Engineering topics

Sabelhaus, Phil

Publications and source records attributed to Sabelhaus, Phil.

7 records

NASA NTRS2012

Progress Towards a 2012 Landsat Launch

The Landsat Data Continuity Mission (LDCM) is on schedule for a December 2012 launch date. The mission is being managed by an interagency partnership between NASA and the U.S. Geological Survey (USGS). NASA leads the development and launch of the satellite observatory while leads ground system development. USGS will assume responsibility for operating the satellite and for collecting, archiving, and distributing the LDCM data following launch. When launched the satellite will carry two sensors into orbit. The Operational Land Imager (OLI) will collect data for nine shortwave spectral bands with a spatial resolution of 30 m (with a 15 m panchromatic band). The Thermal Infrared Sensor (TIRS) will coincidently collect data for two thermal infrared bands with a spatial resolution of 100 m. The OLI is fully assembled and tested and has been shipped by it?s manufacturer, Ball Aerospace and Technology Corporation, to the Orbital Sciences Corporation (Orbital) facility where it is being integrated onto the LDCM spacecraft. Pre-launch testing indicates that OLI will meet all performance specification with margin. TIRS is in development at the NASA Goddard Space Flight Center (GSFC) and is in final testing before shipping to the Orbital facility in January, 2012. The ground data processing system is in development at the USGS Earth Resources Observation and Science (EROS) Center. The presentation will describe the LDCM satellite system, provide the status of system development, and present prelaunch performance data for OLI and TIRS. The USGS has committed to renaming the satellite as Landsat 8 following launch.

Irons, Jim↗

NASA NTRS2010

Managing Complex Space Missions Like the James Webb Space Telescope

Program Management Summary; Organizational structure is established. Roles and responsibilities are well defined: a) All major contracts are in place. b) All foreign partners are in place, operating under signed Memoranda of Understanding (MOUs). c) Partners include GSFC, NGST, Ball, ITT, ATK, STScI, ESA, CSA, UAz, LM, JPL, MSFC, ARC, JSC, etc. All enabling technologies are at Technical Readiness Level-6. Earned Value Management is being applied to all major contracts consistent with Agency guidance. Schedules are baselined and the project critical path is understood/managed. Budget with reserves established. Liens and threats system in use. Formal Configuration Management (CM) processes are in place. Project-level schedules are maintained within the CM system. Formal Risk Management processes are in place. Requirements are stable and flowed down. Project metrics are established and tracked monthly: a) Includes technical as well as cost and schedule metrics. b) Changes as well as trends are reported each month.

Sabelhaus, Phil↗

NASA NTRS2008

James Webb Space Telescope (JWST) Project Status for the AIAA Working Group on Space Simulation

This brief presentation discusses developments in the design of the James Webb Space Telescope (JWST). The JWST master schedule is provided and its system architecture is described. Instruments include the Near Infrared Camaera, Near Infrared Spectrograph, Mid-Infrared Instrument, and the Fine Guidance Sensor. Compared to other telescopes the JWST has a 2.7 longer wavelength than the Hubble Telescope (HST), 38 times better sensitivity at K band that the HST NICMOS, and 8-24 times better angular resolution than the Spitzer Telescope. among other features. Engineering or verification models for all telescope instruments are being assembled and tested in the current year. Currently, good progress continues to be made on critical path items and the JWST is on track for a June 2013 launch.

Sabelhaus, Phil↗

NASA NTRS2008

The Realities of Managing Complex Space Missions like the James Webb Space Telescope

An overview of the James Webb Space Telescope (JWST) project and its status are presented. The JWST is a deployable infrared telescope with a 6.5 meter diameter segmented, adjustable primary mirror. It has a cryogenic temperature telescope and instruments suited for infrared performance. It will be launched in 2013 on an European Space Agency-supplied Ariane 5 rocket 20 Sun-Earth L2 for a 5-year mission. Compared to other telescopes the JWST: has a 2.7 time longer diameter and 2.7 time longer wavelength capability than the Hubble Space Telescope (HST), 38 times increased sensitivity at K band and 8 times increased sensitivity at H band than the HST NICMOS; and, 8-24 times better angular resolution than the Spitzer. An instrument overview and integration and test flow overview are provided. The JWST project management approach, including organizational chart, program phases, technology status, and project critical path summary, are included. Additionally, project management tools and guidelines are are outlined.

Sabelhaus, Phil↗

NASA NTRS2007

Investigation of the NOAA N' S Search and Rescue Antenna Inadvertent Deployment: Type C Mishap

The NOAA N' Search and Rescue Antenna (SRA) inadvertently deployed during a spacecraft rotation on April 14,2007. This rotation was part of a normal operation to configure the spacecraft for additional antenna and the solar array boom deployments. This procedure (red flag written) had been modified to look for a lost metal washer and a thermal blanket button. The modification to the procedure was reviewed and approved by the Lockheed Martin Missiles and Space (LMMS) Material Review Board (MRB) per standard procedures. The flag to the procedure introduced a counter clockwise rotation before the normal clockwise rotation. The antenna was temporally stowed and held in place via lacing cord. The lacing cord broke and allowed the SRA to inadvertently deploy during the clockwise rotation. The SRA broke through a hard stop bracket and damaged an instrument optical sensor radiator panel. The satellite damage appears to be minimal and there were no injuries to personnel. The damage to the Advanced Microwave Sounding Unit (AMSU)-A1 instrument has not been fully assessed. Based on mishap site visits, interviews and data analysis, the Mishap Investigation Team (MIT) identified the underlying causes of the mishap. Event and causal factor tree diagrams were developed, resulting in the identification of the proximate (or direct) cause and root causes of the mishap.

Sabelhaus, Phil↗

NASA NTRS2002

Continuous Risk Management

Risk identification is an ongoing activity that takes place during the routine project work flow. Project activities such as programmatic and technical meetings, telecons, reviews, and other forms of communication often bring to light project risks. When this occurs, we record and analyze the risk on a Risk Information Sheet. This process helps the project team identify and cope with project risks throughout the life of the project.

Sabelhaus, Phil↗

NASA NTRS1998

The Recovery of TOMS-EP

On December 13th 1998, the Total Ozone Mapping Spectrometer - Earth Probe (TOMS-EP) spacecraft experienced a Single Event Upset which caused the system to reconfigure and enter a Safe Mode. This incident occurred two and a half years after the launch of the spacecraft which was designed for a two year life. A combination of factors, including changes in component behavior due to age and extended use, very unfortunate initial conditions and the safe mode processing logic prevented the spacecraft from entering its nominal long term storage mode. The spacecraft remained in a high fuel consumption mode designed for temporary use. By the time the onboard fuel was exhausted, the spacecraft was Sun pointing in a high rate flat spin. Although the uncontrolled spacecraft was initially in a power and thermal safe orientation, it would not stay in this state indefinitely due to a slow precession of its momentum vector. A recovery team was immediately assembled to determine if there was time to develop a method of despinning the vehicle and return it to normal science data collection. A three stage plan was developed that used the onboard magnetic torque rods as actuators. The first stage was designed to reduce the high spin rate to within the linear range of the gyros. The second stage transitioned the spacecraft from sun pointing to orbit reference pointing. The final stage returned the spacecraft to normal science operation. The entire recovery scenario was simulated with a wide range of initial conditions to establish the expected behavior. The recovery sequence was started on December 28th 1998 and completed by December 31st. TOMS-EP was successfully returned to science operations by the beginning of 1999. This paper describes the TOMS-EP Safe Mode design and the factors which led to the spacecraft anomaly and loss of fuel. The recovery and simulation efforts are described. Flight data are presented which show the performance of the spacecraft during its return to science. Finally, lessons learned are presented.

Robertson, Brent↗