December 2007

From Dave McComas, IBEX Principal Investigator

Dave McComas
Spin Balance Test Video
Spin Balance Test Video.     Click to play video. Credit: Orbital Sciences Corporation

Throughout November the IBEX team worked to complete spacecraft integration and begin final testing. One of the first tests - spin balance - is shown in the brief video clip. In this test the full spacecraft is spun at rates up to 70 RPM! We spun the spacecraft both in air and in a Helium tent (shown in the video) to simulate the vacuum environment of space (Helium is only 14% as dense as air). Once the initial spinning was done we added little balance masses, very much like the auto shop does when they balance your car tires.

Other critical activities included testing of the flight software. This software provides the "brains" for operating the spacecraft on orbit and covers not just normal operations, but also things like automatic safing in case anything goes wrong during the roughly week-long intervals when the spacecraft will be operating autonomously. This month I'm delighted to introduce Erin Walter from Orbital Sciences. As the IBEX flight software lead, she is responsible for making sure that all of the software works perfectly. Erin has been doing a great job of owning the critical flight software for us. 


Meet the IBEX Team: Erin Walter

By Christine Minerva, Adler Planetarium Educator

Erin Walter, IBEX Flight Software Lead

Erin Walter, IBEX Flight Software Lead

If passing a computer class had not been a college graduation requirement, Erin Walter might never have worked on a NASA mission. 

Originally a business major at the University of Michigan, Erin enrolled in a computer class because it was mandatory. She soon found the computer curriculum so absorbing that she ignored assignments in her business classes, like accounting. "I had an exam in my accounting class the next day, and a computer class project that was due in about three months. The night before the accounting exam, I stayed up to finish my computer project instead of studying for the exam!" Erin said. It was her first indication that computer programming was a good fit for her interests. 

After completing the computer class, Erin switched her major to computer science. The following year, she became one of the few University of Michigan undergraduates to teach other undergraduates as an instructor for the same computer class. She continues to further her education, and is completing a master's degree in software engineering from the University of Michigan, and is in the process of earning another advanced degree in systems engineering at George Washington University. 

As a child, Erin had no idea that spacecraft software engineering was in her future. In fact, she aspired to be a lawyer. Born in San Jose, California, Erin moved to the Ann Arbor, Michigan area with her family when she was two years old. She attended Walled Lake Western High School, graduating a semester early before going on to the University of Michigan for college. 

She is grateful that her alma mater required her to take classes outside her major. "I think when colleges require students to take classes outside of their majors it provides a tremendous opportunity for students to become interested in areas they never would have imagined or maybe even find their career, like I did. Taking a computer class made me realize that I was going to be happier in another field. I chose to major in business because I didn't know what I wanted, and I thought I could get a job with that degree. But I was never really all that interested in business. Once I took a computer class, I was interested in the logical nature of computers. Computer science made sense to me - it was very natural for me to understand how things worked together to make a computer work," she said.

Erin went on to a varied career in computer software engineering. After college, she worked for a private software company before taking a position to create software for an instrument on NASA's Cassini mission, now orbiting Saturn. Her position there included ground software, flight software, operations and running the lab. Since then, she has moved on to greater challenges as the flight software lead for the MicroStar product line at Orbital Sciences Corporation. The MicroStar is the type of spacecraft "bus", to which the science instruments are attached. "I develop the flight software that essentially runs the MicroStar spacecraft," she said. "The spaceflight software is kind of like if you had to build artificial intelligence to drive a car and manage the hardware aspects as well. The hardware is like the car and you automate the rest, like the steering, the car battery, and all the stuff someone does when they drive a car, through the software." To ensure that everything works correctly, Erin programs the software to correct for problems that may occur. "The software detects flaws. For instance, if we detect that the battery is too low, the software may maneuver the IBEX spacecraft to point towards the Sun to recharge, and it may shut down things that are unnecessary in order to conserve energy," she said. 

Her education and software experience prepared her for the work she does now. "I was well prepared for the technical aspects of my job by my education. My prior job experience prepared me for my management role, time management skills, spacecraft knowledge, people skills, etc." In the future, she hopes to take what she has learned and apply it to the management of an entire project. 

Erin leads a diverse team of men and women from around the world who write the software that controls IBEX. "They are an incredible good group of people and it really is my privilege to have them on my team" she said. "They are very knowledgeable and experienced on this type of spacecraft," she said.

After she and her team write the software, Erin's job transitions to testing the software and eventually to assisting in operating the spacecraft. In the past month, Erin has been focusing on assisting in testing the IBEX spacecraft to make sure the software will work correctly in space. This has involved creating test procedures and troubleshooting. "During integrating and testing of a spacecraft, certain things might not work the way [the scientists and engineers] want them to. They'll change a requirement or find a bug, so I go ahead and make those changes to the software and redeliver it to the spacecraft. Then, they rerun those tests to make sure that the change they said they wanted works the way they want it to," she said. 

When the software is finalized, Erin and her team co-author an operating manual for the spacecraft, and then she is "on call" to help operate IBEX. "As the mission goes on, myself and my team typically become the ones who knows how many things work and how to command the spacecraft to do certain things, so [the scientists] call me up and ask, 'How do I make the spacecraft do x, y, or z?' and I tell them how," Erin said. 

She loves the problem-solving aspects of her job. "The best part of my job is helping design the requirements and functionality of the spacecraft based on the requirements, and finding the most optimal solution," she said.

Although software engineering keeps her busy, Erin still finds time to pursue a range of hobbies. "I enjoy pottery, art, going to plays and shows, watching football, reading, scuba diving and always seeking out new experiences," Erin said.