Fengchuan Liu

Development of the Wide-field Infrared Survey Explorer (WISE) mission

WISE is a NASA MIDEX mission to survey the entire sky in four bands from 3 to 25 microns with sensitivity about 500 times greater than the IRAS survey. WISE will find the most luminous galaxies in the universe, find the closest stars to the Sun, and detect most of the main belt asteroids larger than 3 km. WISE launch is scheduled in November, 2009 on a Delta 7320-10 to a 525 km Sun-synchronous polar orbit. This paper gives an overview of WISE including development status and management approach. WISE flight system design is single string with selected redundancy and graceful degradation. Wherever possible, design heritage from prior missions is pursued and properly reviewed to reduce development time and cost. Further risk reduction is achieved since the WISE spacecraft has no deployable mechanisms and no propulsion. Nonetheless, a complex space mission with a sophisticated cryogenic IR telescope such as WISE demands a partnership of multiple organizations in government research, academia, and industry. With a cost cap and relatively short development schedule, it is essential for all WISE partners to work seamlessly together. This is accomplished by a single management team representing all key partners and disciplines in science, systems engineering, mission assurance, project and contract management. WISE uses a variety of management tools including frequent team interaction, schedule, milestone and critical path analysis, risk analysis, reliability analysis, earned value analysis, configuration management, and management of schedule and budget reserves. After a successful mission critical design review in June, 2007, WISE has completed building most of the flight hardware, and started integration and test within payload and spacecraft.

Using the ISS as a Testbed to Prepare for the Next Generation of Space-Based Telescopes

The infrastructure available on the ISS provides a unique opportunity to develop the technologies necessary to assemble large space telescopes. Assembling telescopes in space is a game-changing approach to space astronomy. Using the ISS as a testbed enables a concentration of resources on reducing the technical risks associated with integrating the technologies, such as laser metrology and wavefront sensing and control (WFS&C), with the robotic assembly of major components including very light-weight primary and secondary mirrors and the alignment of the optical elements to a diffraction-limited optical system in space. The capability to assemble the optical system and remove and replace components via the existing ISS robotic systems such as the Special Purpose Dexterous Manipulator (SPDM), or by the ISS Flight Crew, allows for future experimentation as well as repair if necessary. In 2015, first light will be obtained by the Optical Testbed and Integration on ISS eXperiment (OpTIIX), a small 1.5-meter optical telescope assembled on the ISS. The primary objectives of OpTIIX include demonstrating telescope assembly technologies and end-to-end optical system technologies that will advance future large optical telescopes.

The WISE science payload: management lessons learned

The Wide Field Infrared Survey Explorer is a NASA Medium Class Explorer mission which launched in December, 2009 to perform an all-sky survey in four infrared wavelength bands. The science payload is a cryogenically cooled infrared telescope with four 1024x1024 infrared focal plane arrays covering the wavelength range from 2.6 to 26 μm. The survey has been highly successful, with millions of images collected, and nearly daily discoveries of previously unknown astronomical objects. The WISE science payload was designed, built, and characterized by the Space Dynamics Laboratory at Utah State University. This paper provides a brief overview of the WISE science payload and its on-orbit performance and describes lessons learned from managing the design, fabrication, testing, and operation of a state-of-the-art electro-optical payload.

A payload-centric integration and test approach on the Wide-field Infrared Survey Explorer Mission

NASAs Wide-field Infrared Survey Explorer (WISE) mission was successfully launched on December 14, 2009. All spacecraft subsystems and the single instrument consisting of four imaging bands from 3.4 to 22 microns, a 40 cm afocal telescope, reimaging optics, and a two-stage solid hydrogen cryostat have performed nominally on orbit, enabling the trouble-free survey of the entire infrared sky. Among the many factors that contributed to the WISE post-launch success is the thorough pre-launch system integration and test (I&T) approach tailored to the cryogenic payload. The simple and straightforward interfaces between the spacecraft and the payload allowed the payload to be fully tested prior to integration with the spacecraft. A payload high-fidelity thermal, mass and dynamic simulator allowed the spacecraft I&T to proceed independently through the system-level thermal vacuum test and random vibration test. A payload electrical simulator, a high-rate data processor and a science data ingest processor enabled very early end-to-end data flow and radio-frequency testing using engineering model payload electronics and spacecraft avionics, which allowed engineers to identify and fix developmental issues prior to building flight electronics. This paper describes in detail the WISE I&T approach, its benefits, challenges encountered and lessons learned.

The WISE satellite development: managing the risks and the opportunities

NASAs Wide-field Infrared Survey Explorer (WISE) MIDEX mission is surveying the entire sky in four infrared bands from 3.4 to 22 micrometers. The WISE instrument consists of a 40 cm telescope, a solid hydrogen cryostat, a scan mirror mechanism, and four 1K x1K infrared detectors. The WISE spacecraft bus provides communication, data handling, and avionics including instrument pointing. A Delta 7920 successfully launched WISE into a Sun-synchronous polar orbit on December 14, 2009. WISE was competitively selected by NASA as a Medium cost Explorer mission (MIDEX) in 2002. MIDEX missions are led by the Principal Investigator who delegates day-to-day management to the Project Manager. Given the tight cost cap and relatively short development schedule, NASA chose to extend the development period one year with an option to cancel the mission if certain criteria were not met. To meet this and other challenges, the WISE management team had to learn to work seamlessly across institutional lines and to recognize risks and opportunities in order to develop the flight hardware within the project resources. In spite of significant technical issues, the WISE satellite was delivered on budget and on schedule. This paper describes our management approach and risk posture, technical issues, and critical decisions made.