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Ocean Surface Topography from Space
"Instruments and individuals are the recipe for success." - A Q&A with Dr. Mohamed Abid, OSTM/Jason-2 Project System Engineer
September 01, 2005

Advanced Microwave Radiometer Team, Mohamed Abid (kneeling, third from left)
Image credit: NASA/JPL-Caltech

The Ocean Surface Topography Mission on the Jason-2 satellite (OSTM/Jason-2) is making steady progress toward a June 2008 launch. A suite of sophisticated instruments developed by a highly qualified team of engineers will enable the mission to extend the record of ocean surface topography measurements made by TOPEX/Poseidon and Jason-1. Success of the mission will depend not only on the instruments functioning properly but also on how well the individuals who make up the international partnership work together. Project system engineer Dr. Mohamed Abid offers his perspective on the excitement and the challenges associated with this ocean altimetry mission.

How long have you been involved with the OSTM/Jason-2 mission and in what roles?

Mohamed (far right) with student buoy project team members
Image credit: NASA/JPL-Caltech

I've been on the team for about 3 years. I began as the Payload System Engineer, and my responsibilities have steadily increased since then. I am presently the Project System Engineer and the Engineer Technical Authority for OSTM.

In parallel, I had the opportunity to share the excitement of the mission with future scientists and engineers. Last year, I mentored a group of students aged 9-17 in a project to construct and launch a buoy as part of an international oceanography education program. The project was rewarding for me as well as for the students.

What is a system engineer and what are your duties on OSTM/Jason-2

A system engineer is an individual that masters a set of technical and behavior functions. For example, on the technical side, my duty was to make sure that the instruments we design and build meet performance and interface requirements. This would guarantee a successful integration on the spacecraft, launch, and on-orbit operation. On the behavior side, it was important, for example, to establish and ensure a clear communication flow among not only the JPL instrument teams, but also with our international counterparts, CNES, the spacecraft contractor Alcatel Alenia Space, and Eumetsat.

As system engineer, what have been your biggest challenges with this mission?

OSTM is an international mission; therefore we've had some philosophical and technical approach differences among the partner agencies. From the NASA/JPL side, we also had to comply with U.S. laws and regulations regarding export and import of technical information. These factors have made it an interesting challenge to design, manage, and implement our project.

What is your own specific area of research and what do you find most technologically interesting about the OSTM/Jason-2 mission?

AMR instrument installed (background) Project System Engineer, Mohamed Abid (standing, second from left)
Image credit: NASA/JPL-Caltech

My research includes sensor development and mission architecture. For example, the main goal of OSTM is to continue the multi-decadal measurement of global sea surface height that began with the TOPEX/Poseidon mission in 1992. Sea surface height is measured using the Poseidon altimeter. However, to account for altimeter measurement errors that result from moisture in the atmosphere, ionospheric effects, or spacecraft position, a suite of additional instruments is used. On OSTM this suite includes the Advanced Microwave Radiometer (AMR), Global Positioning System Payload (GPSP), and Laser RetroReflector Array (LRA). The development of such sensors and methods for combining different instruments to get a coherent measurement is fascinating to me. I explore some of this in my textbook "Spacecraft Sensors" published by John Wiley & Sons.

Looking forward twenty years, what would be some key features of the next generation radar altimeter for measuring ocean surface topography?

Well, interferometry is a powerful technique that is used when high resolution measurement is needed. For example, radar interferometry would benefit ocean surface topography measurements tremendously. Some of the benefit in using this technique includes being better able to study mesoscale eddies, (eddies ranging in size from 1-100 km (.62 - 62 mi)) and the role of eddies in climate. Some initial development of this technology was done during the formation phase on OSTM, known then as the Wide Swath Ocean Altimeter (WSOA). However, it was decided to implement this type of instrument in the future and focus on the core mission on OSTM.

I am optimistic that, with the wealth of knowledge gained in the development of WSOA, such technology will be used to see the surface of the ocean in the near future.

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