Trajectory planning


The Voyager missions were able to reach the outer planets because they used planet-sized gravity engines. The rocket that nudged them out of Earth’s gravity was a fraction of their power.

The only fuel these gravitational engines required was the initial angular momentum of the solar system left over from when it formed, so it was free and ready to use — Voyagers didn’t even have to bring it with them.

However the engines only work literally when the planets align — a Grand Tour of the solar system’s gas giants was possible only in 1977 and technology available to do it was only available for 1977.

I like the idea of learning via analogy, so, what can we use personally from the alignment of the planets and the Voyager missions?

It is rare to find and realize a preplanned, multistage trajectory of success
The more complex and amazing, the less likely. For the complex interactions that determine your personal life trajectory, these are rare and take much planning. Don’t expect them but never discount that planning ahead can lead to great things.

A Grand Idea can attract Grand Efforts
It takes many people working together to realize a single trajectory. This applies to spacecraft and personal success. Doing it alone is not realistic or best use of reality. The realization that the Grand Tour trajectory even existed was that of one graduate student, and 11,000 person years of effort were ultimately invested in building Voyagers and seeing them through the Tour. In a way the trajectory of serendipity and effort was as grand and unique as that defined by the solar system’s alignment.

Take advantage of the gravity wells and momentum in your environment
The real boost in your success comes not from your own engines but by heading where the opportunity is — follow the attractive forces and gain momentum from other’s momentum. While you are there, learn as much as you can.

Stick to something
Voyager missions are in their 40th year. The Grand Tour is their reason for existence, with long intervals of silence and steady preparation, grand moments of excitement and discovery — a story of stories

Redundancy works
Voyagers were effectively many spacecraft coexisting in the same hull, ready to take over for one another, and in many cases this saved the mission. The math is this — with two redundant systems of 10% failure probability each, the total system can be 10 time more reliable than without redundancy. Have a backup plan if failure is not an option.

Stay flexible
Voyagers were the first spacecraft with upgradable operating software. New tricks like data compression, workarounds for hardware failures were all used to rescue the mission from the unexpected. Stay flexible and open minded and grow beyond what you are now.

Have an audience
If Voyager had simply stored all its images and data on its internal tape, it would have been a failure. The goal was to learn and discover and share. An audience for efforts justify the effort and focus it — it keeps you coming back to the task when other motivations have faded.

Don’t overpromise, when you can overachieve
Voyagers were advertised as Jupiter-Saturn missions with an option for Uranus and Neptune encounters. Ever since then, JPL and other spacecraft mission designers have carefully divided efforts between what is the Mission and what is the Bonus. The mission is what you promise, the Bonus is what you strive for.

What you are doing can inspire as much as where you are going
The gold-anodized phonograph assembled by Drake, the Sagans and others and attached to the Voyagers contained examples of the best of humanity — photos, music, and greetings. It is one of the most well remembered outcomes of the mission, and was achieved before launch, and has a near-zero chance of mission success. What it did was show us how we would introduce ourselves as Human. The takeaway is that your efforts are really yours — other people might be capable of the same thing or greater, but why you did something is purely personal and what matters most.

More reading and resources

Book: The Interstellar Age by Jim Bell

PBS Documentary: The Farthest

JPL site: Voyager: The Interstellar Mission

BBC Podcast: Space 1977



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