"Huygens Mission: My job and some of my Experiences"
by Miguel Perez Ayucar, SSP-2004
(March 2005)
Who am I, and what is Huygens?
At 28 years old (born 29 March 1977 in Pamplona, Spain) I am an Engineer on the Science Operations
of the NASA/ESA/ASI
Cassini-Huygens mission, in ESTEC, at the European Space Agency (ESA).
My Background and Past Experience
I graduated as a Telecommunication Engineer from the Public University of Navarra, after having completed my final year at the Polytechnic University of Torino, Italy. My postgraduate studies in Spain led me to become a Satellite Communications specialist. My first employment was in as a Satellite Analyst in the Minisat-01 Mission Control Center. After that I worked as a satellite consultant for the Spanish Ministry of Defence in Madrid. During that period the Huygens job came up at ESA, and I found it ideal since working in space exploration had long been my dream.
Huygens Mission Tasks
I started working on the telecommunications part of the mission, so it was my job to ensure that all the data gathered from the instruments on-board Huygens were successfully transmitted back to Earth. In normal missions, the Science Operations team is responsible for the day-to-day planning of the scientific observations. However, Huygens is a very special mission, because there was only one observation slot, the descent into Titan, which lasted only two and a half hours! We also did the regular probe check-outs for planning the maintenance of the instruments in transit.
For the last 18 months, we had been refining the telecommunications so that we could be sure the data would be successfully transmitted. One of our problems was the ‘Doppler’ effect (the same effect which causes the sound of a police car siren to change as it speeds past). Many things could have been done to help us minimise the Doppler effect provided the spacecraft were here with us, but since it was already in space, it was very difficult to make adjustments. All we could really do is change the trajectory or change the software. We used an engineering model of Huygens at ESOC(Darmstadt) to test that our modifications will work. For example, we warmed up the Huygens probe by switching it on four hours before the mission started, since this pre-heating improves the telecommunications. We refined our analyses of Huygens right up until the last minute.
SOI (SATURN ORBIT INSERTION) Day: 1st July 2004
Where was I when Cassini-Huygens entered into Saturn’s orbit? I was in Adelaide, Australia!! In the ISU SSP'04.
How did I live it? How was the uncertainty until signals reached Earth? Nerves were impossible to control, in fact I had to leave in one of the lectures to follow on-line the events happening. I was connected via e-mail and phone to my colleagues in JPL/NASA and ESOC/ESA controlling the status of the spacecraft as data arrived into the control centers. In one of the lectures I made a small status report to the rest of the ISU students, although no data had returned yet: it was traveling through the solar system from Cassini, in its 1:24 min one-way-light trip time.
After knowing that everything had developed nominally and we were in orbit around Saturn, I was so excited! In some way I was maintaining my job, thanks to the work done by our partners at JPL.
Cassini had been our interplanetary 'taxi' of this 7 years trip around the solar system. In the Orbit Insertion Maneuver performed the 1st July we were mere “passengers”. Not being able to control directly the sequence of events magnifies even more the feelings, tough we were completely confident on the excellent work put in place by the Cassini Team.
The first impressions and answers from my colleagues in the Huygens Mission Control Center in Darmstadt, Germany, after the SOI were eloquent. Big exclamations, joy, emotion!
When first images of Cassini arrived I was astonished by the beauty of the rings and the complex structure. But I was already thinking in the first images that were to be taken next day during the first Titan fly-by. Those observations were crucial for our team to validate the current models of Titan’s atmosphere and refine some of the mission parameters, before the fierce entry into Titan’s world.
Huygens Recovery
The communications problem discovered in February 2000 was solved with a new mission scenario. In March 2004 the Delta-FAR (Delta Flight Acceptance Review) was successfully conducted. It was a major Agency revision of the design and implementation of the recovery mission, and the changes done. We had a better understanding of Titan now than on the time Huygens was launched (Oct 1997). After implemented the recommendations from the board of the Review Panel, we were ready to encounter the mysterious moon!! Only 7 months to go!
Mission Readiness Review was successfully concluded in December. We assessed the inherent risks of this complex mission, and we had a GREEN LIGHT for primary mission and separation! Separation was smoothly executed on Christmas Day, and the entry the 14th January 2005… No fancy Christmas holydays for the Huygens Team, away from home, but it was a one-in-a-lifetime event. Everybody was waiting for this day to come!
Titan
Titan, Saturn's largest moon, is a mysterious place. It is the only moon with an appreciable atmosphere. It is thick and rich in organic compounds. Some of them would be signs of life if they were on our planet. How do they form on Titan? Will they help us to discover how life began on Earth?
Titan's atmosphere is mostly nitrogen but there are also methane and many other organic compounds. Titan is not a pleasant place for life. It is far too cold for liquid water to exist, and all known forms of life need liquid water. Titan's surface is -180°C. Could there be oceans of methane on or under the surface?
The big day: January 14th 2005 – The Descent!
All Huygens community was gathering for several weeks in the ESA Operations Center (ESOC) in Darmstad, Germany. The prior days I was really busy with last minute refinements on the entry trajectory simulations, and landing site. We were getting updated data from our colleagues in the Navigation Team of Cassini at JPL/NASA, aerodynamic coefficients and atmospheric profiles updates. Also busy with setting up everything for the data acquisition and preliminary analysis. Part of the time was spent in interviews with the numerous international media in ESOC. We had some sessions in the MCR (Main Control Room) for rehearsal of the events to come. We got used to the console system for telemetry display, and selected the relevant parameters to be displayed in the mission.
The day finally arrived. I was watching the UTC master clock in ESOC screens, it was 9:06 and the probe at this moment should be entering the higher layers of Titan’s atmosphere, far away from us, 1200 million kilometres from Earth (see artist's view below, credits: ESA/Ducros). Signals were travelling to Earth with a 1h 7 min one way light time delay. The first indication was the direct detection of the carrier by the 110 meter dish Green Bank radio telescope. Just watching at the screens, finally it was detected, around 11:20 CET. Huygens had entered in the atmosphere, deployed two of the parachutes and started to transmit. Still we had to wait for the data to be relayed by Cassini some hours after. But faces were much more relaxed now, we had picked up the signal!
It was after a light lunch when we went back again into the Main Control Room to get the data. Cassini, after listening to Huygens for more than 4 hours, pointed back to Earth and retransmitted all data gathered. Around 16:00 CET, we started to see the data. It is an amazing feeling to see the console screens filled with data, data from the other side of the solar system! All people exploded in applauses, laughs, tears...
There was a BUT, chain A didn’t work properly. STILL, redundant chain B returned all data expected, and it was being stored in our computer on Earth to be analysed in the future, for decades.
We worked all night long to provide very first results the next days. I couldn’t sleep anyway!
Titan: some preliminary results
We landed and survived in a kind of frozen -180degC dark lakebed. Images show evidence of fluid flow at all size scales: linear, complex drainage system, dark lowlands, bright highlands, rounded and smoothed pebbles and rocks, evidence of flow around 'islands', deposits of water ice and channels which could have been created by methane springs.
Titan has extraordinarily Earth-like meteorology and geology. There is a complex network of narrow drainage channels running from brighter highlands to lower, flatter, dark regions. These channels merge into river systems running into lakebeds featuring offshore 'islands' and 'shoals' remarkably similar to those on Earth. However, the fluid involved is methane, a simple organic compound that can exist as a liquid or gas at Titan's sub-170°C temperatures, rather than water as on Earth.
Titan's rivers and lakes appear dry at the moment, but rain may have occurred not long ago. Heat generated by Huygens warmed the soil beneath the probe and both the GCMS and SSP detected bursts of methane gas boiled out of surface material, reinforcing methane's principal role in Titan's geology and atmospheric meteorology -- forming clouds and precipitation that erodes and abrades the surface.
Composition of soil is dirty water ice rather than silicate rocks. However, these are rock-like solid at Titan's temperatures. A thin layer of haze observed at 21 km. Surface show marked true-color reddening with bright highlands redder than dark lowlands. Titan's soil appears to consist at least in part of precipitated deposits of the organic haze that shrouds the planet. This dark material settles out of the atmosphere. When washed off high elevations by methane rain, it concentrates at the bottom of the drainage channels and riverbeds contributing to the dark areas seen in DISR images. The finding of atmospheric argon 40 indicates that Titan has experienced volcanic activity generating not lava, as on Earth, but water ice and ammonia.
Thus, while many of Earth's familiar geophysical processes occur on Titan, the chemistry involved is quite different. Instead of liquid water, Titan has liquid methane. Instead of silicate rocks, Titan has frozen water ice. Instead of dirt, Titan has hydrocarbon particles settling out of the atmosphere, and instead of lava, Titanian volcanoes spew very cold ice. An extraordinary world having Earth-like geophysical processes operating on exotic materials in very alien conditions.
What next?
As you can imagine, there is still a lot of important work and discoveries to be made concerning Titan.
You can check the latest news concerning the mission on this European Space Agency website.
If you want to get in touch with Miguel to learn more about Titan and the Huygens mission, you may reach him
at 
.