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OFJ97 Field Journal from Ed Hirst - 2/14/97

Mission planning on Galileo, now that the spacecraft is deep within its orbital tour, has taken on a different flavor. In part, I am still involved in prime mission activities but this part is more geared toward supporting outreach activities and creating summaries of Galileo's activity during each encounter.

For example, I put together "Today on Galileo" and "This Week on Galileo," summaries of what the spacecraft is doing. These summaries go out all over the internet. I can't claim that I am the sole writer of everything you see on those features of the Galileo web page. I borrow many ideas from many documents that describe Galileo's plans in more detail. And I have an excellent group of co-workers that reviews and suggests modifications to what I put together before it gets posted. It is truly the end result the work of many people, a true team effort.

It is quite fun to do, especially when you realize that the work you are doing is directly influencing how people view Galileo. We are presenting Galileo's achievements for the whole world to see! The most interesting part of this work, and most difficult, is being able to turn some highly technical mumbo-jumbo description into words that everyone can understand. When we do that, we have done our jobs well.

The other part of my job is helping to plan for the Galileo Europa Mission, the follow-on to the Galileo mission (which is scheduled to end in December of 1997). GEM, as we call the Galileo Europa Mission, will run for two years. All of its flybys will be of Europa, with a possible two flybys of Io at the very end. We are still waiting to find out if NASA will give us the final okay for GEM.

I am getting insight into an entirely different aspect of mission planning, namely, the trajectory and mission design. When I started working, on Galileo the spacecraft was already on its way to Jupiter. The orbital tour--Galileo's exact itinerary giving the distances and dates of the different satellite flybys-- had already been picked. Since the Galileo Europa Mission is essentially a new mission, a new orbital tour must be selected and the Project Science Group--the group of scientists who decide which science observations to make--must decide on a whole new set of observations and experiments.

At the same time, the tour designers and mission designers (that's me) begin to worry about what options are available for the Project Science Group to examine. This involves everything from available trajectories to spacecraft capabilities and resources (how much propellant do we have? how much radiation can we absorb before things start breaking down?) down to Deep Space Network antenna time (are there other spacecraft like Cassini or Mars Surveyer that will need DSN antenna time when we need it?). All of these areas (and many others) must be considered in designing a new mission.

One of the places these ideas are captured is in a document called a Mission Plan. And it is my job to put together the Galileo Europa Mission Mission Plan (it sounds funny, but both "Mission"s are supposed to be there). But much like the outreach and summary work that I do, I am only one of many contributors of the information that is placed in that document. Again, it is a team effort and it is part of my responsibility to make sure that all of the pieces fit together in a coherent manner.



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