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Planetary News: Cassini-Huygens (2004)

A Conversation With Charley Kohlhase

Charles Kohlhase has spent more than four decades at the Jet Propulsion Laboratory (JPL), working on such missions as Mariner, Viking, and as Mission Design Manager for Voyager as well as for the Cassini-Huygens mission to Saturn and Titan. He has also worked as a consultant on the Genesis, Kepler, and the Mars Exploration Program. Today, Kohlhase serves on The Planetary Society Advisory Council and works as an artist, specializing in combining the mediums of computer graphics and photography. Here, Charley talked with The Planetary Society about his other role on the Cassini-Huygens mission -- as public outreach coordinator, and creator of the DVD Signature Disc that is onboard Cassini and its way to the Ringed Planet.

Q: How did you end up in charge of the public outreach effort on Cassini --did you dream up this idea or did NASA/JPL come to you?

A: I had done public outreach efforts for years at JPL. I was always interested in making what we did at JPL exciting for the public and so I tended to prefer writing articles for popular magazines like Sky & Telescope and OMNI and venues like that over drab technical presentations. I was also part artist, so it was natural to want to combine the art, the science, and the education. Once I started that back in the 1960s, I was just sort of allowed to keep doing it and when Cassini-Huygens came along, I was asked to take that on as an additional duty, so I did.

Q: Why did you think it was important to include members of the public on missions like this?

A: Well, because at JPL we feel that it’s exciting, not only by the mission that’s being carried out, but when you work on a mission you feel a personal involvement. After all, you're going into work 50 hours a week on something you believe in. So if there’s a way to make the public feel a part of it, that's got to be a good thing. There are number of ways you can do that, but one of them has to do with letting them send a part of themselves on the journey.

Q: You did that by creating a signature disc. Tell us how that came about --

A: Well, the concept of signatures has been around for a long time. Pioneers used to carve their initials on stone and trees -- although I hate to see tree graffiti, because I’m an environmentalist -- but people like to leave part of themselves where they've been. And a signature is just as unique as a fingerprint, and back in the 1950s, even when JPL was conducting just rocket launches, engineers would often write their names with a grease pencil somewhere on either the skin of the vehicle or inside. Eventually, when we started launching the Mariner missions to Mars and Venus and, of course, Voyager on the Grand Tour, we got a little more sophisticated. We would have people sign their name and then these names would be etched onto an aluminum plate that was about 4 by 5 inches big, and the plates would be stored somewhere inside the spacecraft. If we really reduced the size of the signature, a little aluminum plate could hold about 900 signatures.

We flew six of those plates on each of the two Voyager spacecraft, which held about 5400 signatures. Galileo flew 11 plates like that, which was almost 10,000. Then in the 1980s, the development of the CD ROM came along, and that of course held a lot more information -- 650 megabytes. We realized that if you scan signatures and convert them to digital form you might be able to store a million signatures, rather than a few thousand. In other words, we could jump by almost 3 orders of magnitude. We could increase the number of signatures by about 1000 times.

So in 1995, with Cassini-Huygens, the project manager, Dick Spehalski, called me in and said, "Let's do this signature thing. What do you think about some other medium that will hold even more signatures?

I said, "I think it's a great idea; let's do it." So Spehalski basically said: "Charley make it so." I put out an announcement on our website inviting the world to send us their signatures on a postcard if they wanted to have them fly on this great journey to Saturn and Titan. The caveat of signing their names and mailing them in meant, for us anyway, that they would have to be a little more motivated than by simply typing their names in an email, for example.

By then, the DVD had been developed -- which initially stood for Digital Video Disc -- then eventually became Digital Versatile Disc because it was used to store more than just video data. Since the DVD would hold a lot more than a CD ROM, I decided to use one of those. So we started collecting signatures over a period of many months.

Having your own unique hand signature orbiting the ringed giant planet Saturn and orbiting for a long time just kind of makes you feel good and it makes people feel more a part of the mission. They're kind of out there with us, you know, and they will be with us wanting to make sure we go into orbit successfully the night of June 30th. They will be with us as we learn about Titan and all the other moons. It’s kind of like they're riding along with us. And they are. In fact, Cassini may have been among the last projects that just took the ‘John Henry’ right off a piece of paper. I know in Europe, they had a signature process for Huygens, but they had it automated in some digital way.

Q: What was the response to your invitation?

A: It was pretty much a flood in the beginning. We were getting at one point in time 35,000 signatures a week. In fact, we finally ended up getting 616,420 signatures from 81 different countries. Obviously, most came from the United States, but we also got a lot from Canada and Great Britain and Australia -- and many came from, if memory serves, from the bigger developed countries mostly in the northern hemisphere. But there were some countries from which we only received 1 signature -- such as Bermuda, El Salvador, Ghana, Qatar, Tanzania, and Zimbabwe.

Q: I presume, given the remarkable response, that there was quite a variety of signatures -

A: Yes, actually the enormous variety of signatures was really something --signatures came from people who were so old that their handwriting was scrawled across the postcard. We would get signatures from very young and very old. We had signatures I think from the age of 2 to maybe 100, and we had names from A to Z. We also would get signatures from entire schools. The school would decide that it was such an important thing to do that they would get everybody in the school to sign. We'd receive a big manila envelope and in there would be hundreds of signatures.

Q: Any recognizable signatures?

A: Oh yes, we had celebrities. Patrick Stewart [Star Trek: The Next Generation] sent his in. Chuck Norris sent his signature in. The entire crew from the movie First Contact sent theirs in. We even got a signature from Mary Cassini, who lived in Australia, and who was a distant descendant of Jean-Dominique Cassini, the astronomer after whom the mission was named. We also went back to the1600s to find signatures on letters written by Cassini and Christian Huygens.

Q: Now, I know that volunteers from the Planetary Society joined the effort -- would you expound on that?

A: Yes, I had this enormous stack of postcards and boxes of letters and things like that and had to do something with all of it. Thankfully, volunteers from The Planetary Society agreed to count and scan all these signatures. Since the DVD held more data than a CD ROM, it meant that they wouldn't have to spend huge amounts of time compressing the data. But, it was still a sizeable job. With their database, they could figure out how many were coming from the different countries and what signatures they might have gotten that were really unique. They spent many months doing that. One of the volunteers, Joe Oliver, logged 334 hours of unpaid time. That was truly amazing.

The Planetary Society volunteers did have a lot of fun with the project. Imagine getting mail from 81 different countries and the stamps were beautiful in many cases and so people would 'oooh' and 'ahhh' over some of the stamps and marvel at the different letters and things people would send in. With that process underway, every couple of weeks or so, I would get a tape and bring it back to JPL and store those scans in two different places on hard disc drives, so that if we lost the information in one place it wouldn't be lost in another. We protected it as well as we could. Finally, when it came time to get the DVD ready to be mounted on the side of the spacecraft, we had to obviously call an end to the collection process.

Q: And you, as I understand it, got to design the cover -- tell me about that.

A: Yes, as an artist, I had the happy opportunity to design the cover of the DVD, the disc itself. I decided to put the flags of 28 of the countries that represented 99.5% of the signatures around the outside. But I also wanted to put something on there that would be symbolic of the beauty and power of flight, as well as the signature process. I decided to use a wing feather from a golden eagle [Aquila chrysaetos], which is of course beautiful, reminiscent of both flight and of a quill pen. The golden eagle has a wide-ranging habitat throughout the Northern Hemisphere largely. Since this was going to be something done by people around the world I didn’t want to force a purely American symbol on them, so that’s why I chose the golden eagle over the bald eagle.

Q: Because of their endangered species status, all eagle feathers are illegal, I have to ask -- how did you manage to get one of those?

A: I went down to the Museum of Natural History near the University of Southern California. I knew someone in their bird department and he found, stored in a drawer, one huge wing feather from a golden eagle. I took it up on the roof, photographed it and returned it. Then later, I digitized that in PhotoShop, curved it a little bit so it would arc with the shape of the DVD and design and I put six of those on there.

The other elements on the disc include images of the spacecraft, the probe, Saturn and Titan, and an image of the Earth taken by the European Space Agency's METEOSAT 3 in 1991, which showed most of the countries from where the signatures came.

Q: Tell me more about the signatures and the letters that came in. Was there any one that moved you most?

A: I think the one that teared a lot of us up was a young girl named Hillary Moore. According to her father, she had loved space and was always fascinated by the things we did on these robotic missions, but she was very ill, and died at the age of 15 of congestive heart failure. Her father mailed in the page from one of her school notebooks where she signed her name many times back in her happier days before she became ill and he asked if we would fly the entire page. We had a rule of only one signature per person, but there was no way we were going to refuse that request, so we scanned her page of several signatures and flew that. The family was enormously thankful. A book was written on her life and the family mailed me a copy and I was really touched by that.

Q: Were there any unusual submissions, weird submissions?

A: We had to debate this issue of pets, because people sent in paw prints from their pet dogs and cats. We knew that pets are often loved like family members and are very important. I know this. I just lost my Sheltie, Ben. Since we were putting all this on a DVD, we had the capacity -- that was never an issue at that point -- so Planetary Society volunteers then had a few paw prints to scan.

Q: I bet they loved that though --

A: They did. And you know it was kind of refreshing. I would go to The Planetary Society and see them in groups scanning and sorting, and someone would say, 'Hey, look here -- here's a wonderful print' or 'Here's a wonderful this or that.' It was something that added a little interest to the job they were doing. So some beloved pets have their spore aboard Cassini.

Q: Now how, exactly, was this disc full of signatures attached to the spacecraft?

A: We put the disc inside a very, very shallow aluminum box, with two plates around it to protect it from micro-meteoroid damage -- probably for about 1 million years or more, and then put a thermal blanket flap over that aluminum box after mounting it to a pedestal on the side of Cassini -- and that's where it is right now -- about to enter orbit around Saturn!

Q: You just mentioned it being protected for 1 million years, but what, exactly, will eventually happen to the signature disc at the end of the day?

A: That's a great question and we just don't know yet. The final orbit for Cassini at the end of its four-year tour of the Saturnian system will not be chosen until very late in the mission, probably in 2008, so we'll just have to wait and see. And if there’s enough hydrazine on board to continue orbiting Saturn and doing great science, I’m sure that the project will request extended mission funding. In any case, when the mission is eventually over, they will have to make a decision about how best to deploy the spacecraft.