Critical Burn

Apollo 8 TEI Pad — Page 1

It’s hard to go through Christmas without seeing at least one reference to Apollo 8, the mission that first flew humans to the Moon. For those who don’t remember the timing, Borman, Lovell, and Anders read from Genesis as they looped around the moon and shared earthrise with humanity for the very first time. It was a milestone mission – and it was an incredibly gutsy call, to head out to a distance of a quarter million miles in a spacecraft that had only flown once, and with no redundant engine to bring them home if the single rocket motor on the Service Module (SM) had developed a problem. Just how gutsy was illustrated when Apollo 13 had its problem the following year, and they had to use the LM to get home. Apollo 8 had no LM.

This was one of those moments when you realize you’ve dodged a bullet after it has already gone by. At the time, you didn’t realize the danger – only in retrospect do you realize that you were hanging it out there. The problem is that if you continually dodge bullets, you eventually come to think that you are untouchable – or you gradually become gun shy. Threading the needle between those states of mind is where Flight Directors live.

Regardless- I like to be reminded of Apollo 8 at Christmas time, and this year I received an email from Chuck Dietrich, one of the legendary veterans of the Trench back in the Apollo days. Chuck is also an experimental aircraft builder, and has written for our magazine in the past – and has sent me an article or two for the future. The other day, Chuck sent me a scan of a very important piece of paper that he has in his collection – the Trans-Earth Insertion (TEI) PAD from Apollo 8. A Burn PAD is a form which the FDO (Flight Dynamics Officer) fills in all the data the crew needs to execute a maneuver – the times, angles, burn parameters, targets, etc. – and pass that on to the CAPCOM, who reads it up to the crew. The crew then reads it back, and the CAPCOM (and the Trench guys) check that the crew got everything right. The CAPCOM often checks each item off as it is verified.

TEI was important because it was the burn that sent the crew out of Lunar orbit and on their way back to Earth. Get it wrong, and they weren’t coming home. And this was the first time one had ever been performed.  And….it was performed on the back side of the moon, out of contact with Earth. On Apollo 8, after the burn, when they came back around into radio contact, Jim Lovell said those famous words “Houston Apollo 8 – please be informed that there is a Santa Claus!” The burn had gone off perfectly, and they were coasting downhill on their way home.

It was ironic, then, that Lovell was the commander of Apollo 13 when they lost their capability to use the SM engine, and had to rely on that LM. They had dodged the bullet on his first trip to the moon, without really realizing that they were hanging it out there. Never again would we send humans into space without several methods of burning to bring them home. So, did that make us feel immortal…or was it a sign of becoming gun shy?

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