oven’s cold temperature capability. Although this wasn’t a perfect flight-like environment, it was  considered very useful as a simple way to gain confidence, early in the mechanism development. The maximum force required to unlatch the mechanism was 6 N, which is very low considering the actuators 156-N capability.    Hinge line friction test: All mechanisms had hinge drag torque measurements performed during  assembly, and had corresponding spring torque measurements completed after assembly. This verified a  positive margin of safety for deployment torque. 1G Orientation deployment:   One of the mechanisms was deployed in all six orientations, with respect  to gravity, with no anomalies. 8
Atm. Temp  CForce to release N (lb) 10 cycles Air 22 6 (1.3) Hot N2 50 6 (1.3) Cold N2 -39 6 (1.3) Cold N2 -33 5 (1.2)Cold N2 -49 5 (1.1) Cold N2 -62 6 (1.5) Hot N2 +50 3 (0.7) Actuator Capability 156 (35.) Figure 10.  Aperture Co ver Force MarginDry Ice Aperture Cover Mechanism in  thermal oven, with N2 purge Final Run-In test: All four flight mechanisms were deployed in a vacuum tank 45 times each in a matrix  of 3 voltages and 3 temperatures for both primary and redundant windings. The deployment time was  recorded for each actuator and typical values are noted in the table in Figure 11. The large variation in  deployment times prevents a software time-out from being an effective method to power off the HOP. This result reaffirmed the necessity of end of travel switches.  Figure 11.  Run-In TestDeployment time (s) Temp 22V 28V 35V -30 C 490 228 121 20 C 216 117 6940 C 131 80 50 Figure 12.  Switch Spring M easurements Switch Anomaly: During the run-in test, one limit switch on one mechanism failed to properly indicate  “door open” after 17 cycles. If this had happened in flight, it would neither have prevented the door from  properly opening, nor prevented the actuator from being powered off. Nonetheless, the test was paused  and the root cause was investigated. Measurements of the height of the “end-of-travel” spring and the “switch spring” were made (Figure 12),  and it was found that variations in the height of these 2 springs could prevent the switch from being fully  depressed. The “end-of-travel” spring was shimmed to match the other mechanisms. The shimmed  mechanism was then manually deployed 25 times in air at room temperature with zero anomalies. At this  point, the final run-in test was resumed with no further issues. Vibration Testing:  An early prototype installed on a mass model was vibration tested to 10.0 grms and  acoustic tested to 142 dB. The final flight mechanisms were vibration and acoustic tested after installation  on the flight instrument.   9
Testing MMS/SDP Mechanism The engineering model was vibration tested with the integrated instrument. Following the test, the cover  was deployed 14 total times, with 1 actuation at +50 /g113C and 3 actuations at -30 /g113C. These deployments  were done in thermal convection chambers. The EQM was also vibration tested on the integrated  instrument, followed by 23 total actuations. During TVAC, the unit was successfully deployed at both cold  and hot survival limits. To date, a total of 16 flight units have undergone vibration and thermal vacuum  testing. The only resulting anomaly was determined during a safe-to-mate check, and was related to a micro-switch. During the entire test campaign there has not been any premature deployments and all planned door actuations have been successful. Figure 13.  MMS/SDP Latches On-orbit experience SDO/EVE covers were successfully deployed on orbit with no issues. The MMS/SDP covers are  integrated onto the spacecraft, ready for launch. Conclusion The SDO/EVE mechanism was a robust design that was easily scaled to a highly preloaded application  for MMS/SDP. Building and testing the assembly early allowed for resolution of design issues associated with the original end-of-travel catch design. The capability of removing the actuator proved very helpful for  testing the latch release force. Performing a run-in test over survival limits with many cycles was an  effective way to uncover a limit switch adjustment issue, and provided a high degree of confidence in the design. 10
Metering Wheel-Wire Track Wire Boom Deployment Mechanism Mark S. Granoff* Abstract  The NASA MMS Spin Plane Double Probe (SDP) Deployer utilizes a helical path, rotating Metering Wheel  and a spring loaded Wire “Holding” Track to pay out a “fixed end” 57 meter x 1.5 mm diameter Wire Boom  stored between concentric storage cylinders. Unlike rotating spool type storage devices, the storage  cylinders remain stationary, and the boom wire is uncoiled along the length of the cylinder via the rotation  of the Metering Wheel. This uncoiling action avoids the need for slip-ring contacts since the ends of the wire can remain stationary. Conventional fixed electrical connectors (Micro-D type) are used to terminate to operational electronics.  Figure 1. SDP x-section, Wire Boom (green) between stationary cylinders & exiting on axis Introduction The original concept for this mechanism was first put forth by the Royal Institute of Technology (KTH)  Stockholm, Sweden 1. Engineering and manufacturing limitations at KTH necessitated the support of a  strong design and flight fabrication capable institute to make SDP a reality. Collaboration with the University of New Hampshire Space Science Center was initiated and a competitive proposal was won,  landing this challenging project and bringing this instrument from concept level to flight deliverable  hardware in less than 36 months. A total of 16 flight-qualified SDP Deployers have been integrated,  tested and delivered to NASA for the upcoming MMS mission. The unique approach toward wire coil storage and deployment provided by this instrument is the impetus for writing this paper. Metering Wheel & Wire Track Background The Metering Wheel is keyed to the Metering Wheel Shaft which is supported in the instrument “Back  Plate” via an integral Hub Bearing (journal type) made from SP-3 Vespel for low friction and good load carrying capacity. A Bellville washer and pre-load nut combine to provide a consistent pre-load of the  *University of New Hampshire, Space Science Center, Durham, NH /g51/g85/g82/g70/g72/g72/g71/g76/g81/g74/g86/g3/g82/g73/g3/g87/g75/g72/g3/g23/g21/g81/g71/g3/g36/g72/g85/g82/g86/g83/g68/g70/g72/g3/g48/g72/g70/g75/g68/g81/g76/g86/g80/g86/g3/g54/g92/g80/g83/g82/g86/g76/g88/g80/g15/g3/g49/g36/g54/g36/g3/g42/g82/g71/g71/g68/g85 /g71/g3/g54/g83/g68/g70/g72/g3/g41/g79/g76/g74/g75/g87/g3/g38/g72/g81/g87/g72/g85/g15/g3/g48/g68/g92/g3/g20/g23/g16/g20/g25/g15/g3/g21/g19/g20/g23/g3 11
Metering Wheel Shaft into the hub bearing. A polycarbonate cover, a polished stainless steel conduit tube  and PEEK Exit Ferrule complete the subassembly.  Figure 2. MMS SDP Metering Wheel Back Plate Sub-Assembly The Metering Wheel has opposing conduit ramps which simultaneously load the wire into the wire holding track, and uncoil the wire from the track. A hard-coat anodized “Outer Race” provides the reaction surface for the wire while under spring load in the track. As the wire moves relative to the metering wheel, the  coils transition from the track and are linearly displaced within a helical tube conduit along the instrument principle axis. This mechanism operates clockwise and counterclockwise dependent upon commanded  “deployment” or “stowage.”   Figure 3.  SDP Metering Wheel, Conduit Ramps A key aspect of this instrument application is the ability of the Metering Wheel and Track to adequately  hold the sphere and wire boom when exposed to the maximum centrifugal acceleration of the rotating MMS satellite. As calculated by the instrument P.I. P-A Lindquist 2, KTH, this applied load is 5.22 N  (1.17 lb) and occurs during spin up. Although a modest value, quantifying the load carrying capability of the SDP Metering Wheel & Track became paramount to design approval going forward. Early simplified models with high friction silicone races showed promise in generating holding power; however deflections of the non-linear elastomeric silicone, and unknown friction values were not quantifiable, leading to an ambiguous assessment of Metering Wheel & Wire Track load capability.  12
To quantify the load in the track, a series of simple, integral radial leaf springs, were machined into the  PEEK Holding Track at an un-deflected radius. When the wire is loaded into the PEEK Track, the leaf  springs deflect and a resultant spring load is generated for each spring, holding the wire in compressionagainst the hard-coated Outer Race. The springs are implemented in opposing pairs so that the track will  work equivalently for both deployment and stowage rotations. Shown in Figure 4 is a developmental one-piece track/race depicting the spring deflection and subsequent compression reaction against the outer race. Figure 4. PEEK Holding Track - spring de flection w/Wire (non-flight hardware) The following expression from Spott’s 3Fig. 1-13-5 is used to calculate the load generated by each spring  deflection: Spring load = (Y max × 3 × E × I)/L3 (multiply result by number of active springs)   Where:  Ymax= deflection of spring 0.3 mm (0.012 in)  E    = Young’s Modulus for PEEK  I = MOI for Spring Section (bh3/12)  L = length of spring arm Due to the overlapping ramps of the Metering Wheel, about 259° (of 360°) of the of the Track, and hence  springs, are active at any given moment. This results in 22 active springs for a total Normal load “ N” of  about 25 N (5.6 lb). Implementing the expression F=μ ×N with μ of PEEK4being about 0.3, the load in the  track ( F=T T) is calculated as about 7.5 N (1.7 lb). If the track was a linear or straight device, that would be  your holding power. However, with the circular geometry of the Metering Wheel and Track, a “band brake”  analogy is drawn and allows us to calculate the additional load holding capability of the Metering Wheel  and Track via the following expression: TS= T T × e/g151/g302   (Spott’s Eqn. 18, 5thEdition, Chap. 6) Where:   TS= load holding capacity at SDP Sphere end of wire boom, N (lb)    TT= load in Track via spring normal force, friction coeff. & qty of active springs, N (lb)    μ= Friction Coefficient of PEEK, 0.3   /g302= 259° Boom wrap angle in track, = (259/360) /g238/g3/g21/g652/g3/g32/g3/g23/g17/g24/g21   /g151/g302= 0.3×4.52 = 1.357  13
Solving yields: TS= 28.5 N (6.4 lb)  This resultant load capacity of the SDP Metering Wheel and PEEK Wire Holding Track provides  significant margin over the applied centrifugal load generated by the MMS spin rate. Load testing carried out with the SDP gear train engaged, i.e., with the Metering Wheel main gear locked through the engaged  gear train all the way to the stepper motor pinion, yielded a pull test value of over 90 N (20 lb). This  testing demonstrated analytical conservatism, and that there exists additional friction sources in our mechanism contributing to this robust margin for the flight assembly.  Figure 5. MMS SDP Metering Wheel Pull Test slips at 21.6 lb (96 N) Stress  The individual springs can be treated as classic cantilever beams with bending stress calculated via: Sb= MC/I  Where: M = bending moment of load P at deflection x moment arm length L    C = distance to neutral axis of spring   I = MOI for Spring Section (bh 3/12) Solving yields 25.5 MPA (3700 psi) stress With PEEK 450G having a tensile stress limit4of 97 MPA (14065 psi) and considering the NASA standard  calculation for margin of safety, MSY >0:  MSY = [mat’l limit/(1.6 x applied stress)] -1 = [97/(1.6 x 25.5)]-1 = 1.37>0  With this resultant >0, the stress margin is acceptable. Fatigue Figure 6 depicts the Victrex PEEK 450G fatigue curve5. Extrapolating for 25.5 MPA, cycles to failure for  the SDP Wire Track springs should exceed 10e7 cycles. With each 57 meter SDP deployment, each  spring sees approximately 170 actuations. With the Engineering Qualification Model demonstrating 14 complete deployments, along with 14 stowage cycles, the life test unit springs experienced more than 4700 actuations. With this significant margin of cycles to failure, and with the demonstrated life testing  margin at 3.5 X flight model total actuations, fatigue of the PEEK Wire track springs is not considered  significant.  14
Figure 6. Victrex PEEK Fatigue Curve, 450G Thermal Considerations During developmental thermal testing at UNH6it was determined that there was too large a mismatch in  Coefficient of Thermal Expansion (CTE) between the Habia Boom Wire (27.9e-6/°C) and the original PEEK (42.4e-6/°C) outer race feature leading to deployment of “small coils” during cold plateaus. The resultant was a binding of the coils along the inner storage cylinder. Subsequent testing determined that the CTE of the Habia wire was very close to that of Aluminum (23.4e -6/°C) and the outer race feature was  implemented into a separate part, a hard coat anodized Aluminum Outer Race. With CTE’s for the Habia wire, Outer Race and Inner Cylinder now all matched, successful thermal deployments were achieved. Integration of the PEEK Track and Aluminum Outer Race into the SDP Back Plate is shown in Figure 7.  The 16 pairs of opposing springs are relieved toward the Back Plate to allow unimpeded (non-rubbing) deflection. The track is held in place via 16 miniature M1.6 metric screws that thread directly into tapped  holes in the track. Note the Vespel Hub Bearing shown installed at the Back Plate center.   Figure 7. PEEK Wire Holding Track & Outer Race installed in SDP Back Plate (flight hardware) 15
Boom Wire The Wire used for the SDP Boom is manufactured by Habia Cable in Soderfors, Sweden7. Habia  provided a custom 7 conductor, Kevlar/Kapton overwrap layup with a silver-plated copper GND shield. UNH worked closely with Habia to tailor the mechanica l characteristics of the layup to ensure optimal  consistency in cross sectional diameter as well as overwrap stiffness. The nominal diameter of the  composite wire was specified to be held within 1.50 mm ± 0.05 mm, critical for consistent spring deflection in the PEEK Track/Outer Race geometry. Inspection data from Habia via laser measurement of each spool of wire for SDP demonstrated even tighter control of this important aspect of the wire. A sample plot  of this diametral inspection is shown in Figure 8 8. This modest actual variation in diameter, +0.02 mm /   -0.01 mm was typical for SDP flight spools. Figure 8. Habia Boom Wire inspection data, diameter variation over 70 meter spool Material Specifications The materials used in manufacturing the SDP Metering Wheel and Wire Track sub-assembly were  optimized during the comprehensive, and flight fide lity engineering model development at UNH. Surface  treatments were optimized for friction and wear; all materials meet the stringent NASA Reference Publication 1124 for outgassing of materials intended for spacecraft use 9. The materials list follows: /g120Metering Wheel - 7075-T7351 Aluminum w/General Magnaplate Tufram low friction plating /g120Wire Track- PEEK Victrex 450G /g120Hub & Thrust Bearings - Dupont Vespel SP-3  /g120Outer Race - 6061-T6 Aluminum w/clear hard-coat anodize /g120Conduit Tube - 300 SS tube, custom formed and internally polished /g120Belleville Spring - BeCu heat treated /g120Cover - Lexan Polycarbonate /g120Ferrule - PEEK Victrex 450G /g120Nut & Key Pin - 6AL-4V Titanium /g120Back Plate - 7075-T7351 Aluminum w/black hard-coat anodize /g120Shaft - 7075-T7351 Aluminum w/black hard-coat anodize 16
Testing Comprehensive full deployment testing and powered stowage of each 57-meter SDP Boom is conducted  at several junctures during flight integration and testing resulting in a minimum of 4 complete deploymentsand stowage operations. Developmental testing for life assessment was conducted on the flight-like Engineering Qualification Model which demonstrated 14 complete deployments and powered stowages, ensuring adequate margin over flight for the Metering Wheel-Wire Track deployment mechanism. Figure 9. MMS Flight Model SDP depl oyment testing, UNH vacuum chamber Conclusions The successful integration, test and delivery of the 16 MMS SDP instruments validated this unique  approach to Wire Boom Deployer design. The integral Wire Track springs allowed quantification of the  load in the track, and the Metering Wheel un-coiling rotation allowed the use of stationary storage  cylinders and fixed electrical terminations.  Figure 10. Flight Model MMS SDP instrument s, fixed Wire Boom Termination at left 17
References 1. Göran Olsson, Royal Institute of Technology (KTH), “SCALE-UP Wire Boom Deployment  Mechanism, Stockholm 2007” 2. Per-Arne Lindqvist, Royal Institute of Technology (KTH), “MMS SDP Wire Boom Deployment  Plan” (15 February 2008)  3. M.F. Spotts, Design of Machine Elements, 5thEdition, Chapters 1 & 6 Section 9. Band Brake 4. Victrex PEEK Material Properties Guide, Table 2 & Figure 30 450G5. Victrex PEEK Material Properties Guide, Figure 14, 450G plot 6. Ivan Dors, Garrett Roy, “EM SDP CTE Measurement Summary Revised,” (28 September 2010) 7. H. Bertilsson, Habia Cable specification drawing 700016945 (2010-03-11) 8. B. King, UNH Project Manager, Habia Inspection Log, (26 October 2011)9. NASA Reference Publication 1124, Outgassing Data for Selecting Spacecraft Materials 18
Development of Cryogenic Filter Wheel s for the HERSCHEL Photodetector Array  Camera & Spectrometer (PACS) Christian xKörner*, Dirk xKampf* ,Albrecht xPoglitsch**, Josef Schubert**, U. Ruppert+and M. xSchoele+ Abstract This paper describes the two PACS Filter Wheels that are direct-drive rotational mechanisms operated at  a temperature below 5K inside the PACS focal plane unit of the Herschel Satellite. The purpose of the mechanisms is to switch between filters. The rotation axis is pivoted to the support structure via a slightly  preloaded pair of ball bearings and driven by a Cryotorquer  [1]. Position sensing is realized by a pair of  Hall effect sensors. Powerless positioning at the filter positions is achieved by a magnetic ratchet system. The key technologies are the Cryotorquer design and the magnetic ratchet design in the low temperature range. Furthermore, we will report on lessons learned during the development and qualification of the mechanism and the paint.  Introduction and Requirements HERSCHEL is an ESA Cornerstone mission to study the origin and evolution of stars and galaxies. Three  cryogenic instruments are accommodated in the focal plane of the Herschel telescope: HIFI, SPIRE and PACS. The giant infrared space observatory was launched on 14 May 2009 on an Ariane 5 and successfully operated in an orbit around L2 until end of April 2013, when the cryostat ran out of liquid  helium coolant. The PACS instrument operates either as an imaging photometer or an integral field /g86/g83/g72/g70/g87/g85/g82/g80/g72/g87/g72/g85/g3 /g82/g89/g72/g85/g3 /g87/g75/g72/g3 /g86/g83/g72/g70/g87/g85/g68/g79/g3 /g69/g68/g81/g71/g3 /g73/g85/g82/g80/g3 /g24/g26/g3 /g87/g82/g3 /g21/g20/g19/g3 /g541/g80/g17/g3 /g44/g81/g86ide the PACS instrument, several  mechanisms are accommodated:  a Chopper to switch between the sky field of view and internal calibration sources, a Grating Drive to scan through the spectral band, and two Filter Wheels to select  spectral bands for the observation which are subject of this paper. The main requirements for the Filter  Wheels are listed in Table 1.  Table 1: Filter Wheel Main Requirements Requirement Mass Max. 1000 g Quasi-static load 25g No of revolutions incl. ground test  and ECSS margins (qualification @ LHe)40000 Operational temperature range 1K…350K Amount of Filters 2 (initially 4) Switching time (180°) 5 sec Powerless position preservation ±30 arcmin (0.5 Ncm @3°) Stray light reduction (on instrument level) 108 Power dissipation 4K level: 50 mWs per switching * Kayser-Threde GmbH, Munich, Germany **  Max Plank Institut für extraterrestrische Physik, Garching, Germany +Freie Universitat Berlin, Berlin, Germany /g51/g85/g82/g70/g72/g72/g71/g76/g81/g74/g86/g3/g82/g73/g3/g87/g75/g72/g3/g23/g21/g81/g71/g3/g36/g72/g85/g82/g86/g83/g68/g70/g72/g3/g48/g72/g70/g75/g68/g81/g76/g86/g80/g86/g3/g54/g92/g80/g83/g82/g86/g76/g88/g80/g15/g3/g49/g36/g54/g36/g3/g42/g82/g71/g71/g68/g85 /g71/g3/g54/g83/g68/g70/g72/g3/g41/g79/g76/g74/g75/g87/g3/g38/g72/g81/g87/g72/g85/g15/g3/g48/g68/g92/g3/g20/g23/g16/g20/g25/g15/g3/g21/g19/g20/g23/g3 19
Accommodation In order to reduce the amount of sliding, rolling or flexing parts and due to mechanical and optical  envelope reasons, a rotating system with a rotating cone supporting the filters was selected. The bearings  are accommodated around the center of gravity of the rotating mass. The rotor of the Filter Wheel drive  acts as a counterweight to the mass of the Filter Wheel and filters. To keep the wheel assembly compact,  the position sensors and the magnetic ratchet system are accommodated in one plane with the lowerbearing. The Filter Wheel drive, which was provided by FU Berlin, consists of a two-part rotor equipped with two sets of permanent magnets on both sides of the coils and a stator that is locatred between the  magnets of the rotor and carries the windings (see Figure 6).  Figure 1. Filter wheel configuration Bearing system The bearing is located in between the filters and the rotor of the motor. This allows a counterweighted  configuration of the movable parts. The Filter Wheel with all the rotating parts (Cryotorquer Rotor, Wheel  cone, Filters Axis…) has a mass of <600 g. The maximum quasi-static acceleration (derived from the Instrument FEM) is 26 g. To avoid gapping of the bearing, a preload of 126 N would have to be applied.  But since the wheel shall be optimized to run with low power dissipation ( 50 mWs per switching), the  preload is reduced to a minimum and the higher amplification and friction (during vibration) in the bearing  is taken into account by a higher load capability. The selected bearing configuration is an O-configuration  of two GRW SS6900 Z C10/15 GPR-1 J ball bearings. Figure 2. Gold-lubricated GRW SS6900 Z C10/15 GPR-1 J Ball bearing 20