Back from the Cassini Launch

by Ron Baskett, LUNAR #188

I think that most of us model rocket hobbiests have been inspired by one or another aspect of the space program from our younger days. Those of us in our forties were kids during the race to the moon set off by that little beeping basketball circling the earth. I chose to begin my career in meteorology working with satellite data at the Johnson Space Center, but just missed the heyday of the space program. We'd already brought back enough rocks, and jumped, roved and golfed at 1/8th earth's gravity. NASA canceled the last 3 moon shots and on my birthday in July, 1975, I regretfully watched the Apollo capsule connect with Suyoz, the last and seemingly anti-climatic use of the big Saturn.

It would be another 20 years before I had the fortune to work again with the real rockets -- in the fall of 1995 assisting the Air Force at Vandenberg with the simulation of the toxicity of the hydrochloric acid exhaust cloud of the last few Peacekeeper launches. A night launch always adds extra excitement, and I will always remember the healthy roar of the first real rocket launch I saw.

So two years ago when our emergency response program at Lawrence Livermore National Laboratory was asked to support the Cassini launch, I again became thrilled at the idea of being involved in the real thing. Since the US Department of Energy built the Radioisotope Thermoelectric Generators (RTGs), the agency also owned the issue of their safety. That issue became headlines early this fall as several groups organized emotional, political, and eventually, as a last ditch effort, legal battles against using nuclear-powered spacecraft. I listened intently to legitimate arguments waged on those three levels, but the opposition wasn't even in the same ball game when it came to the technological level. After all they hardly had the resources to smash hundreds of iridium-encased marshmallow-sized ceramic cubes into concrete and check how much inhalable dust was produced.

The engineers who designed and build the Titan rocket, the Cassini spacecraft, and the RTGs had done their homework. They carefully modeled an enormously complex set of high energy failure modes each of which could produce a wide number of effects. Having forecasted the weather, I sympathize with these engineers -- credibility is difficult to establish for low probability events. But I also trusted their calculations and agreed with Carl Sagan who during the Galileo launch publicly stated that the low level risk of a potentially extremely minor exposure was acceptable to him. Unfortunately he was not with us this time to again express his trust in the Cassini engineers during the last use of nuclear power for a major interplanetary mission this millennium.

From the first planning meeting two years ago, our group, the Atmospheric Release Advisory Capability (ARAC), geared up our system in preparation to support the Cassini launch. We linked our computers with NASA's extensive meteorological network at the Cape and for months before launch we intently practiced modeling the very unlikely several times a week. When our field team of four arrived at the Cape, we found that we were only one small component of the major preparedness effort for the short 33 seconds during which the risk to humans was finite.

The cancellation during the first window on October 13 seemed as though a successful launch was not just like threading a needle, but like threading a series of moving needles. Although winds remained onshore during the night of the second window on October 15th, all criteria remained green during the countdown. At L-5 minutes all mandatory criteria were reviewed including ours to which we replied, "ARAC-go." We all held our breath and sighed a collective relief as the Titan's solids lit up the sky and roared into destiny. There's nothing like a night launch and although not as big as the Saturn or the Shuttle, we were not disappointed by this near perfect performance.

My trip was made more enjoyable the day before launch when I was fortunate to connect up with the former head of the Apollo Extravehicular Manned Unit. We played a couple sets of tennis at the Cape Canaveral city courts, and afterwards Ed bought me a beer at the Tiki Hut at the port. It was fun to hear him reminisce about several astronauts, such as how Conrad instinctively shut down and repowered his spacecraft moments after liftoff when they were hit by lightning, and how everyone knew exactly what they had to do during Apollo 13. I had just gone on the Space Center tour which included a visit to a newly restored Saturn V. Walking the length of the V brought back childhood memories of watching launches on TV. I wonder what the Safety Analysis Reports said about the RTGs on each of the Apollo missions -- back when the stakes were higher with astronauts on board. They certainly placed a great deal of trust in the engineers then, and I know that we can continue to trust our space engineers in the future.

Information date: November 25, 1997 lk