Old School

Deirdre and I went on a sort of roadtrip stay-cation over Labor Day weekend. We drove east to spend a few days with my parents. My father is about to turn 80 and he has slowed down a little the past few years, and I know he appreciates it when we can make it back to spend the weekend with him and my mother. We left for my parent's house a little before 3PM and I was caught up in an 80 mile per hour parking lot. There was a lot of traffic on I-96, but it was moving along. We arrived at my parent's house in a little less than two and a half hours, which was darn near record time.

The weather for our visit could not have been better. Warm, cloudless and sunny days, with cool, clear nights. My plan was to make dinner each night for my parents (and Deirdre, too!) and work on any chores my father might have around the house. My father marinated a flank steak for Friday night's meal, and we made some rice, steamed green beans and a tossed greens salad. My father enjoyed the company as well as having somebody else make him a meal. We picked up the ingredients for this meal from the Village Market. The Village Market has been in business since 1939, serving the best in meats, seafood and groceries. It is an old fashioned butcher shop, something that has all but disappeared with all the Wal-Marts and chain grocery stores.

The subject of this post, old school, is about Deirdre and going back to the town where I was born (Detroit) and raised (Grosse Pointe). I have not lived in either place in almost three decades, and in the course of all of those years, there are a few places which seem to never change. Mack Avenue has had a few changes along the margins, but certain places have changed little since I left. We had lunch at the Irish Coffee on Saturday. It menus has been the same since it opened four decades ago. There are darn few watering holes in my home town, and the IC is one of the best known. Sure, you can go to Little Tony's Lounge in the Woods, or maybe Telly's Bar & Grill on the other side of 8 Mile. Each has its own feel, but when I walk into any of the aforementioned places it is as if I had never left.

We went to an even older school place for lunch on Sunday: Sinbad's. Sinbad's is celebrating its 60th anniversary this year. If you walked into Sinbad's tomorrow, it would look very similar to how it looked 30 or 40 years ago. The long wooden bar was refurbished a few years ago to its look and feel from 30 years ago: polished mahogany. Ask almost anyone who was raised on the east side of Detroit and most of them have been to, if not heard of Sinbad's. I had a cup of their chili, the recipe for it has not changed, ever, as far as I know, a burger and Stroh's. I also saw something I have not seen in years: a cigarette machine. Hopefully, Michigan will soon join the ranks of the majority of states and ban smoking in most public places, but until then, there will be cigarette machines at Sinbad's. If you have a spare $7.50, you, too, can buy a pack of Marlboro cigarettes.

Yep, it was an old school weekend.

Gravity and Celestial Mechanics

I work for GE Aviation. We make avionics for civilian and military aircraft and I like to think that we are the best aviation company on the planet. I am the Reliability Group Manager, which means I supervise the work of seven reliability engineers. These talented folks are electrical engineers by education and they are darn good in what they do. My people look at electronic schematics, circuits and analyze the reliability of these systems. They are the best at what they do.

In the course of my career with GE, my coworkers have learned that I am not an electrical engineer. Rather, I was trained in chemistry and mathematics. In order to understand the chemistry I studied, I had to take a lot of physics classes. They also understand that I served as a Navigator of a destroyer, so I have an understanding of celestial navigation and celestial mechanics. Also, these aforementioned electrical engineers are very focused on, well, electrical engineering. Few of them took classes outside of the mathematics needed to take "double E" courses and they certainly did not take courses in celestial mechanics. This is where I come in...

One day at lunch, my friend Greg asked me, "Paul, do you know anything about how gravity works? Specifically, do you understand why a planet is used, sometimes, to increase the speed of a deep space probe?"

I answered, "Why yes, yes I do." I explained to Greg that the reason why gravity is sometimes used to increase the speed of a deep space probe because there is essentially a "well" that is created by the mass of a planet in space-time. NASA has used planets to increase the speed of deep space probe, and this is known as a gravity assist.

A gravity assist or slingshot maneuver around a planet changes a spacecraft's velocity relative to the star around which the planet circles, even though it preserves the spacecraft's speed relative to the planet—as it must according to the law of conservation of energy. To a first approximation, from a large distance, the spacecraft appears to have bounced off the planet.

Realistic portrayals of encounters in space require the consideration of two dimensions. In that case the same principles apply, only adding the planet's velocity requires vector addition, as shown below.

Thus, to a stationary observer measuring the velocity of the spacecraft, its velocity increases relative to the observer. NASA has used this on the Mariner, Voyager, MESSENGER and Cassini missions. I have certainly learned a lot from these electrical engineers, but is is refreshing to share a bit of the knowledge with some really bright people.