Using Commercial Off-The-Shelf Fuses in Vacuum

In the summer of 2015 during thermal vacuum testing of the Geostationary Operational Environmental Satellite-R series (GOES-R) observatory, a heater circuit that was part of the ground support equipment in the vacuum chamber developed an electrical short. The current flow through the short melted and vaporized approximately a meter of 14-gauge polytetrafluoroethylene (PTFE) insulated twisted pair copper wire. The test event was treated as a mishap, and an independent team investigated the failure. The mishap investigation team found as a contributing root cause that the test setup lacked sufficient circuit protection, and for future testing of the next three GOES-R observatories, they recommended the use of fusing or circuit interruption to protect the heater circuit wires [1]. In response to this recommendation, the GOES-R flight project traded two fusing options. One option was to locate the fuses for the wires inside the vacuum chamber, and the other was to locate the fuses external to the chamber. To support fusing inside the vacuum chamber, developmental testing of commercial off-the-shelf (COTS) fuses was initiated. Based on the heater circuit design, the testing focused on fusing 9 A at 250 V direct current (VDC) in both soft,130 Pa (1 torr), and hard, <30 mPa (2 10(exp 4) torr), vacuum conditions. If the selected fuses do not open a shorted circuit, then the test heater wires could vaporize again and cause another contamination event. If the fuses open below the required 9 A, then the spacecraft thermal vacuum testing campaign will be interrupted to open the chamber to replace test heater fuses

Investigation of Freeze and Thaw Cycles of a Gas-Charged Heat Pipe

The traditional constant conductance heat pipes (CCHPs) currently used on most spacecraft run the risk of bursting the pipe when the working fluid is frozen and later thawed. One method to avoid pipe bursting is to use a gas-charged heat pipe (GCHP) that can sustain repeated freeze/thaw cycles. The construction of the GCHP is similar to that of the traditional CCHP except that a small amount of non-condensable gas (NCG) is introduced and a small length is added to the CCHP condenser to serve as the NCG reservoir. During the normal operation, the NCG is mostly confined to the reservoir, and the GCHP functions as a passive variable conductance heat pipe (VCHP). When the liquid begins to freeze in the condenser section, the NCG will expand to fill the central core of the heat pipe, and ice will be formed only in the grooves located on the inner surface of the heat pipe in a controlled fashion. The ice will not bridge the diameter of the heat pipe, thus avoiding the risk of pipe bursting during freeze/thaw cycles. A GCHP using ammonia as the working fluid was fabricated and then tested inside a thermal vacuum chamber. The GCHP demonstrated a heat transport capability of more than 200W at 298K as designed. Twenty-seven freeze/thaw cycles were conducted under various conditions where the evaporator temperature ranged from 163K to 253K and the condenser/reservoir temperatures ranged from 123K to 173K. In all tests, the GCHP restarted without any problem with heat loads between 10W and 100W. No performance degradation was noticed after 27 freeze/thaw cycles. The ability of the GCHP to sustain repeated freeze/thaw cycles was thus successfully demonstrated

The Geostationary Operational Satellite R Series SpaceWire Based Data System Architecture

The GOES-R program selected SpaceWire as the best solution to satisfy the desire for simple and flexible instrument to spacecraft command and telemetry communications. Data generated by GOES-R instruments is critical for meteorological forecasting, public safety, space weather, and other key applications. In addition, GOES-R instrument data is provided to ground stations on a 24/7 basis. GOES-R requires data errors be detected and corrected from origin to final destination. This paper describes GOES-R developed strategy to satisfy this requiremen

Dither Gyro Scale Factor Calibration: GOES-16 Flight Experience

This poster is a sequel to a paper presented at the 34th Annual AAS Guidance and Control Conference in 2011, which first introduced dither-based calibration of gyro scale factors. The dither approach uses very small excitations, avoiding the need to take instruments offline during gyro scale factor calibration. In 2017, the dither calibration technique was successfully used to estimate gyro scale factors on the GOES-16 satellite. On-orbit dither calibration results were compared to more traditional methods using large angle spacecraft slews about each gyro axis, requiring interruption of science. The results demonstrate that the dither technique can estimate gyro scale factors to better than 2000 ppm during normal science observations

Essential SpaceWire Hardware Capabilities for a Robust Network

The Geostationary Operational Environmental Satellite R-Series Program (GOES-R) mission is a joint program between National Oceanic & Atmospheric Administration (NOAA) and National Aeronautics & Space Administration (NASA) Goddard Space Flight Center (GSFC). GOES-R project selected SpaceWire as the best solution to satisfy the desire for simple and flexible instrument to spacecraft command and telemetry communications. GOES-R development and integration is complete and the observatory is scheduled for launch October 2016. The spacecraft design was required to support redundant SpaceWire links for each instrument side, as well as to route the fewest number of connections through a Slip Ring Assembly necessary to support Solar pointing instruments. The final design utilized two different router designs. The SpaceWire standard alone does not ensure the most practical or reliable network. On GOES-R a few key hardware capabilities were identified that merit serious consideration for future designs. Primarily these capabilities address persistent port stalls and the prevention of receive buffer overflows. Workarounds were necessary to overcome shortcomings that could be avoided in future designs if they utilize the capabilities, discussed in this paper, above and beyond the requirements of the SpaceWire standard

On-Orbit Verification of GLM Navigation on GOES-16

The GOES-R flight project has developed the Image Navigation and Registration (INR) Performance Assessment Tool Set (IPATS) to perform independent INR evaluations of the optical instruments on the GOES-R series spacecraft. In this presentation, we document the development of navigation (NAV) evaluation capabilities within IPATS for the Geostationary Lightning Mapper (GLM). We also discuss the post-processing quality filtering developed for GLM NAV, and present example results for several GLM background image datasets. Initial results suggest that GOES-16 GLM is compliant with navigation requirements

On-Orbit Verification of GLM Navigation on GOES-16

The GOES-R flight project has developed the Image Navigation and Registration (INR) Performance Assessment Tool Set (IPATS) to perform independent INR evaluations of the optical instruments on the GOES-R series spacecraft. In this paper, we document the development of navigation (NAV) evaluation capabilities within IPATS for the Geostationary Lightning Mapper (GLM). We also discuss the post-processing quality filtering developed for GLM NAV, and present example results for several GLM datasets. Initial results suggest that GOES-16 GLM is compliant with navigation requirements

Observations from the GOES-R Solar UltraViolet Imager Extended Coronal Imaging Campaign

Solar corona in 17.1nm and 19.5nmwavelengths up to three solar radii from Sun center was observed by the Solar UltraViolet Imager (SUVI) on the Geostationary Operational Environmental Satellite (GOES) 16 and GOES-17. The nominally Sun-pointed SUVI was off-pointed to the left and to the right of the Sun center at a regular cadence and a composite Extended Coronal Imaging (ECI) frame was created. The imaging area in the composite is about three times the nominal image area in the East-West direction (about 5*R(sub Sun) versus 1.6*R(sub Sun) for nominal images). The campaign was conducted in February (4 hours), June (72 hours), and August-September of 2018 (5 weeks). Limited solar CME activity during the 5-week campaign was observed in both the SUVI and LASCO C2 imagers. Some of the observations during this campaign include structures up to a few solar radii off the solar limb, and interesting coronal activity both on and off the solar disk. They are presented here

An Overview of the Design and Development of the GOES R-Series Space Segment

The first of the National Oceanic and Atmospheric Administration (NOAA) Geostationary Operational Environmental Satellite R-series (GOES-R) satellites was launched in November 2016. GOES-R has been developed by NOAA in partnership with the National Aeronautics and Space Administration (NASA). The satellite represents a quantum leap in the state of the art for geostationary weather satellites by providing data from a suite of six new instruments. All instruments were developed expressly for this mission, and include two Earth-observing instruments (the Advanced Baseline Imager (ABI) and Geostationary Lightning Mapper (GLM)), two solar-viewing instruments (Solar Ultraviolet Imager (SUVI) and Extreme ultraviolet and X-ray Irradiance Sensors (EXIS)) and two in situ instruments (Space Environment In-Situ Suite (SEISS) and a magnetometer pair). In addition to hosting the instruments, GOES-R also accommodates several communication packages designed to collect and relay data for weather forecasting and emergency management. Accommodating the six instruments and four communication payloads imposed challenging and competing constraints on the satellite, including requirements for extremely stable earth and solar pointing, high-speed and nearly error-free instrument data transmission, and a very quiet electromagnetic background. To meet mission needs, GOES-R employed several technological innovations, including low-thrust rocket engines that allow instrument observations to continue during maneuvers, and the first civilian use of Global Positioning System-based orbit determination in geostationary orbit. This paper will provide a brief overview of the GOES-R satellite and its instruments as well as the developmental challenges involved in accommodating the instruments and communications payloads