David F. Everett

The OSIRIS-REx asteroid sample return mission

In September of 2016, the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security, Regolith EXplorer) spacecraft will depart for asteroid (101955) Bennu, and when it does, humanity will turn an important corner in the exploration of the Solar System. After arriving at the asteroid in the Fall of 2018, it will undertake a program of observations designed to select a site suitable for retrieving a sample that will be returned to the Earth in 2023. The third mission in NASAs New Frontiers program, OSIRIS-REx will obtain a minimum of 60 g of a primitive asteroids surface, the largest sample of extra-terrestrial material returned to the Earth since the end of the Apollo lunar missions (Figure 1). OSIRIS-REx will also return a separate sample of the fine-grained surface material that is <;1 mm in diameter.

Preparations for Global Precipitation Measurement (GPM) ground validation

The Global Precipitation Measurement (GPM) program is an international partnership led by the National Aeronautics and Space Administration (NASA) and the Japan Aerospace Exploration Agency (JAXA). GPM will improve climate, weather, and hydrometeorological forecasts through more frequent and more accurate measurement of precipitation across the globe. This paper describes the concept and the preparations for ground validation within the GPM program. Ground validation (GV) plays a critical role in the program by investigating and quantitatively assessing the errors within the satellite retrievals. These quantitative estimates of retrieval errors will assist the scientific community by bounding the errors within their research products. The two fundamental requirements of the GPM ground validation program are: (1) error characterization of the precipitation retrievals and (2) continual improvement of the satellite retrieval algorithms. These two driving requirements determine the measurements, instrumentation, and location for ground observations. This paper describes GV plans for estimating the systematic and random components of retrieval error and for characterizing the spatial and temporal structure of the error. This paper describes the GPM program for algorithm improvement in which error models are developed and experimentally explored to uncover the physical causes of errors within the retrievals. GPM will ensure that information gained through ground validation is applied to future improvements in the space-borne retrieval algorithms. This paper discusses the potential locations for validation measurement and research, the anticipated contributions of GPMs international partners, and the interaction of ground validation with other GPM program elements.

Plans for Global Precipitation Measurement ground validation

This paper introduces plans for ground validation (GV) for the Global Precipitation Measurement. At NASAs request, a Ground Validation Working Group, formed from the meteorological and hydrological communities, is recommending plans to guide the GV program. Ground validation efforts will commence as early as 2003 with the Spring 2003 Pilot Experiment and described herein. The Pilot Experiment is focused on mitigating engineering and scientific risk to the GPM program and, in particular, to the ground validation program.

OSIRIS-REx, returning the asteroid sample

This paper addresses the technical aspects of the sample return system for the upcoming Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) asteroid sample return mission. The overall mission design and current implementation are presented as an overview to establish a context for the technical description of the reentry and landing segment of the mission.

Designing to sample the unknown: Lessons from OSIRIS-REx project systems engineering

On September 8, 2016, the third NASA New Frontiers mission launched on an Atlas V 411. The Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) will rendezvous with asteroid Bennu in 2018, collect a sample in 2020, and return that sample to Earth in September 2023. The development team has overcome a number of challenges in order to design and build a system that will make contact with an unexplored, airless, low-gravity body. This paper will provide an overview of the mission, then focus in on the system-level challenges and some of the key system-level processes. Some of the lessons here are unique to the type of mission, like discussion of operating at a largely-unknown, low-gravity object. Other lessons, particularly from the build phase, have broad implications. The OSIRIS-REx risk management process was particularly effective in achieving an on-time and under-budget development effort. The systematic requirements management and verification and the system validation also helped identify numerous potential problems. The final assessment of the OSIRIS-REx performance will need to wait until the sample is returned in 2023, but this post-launch assessment will capture some of the key systems-engineering lessons from the development team.

Engineering a successful mission: Lessons from the Lunar Reconnaissance Orbiter

Schedule pressure is common in the commercial world, where late delivery of a product means delayed income and loss of profit.12 Research spacecraft developed by NASA, on the other hand, tend to be driven by the high cost of launch vehicles and the public scrutiny of failure—the primary driver is ensuring proper operation in space for a system that cannot be retrieved for repair. The Lunar Reconnaissance Orbiter (LRO) development faced both schedule pressure and high visibility. The team had to balance the strong push to meet a launch date against the need to ensure that this first mission for Exploration succeeded. This paper will provide an overview of the mission from concept through its first year of operation and explore some of the challenges the systems engineering team faced taking a mission from preliminary design review to pre-ship review in 3 years.

Validation and error characterization for the Global Precipitation Measurement

In this paper, we have dealt with the validation and error characterization for the Global Precipitation Measurement (GPM) research initiative. The GPM is a three-year on-orbit duration program with a five-year duration goal. The Core satellite launch is scheduled tentatively for Fall 2008. Presently, GPM is in formulation stage in which the team is developing concepts and requirements prior to design work. As a part of formulation, ground validation is developing its requirements with a top level schedule requirement of commencing GV operations two years prior to the Core satellite launch. The rationale is that GV will benefit from a two-year head start in preparation for the Core observations. The requirements for GV are being developed in collaboration with, and vetted by, the precipitation science community.