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Today marks the Autumnal Equinox, when the Sun crosses directly over the Earth’s equator, heading south. The equinox marks the official astronomical start of fall in the Northern Hemisphere and spring in the Southern Hemisphere. It occurs tonight at 8:05 PM EDT. Days continue to grow shorter and the sun appears lower in the sky.
I wrote an article about the importance of four important astronomical days – the solstices and equinoxes – in my career as a spacecraft thermal engineer. That training has influenced my approach to personal financial planning. Basically, you design a plan and test it against worst case conditions. If you have a satisfactory margin of safety in the worst-case environments and conditions, you have a high probability of success. I still think along those lines, and will monitor our plan as environments and conditions change.
The autumnal equinox is about harvesting the crops we’ve sewn through the spring and summer. It’s about accumulating enough to survive the cold and dark of late fall and winter. It occurs to me that is a pretty good metaphor for retirement. Enjoy
Hey Rick, dare I mention that my retirement worst case margin of safety was replacement income not at 70% 80% or 90% but…% of working base salary. 🤑 and working until it was achieved.
Rick do you think the thermal spacecraft engineer that designed the Voyager I spacecraft, currently located more than 15.9 billion miles, took into account the temperatures that far from earth.
As a fun project please get out your slide rule to perform the calculations and let us know what the rough low temperatures are that far away. 😉
David,
The coldest space temperature is Absolute Zero (-458F, -272C). That far from the sun it is a pretty conservative estimate of the thermal environment that Voyager 1 is exposed to. Satellites in earth orbit are exposed to that temperature on the sides facing away from the sun and from the Earth. So the worst case cold environment is established by physics.
Voyager 1 has one big advantage – 3 RadioIsotope Thermoelectric Generator (RTG) Power source that always gives off some heat. They were designed and built by GE in Valley Forge, PA by some of my early colleagues. The 3 RTGs currently generate about 220W of electrical power ; about 50% of its launch capacity. That is a couple of lightbulbs of electric power. But the 3 RTGs Plutonium 93 fuel still puts out a combined 4900 W of thermal power (heat) which are used to keep the vehicle warm.
It is standard procedure for spacecraft operational flight team engineers to monitor critical spacecraft characteristics, analyze trends, and forecast future performance and issues, once launched.I was involved in the supporting of flight operations for a number of spacecraft. some decades after their original design life was exceeded. The Voyager 1 Flight team has updated the thermal models over the decades to monitor flight temperatures and available power. The biggest concern is freezing the onboard propellant – hydrazine. They have 5 decades of experience flying the vehicle and are doing a great job. According to Google, the original thermal engineer at NASA’s JPL is 90 years old and retired in Palm Springs.
Your question fits with the metaphor. A long-lived retiree needs to monitor and adjust the financial plan as conditions evolve and longevity happens.
I was in that temperature once in upstate NY