Eos, Vol. 80, No. 14, April 6, 1999

S.,St. Petersburg, FL 33701 USA; E-mail: carib@ carbon.marine.usf.edu.

References

Candela, J.,"CANEK": Exchange Through Yucatan Channel and Upwelling Dynamic over the Yucatan Shelf, paper presented at Conference on the trans­port and linkages of the Inter-America Sea, Cozumel, Mexico, Nov. 1-5,1997.

Cochrane,! D.,The Yucatan Current, upwelling off the Northeastern Yucatan, and currents and waters of Western Equatorial Atlantic, Oceanography of

the Gulf of Mexico, Progress Report. TAMU, Ref No. 66-8T, pp. 19-38,1966.

Melo,N.,R.Perez,and S. Cerdeira.Variacion espacio-temporal de los pigmentos del fitoplancton en zonas del Gran Caribe a partir de im genes del sat lite Nimbus 7 (CZCS),Avicennia, 3, pp. 103-116, 1995.

Merino, M., Upwelling on the Yucatan Shelf: Hydrographic evidence,./ Mar.Syst, 13, pp. 101-121,1997.

Muller-Karger,EE., J.J.Walsh, R. H. Evans,and M. B. Meyers, On the Seasonal Phytoplankton Concen tration and Sea Surface Temperature Cycles of the

Gulf of Mexico as Determined by Satellites, J. Geophys. Res., 96, pp. 12,645-12,665,1991.

Muller-Karger, EE., FM.Vukovich./wr Field Processes and Red Tides in the mid-IAS and eastern GOM, paper presented at Conference on the transport and linkages of the Inter-America Sea, Cozumel, Mexico, Nov. 1-5,1997.

Perez, R.,et al.,Reporte de un Frente Hidrologico al NE de la Peninsula de Yucatan, Manifestaciones Fisicas, Quimicas e Hidrobiologicas (online), Boletin de la Sociedad Meteorologica de Cuba, 2(7) , July 1996; available at http://www.met.inf.cu/ sometcub/boletin/default.htm upon request.

Aerobot Measurements Successfully Obtained During Solo Spirit Balloon Mission PAGES 153,158-159

Robotic balloons, also known as aerobots, have become candidates for collecting atmos­pheric data and detailed surface observations ofVenus, Mars, and Titan. A mission to Venus over a decade ago used two of them. Their inclusion last year in attempts by a balloonist to circumnavigate the Earth aptly demonstrat­ed their utility for remote sensing and in situ observations of planetary atmospheres.

To simulate aspects of an aerobot mission, a small payload to measure local atmospheric conditions and balloon position and velocity was included on Solo Spirit "Round the World" flights during January and August of last year.These missions, flown in Roziere bal­loons, were attempts by Steve Fossett to become the first person to circumnavigate the globe in a balloon without stopping. Neither attempt was successful, but the aerobot came through with flying colors.

Data were recorded and relayed to mission control every hour under nominal conditions using a satellite automatic phone system. The January attempt began in St. Louis and ended in Russia. The attempt in August began in Argentina and ended in the Coral Sea. The data were used in real time to refine satellite-based weather predictions and demonstrate the value-added nature of analyses that include in situ measurements and orbital observations. The data also documented the dynamics of the balloon, including altitude fluctuations associated with autopilot burns, rotation rates while in particular weather sys­tems, and a rapid descent to de-ice the bal­loon. Data and documentation for the flights are on the Solo Spirit Web site (http://solospirit. wustl.edu).

The two aerobots that went to Venus, on the Soviet/French Vega mission, drifted in the atmosphere for the equivalent of 2 Earth days,sending back information on tempera­ture, pressure, aerosol properties, and plat­form velocity [Crisp et al., 1990]. Recent developments in deployment mechanisms

and miniaturization of instruments make aerobots viable candidates for another mis­sion to Venus and missions to Mars and Titan, a satellite of Saturn.

A Mars aerobot, for example, might focus on in situ atmospheric measurements to validate observations obtained at the same time from atmospheric sounding by an orbiter. Alter­nately, the mission might focus on drifting only hundreds of meters above the surface, acquir­ing high spatial resolution imaging spectrome­ter observations of the ancient cratered ter­rains and searching for morphological and mineralogical evidence of ancient fluvial and lacustrine activity Spatial resolutions of better than a meter/pixel would be possible, filling the gap between wide area coverage at mod­est resolution from orbit and detailed but lim­ited coverage from landers and rovers.

In preparation for mission opportunities, a number of technology development efforts and demonstrations are under way under the auspices of the Advanced Technology Program at the Jet Propulsion Laboratory (http://robotics.jpl.nasa.gov/aerobot/). It was as part of this program that a small

payload was designed and built for the Solo Spirit.Those missions took place from December 31,1997 to January 5,1998, and from August 8 to 16,1998.

Payload Design

The payload was designed to measure atmospheric temperature, pressure, relative humidity upwelling sky radiance integrated over 0.4 to 1.0 micrometers, vertical wind velocity payload internal temperatures and voltages, and payload position and velocity (Figure 1). The latter two measurements used a geopositional satellite system included with the other hardware components. The payload also included command and control systems and a magnetic storage system. It was mount­ed on the side of the gondola and connected to a satellite telephone.

The payload was to record wind velocity every second, geopositional data every 10 seconds, and other measurements every minute, and was to store the data and relay the information by telephone using automat­ic dialing capabilities every hour during the flight. During the missions, the raw data were converted to time-ordered geophysical units at the Jet Propulsion Laboratory and then electronically transferred to Washington University's Solo Spirit mission control for validation and near real-time posting on the Solo Spirit Web site.

A second transmission mode involved those times when the balloon descended below

Antenna

Radiometer [

Aerobot payload

Radiometer

Fig. 1. Schematic showing the aerobot payload and a view of the payload mounted on the side of the gondola.

Eos, Vol. 80, No. 14, April 6, 1999

Fig. 2. Solo Spirit flight paths for January 1998 (Northern Hemisphere) and August 1998 superimposed on a Mercator map. Black arrow above the January track denotes loca­tion of rapid descent for de-icing purposes. Color-coded shaded relief map is shown for the continents and blue indicates the oceans. Cloud map generated by the University of Wisconsin using GEOS, Meteosat, and CMS satellite data is overlain. Cloud data are shown for the time just before the end of the August mission. Note the dense clouds over the Coral Sea—a group of thunderstorms that were impossible to avoid. Original color image appears at the back of this volume.

Fig. 3. Polar stereographic views of the South­ern Hemisphere showing water vapor abun­dances (brighter areas have more water vapor than darker areas). The images were generated by the University of Wisconsin from infrared satellite data. Solo Spirit tracks are overlain, with water vapor data showing the atmospher­ic conditions corresponding to the track end points. Note the cyclonic systems to the south of the tracks and the manner by which the bal­loon maintained a net easterly direction by using the northern sides of these low pressure zones. Times are in UTC. Original color image appears at the back of this volume.

Eos, Vol. 80, No. 14, April 6, 1999

*mm *mm *.»» imm r»m

Fig. 4. Plots of altitude (above Worid Geodetic System 84 datum), temperature, and relative humid­ity, illustrating use of the aerobot data that determined that a rapid descent path was taken to de-ice the balloon. An icing problem was reported by the pilot around 0545 UTC. Aerobot data began to be broadcast in the real-time mode at 0615, including data buffered before this mode began. Original color image appears at the back of this volume.

2500 m.Then the system was to kick into a real-time transmission mode in which data were acquired and broadcast every 2 to 5 minutes.The purpose was to track atmospher­ic and balloon dynamics during rapid descents and to pinpoint a landing site for rescue purposes. Because the type of phone coverage used was focused over the conti­nents, the expectation was that data relays would be missed over the open oceans.

The first 1998 mission began with liftoff from St. Louis, Missouri, and ended in Krasnodar, Russia, near the Black Sea (Figure 2). Unexpected path diversions to miss a storm system in the North Atlantic and a faulty heater system in the gondola's cabin forced termination of the attempt. Several hundred kilobytes of telemetry data were acquired, although the occasional inability of the phone system to link up to the satellite resulted in a number of data gaps, even over the continents. Among other factors, the prob­lem had to do with multipath transmissions caused by the reflective nature of the alu-minized balloon coating.

Controlled Crash Landing

The second mission began in Mendoza, Argentina, and ended with a controlled crash-landing in the Coral Sea east of Australia (Figure 2). With a refurbished payload and centering of the phone antenna within the balloon, approximately 2 megabytes of telemetry data were collected, corresponding to 19 megabytes of processed data.

The end of the August mission was sudden indeed.The balloon ruptured at an altitude of approximately 9200 m during a rapid ascent in a thunderstorm. The subsequent rapid descent precluded satellite lockup for the real-time mode of the payload, although the lack of a standard hourly broadcast was fur­ther evidence of a problem with the mission. Fossett was rescued, but the balloon, gondola, and payload have not been located.

In addition to data collected during the two missions, the Solo Spirit Web site has posted summaries of weather systems encountered and maps that show the ground-track of the balloons superimposed on satellite-derived maps depicting clouds and atmospheric water vapor abundances (Figure 3).These maps were generated by the Space Science and Engineering Center, University of Wisconsin, Madison, every 3 hours during the missions and posted on the Web site for use in path planning and public outreach. A Spanish version of the Web site is available for the August mission.

Aerobot observations during the January mission were used to some extent for com­parison with satellite data and path planning. However, the meteorology team was not at the Washington University mission control site, precluding close contact between that team and the aerobot team. Data gaps and the need to carefully validate the data during the first flight also made use of these observa­tions in path planning problematic.

Interestingly, the real-time mode of the pay-load did kick in over Eastern Europe, when

Fossett found that the balloon was becoming covered by ice. He began a rapid descent from approximately 6500 m to 1000 m to warm the balloon.The payload data clearly showed what was happening as the balloon moved to warmer conditions.Temperature and relative humidity both increased during descent, indicating wetter conditions at lower altitudes (Figure 4).The lowest altitudes brought the balloon into conditions warm enough to melt any ice, after which the pilot ascended back to the cruise altitude. Mission control personnel were not aware of this situ­ation until the aerobot data were brought to their attention.They then sent a message through the main communication system and received verification from the pilot that he had descended for de-icing purposes.

Meteorology Team

During the August mission the meteorology team of Robert Rice and George Dunnavan was at the same site as the mission control and aerobot teams.The meteorologists' task was to keep the balloon moving as quickly as possible on a net eastward direction while avoiding inclement and dangerous weather systems (Figure 3).The balloon also needed to stay in the midlatitudes to meet contest rules and to avoid circumpolar storms and seas in case of a water rescue.The favored weather paths were the northern sides of low pressure zones and associated westerlies, at altitudes sufficiently high to be within the lower part of the jet stream. Path planning was accomplished using satellite data, aerobot observations, and weather forecasts supplied by the National Oceanic and Atmospheric Administration to pick a set of altitudes and thus winds that would safely move the bal­loon along its net eastward path. Altitude information was broadcast to the pilot using the main communication system, and the autopilot burner system was set appropriately

Use of the aerobot data in the path planning confirmed the complementary nature of in situ observations and orbital sounding data. The value-added nature of such observations and data would be especially the case in planetary missions, since knowledge of the atmospheric dynamics of other planets is crude compared to what is known of Earth's circulation and weather systems. A more detailed analysis of the aerobot data interpret­ed within the context of the orbital observa­tions is under way (R.A. Kahn et al, manu­script in preparation, 1999).

The final operational use of the aerobot data was in tracking the dynamics of the bal­loon in mission control. This was somewhat unexpected but proved to be very valuable in documenting that the balloon was behaving normally and in understanding the dynamics within various weather systems. For example, during daylight hours the balloon rotation period of approximately 20 minutes was accu­rately assessed by tracking temperature as a

Eos, Vol. 80, No. 14, April 6, 1999

function of time. Altitude, temperature, and sky radiance data were also utilized to evalu­ate the extent to which the balloon entered into a solar soaring mode during daylight hours. In this mode, sunlight heats the helium and the balloon ascends to an equilibrium float altitude without the use of burners.

A recent development in connection with the aerobot is a Titan "aerover."This is a bal­loon that inflates as it enters the atmosphere of Titan and traverses the atmosphere making measurements while a sounding and commu­nications orbiter is overhead. After several weeks the balloon is deflated, descends to the surface, and is reinflated as a balloon-tired tri­cycle rover. This rover, capable of traversing the ice continents and seas of this outer solar system world, would last another several weeks, characterizing the ice geology and determining the composition of organic com­

pounds. Tests of the aerover are planned for this spring in the Mojave Desert (http://robotics. jpl.nasa.gov/aerobot/).

Acknowledgments

We gratefully acknowledge the Missouri Space Grant Consortium for support for the payload and for student assistants during the Solo Spirit missions. We thank the Planetary Data System Geosciences Node at Washington University for support in Web page develop­ment and operations and the University of Wisconsin for generating maps. We offer a special thanks to Steve Fossett for agreeing to include the aerobot payload on his missions and for his special care and attention to the payload and its operation during the flights. Finally, we thank the August mission meteorol­ogists, Robert Rice and George Dunnavan,for

their interest in and use of the aerobot data during the mission.

Authors

Raymond E. Arvidson, Judd D. Bowman, Edward A. Guinness, Sarah S. Johnson, S. H. Slavney, Thomas C St ein, Aaron D. Bachelder, Jonathan M. Cameron, James A. Cutts, Robert V.Ivlev, and Ralph A. Kahn For more information, contact Raymond E. Arvidson, Department of Earth and Planetary Sciences, McDonnell Center for the Space Sciences, Washington University, St. Louis, MO 63130 USA; E-mail: Arvidson® wunder.wustl.edu

Reference Crisp,D.,A. PIngersoll,C.E. Hildebrand,and R.A.

Preston,Vega balloon meteorological measure­m e n t s , ^ . Space Res., 10,109-124.

Conferees Exploring the Next Millennium of Space Exploration Focus on Education and Imagination

PAGES 154-155

Actor Robert Picardo's daughter once inno­cently asked why he drove to work. "Why doesn't a spaceship beam you up?"

Picardo, who portrays a 24th century holo­graphic doctor in the Paramount Pictures television series Star Trek: Voyager, readily acknowledges that the show is far from a doc­umentary. But he said the main role of sci­ence fiction is "to teach viewers and reader.

That theme of encouraging people, especial­ly young people, to dream and imagine hu­manity's future in space echoed throughout a conference on "Space Exploration at the Millennium," held on March 24 in Washington, DC. The day-long conference—held in re­membrance of scientist Carl Sagan and featur­ing scientists, educators, students, science fic­tion writers, and NASA Administrator Dan Goldin—occasionally included a large con­tingent of elementary school children, and the speakers often tailored remarks for them.

Franklin Chang-Diaz, a NASA astronaut who was born in Costa Rica, recalled his mother telling him in 1957 that a new star—Sputnik, launched by the Soviet Union—was at that time orbiting the Earth. Later, Chang-Diaz wrote to NASA to inquire how he could become an astronaut. As Chang-Diaz addressed the audience, he said,"I often take a good look, because I might be looking at the first person to go to Mars."

"Yesterday we walked on the Moon, tomor­row we walk on Mars," said Yvonne Cagle, one of the first African American women selected for NASA's astronaut program.

Cagle, who said she would like to be the first physician to make a house call on Mars, out­lined potential advances, including some in the field of medicine, that might derive from the International Space Station.

And Buzz Aldrin, an astronaut on the Apollo 11 mission and the second person to walk on the Moon, shared with the audience his hope that space travel soon would be available to a wide public. However, he also tempered the enthusiasm expressed by others for sending humans into deep space "until we have deter­mined it is purposeful."

Others at the conference invited more immediate public participation in space exploration. Donna Shirley, retired manager of NASA's Mars Exploration Program at the Jet Propulsion Laboratory and original leader of the team that built the Mars Pathfinder rover, outlined a series of upcoming NASA missions to Mars as well as the Mars Millennium Project. This official project of the White House Millennium Council, she said, hopes to encourage schools, youth groups, and com­munity organizations to imagine and design a livable community for 100 Earthlings trans­planted to the planet Mars in the year 2030.

Livability she said, is more than simply cre­ating a dome for people to huddle inside. Shirley said a design for a livable communi­ty also would take into consideration some bigger picture concerns, and incorporate the humanities and the arts. How would one make art on Mars, or play basketball on a planet that has three-eighths the gravity of the Earth? she asked. Shirley added that the project might encourage participants to

take a closer look at their real-life communi­ties to see what works and how they can help to improve them.

Bill Nye, who stars in the television program, Disney Presents Bill Nye the Science Guy, helped kick off another project aimed to involve students in an upcoming Martian mis­sion. Nye invited students worldwide to cre­ate a tiny experiment that would fly to Mars on board the Mars Surveyor 2001 Lander. "2001 Mars Odyssey: the Student NanoExperi-ment," a project sponsored by the Planetary Society in cooperation with NASA and some private groups, will carry a student experi­ment no bigger than 1 cm in diameter and 1 cm in height, and weighing no more than 3 grams (the weight of a U.S. penny). The size and weight are limited due to the enormous cost of carrying items into space.

What can anybody create in such a small size? Nye held up a pair of tweezers grasping something considerably smaller than regula­tion size. "This is a sesame seed," he said. "It contains all the information you need to make a sesame plant, and all the information it needs to make more plants." To drive home the point, he next held up a poppy seed.

"So, humans should be able to come up with something cool that can fit within this gigantic space," he said, adding that the exper­iment would be placed in front of a camera for the world to watch.

Nye, who portrays a zany scientist, makes a strong pitch for the importance of science education. To the symposium attendees, in­cluding the youngsters, Nye said a democrat­ic society that relies upon science and tech­nology requires a science-literate populace that understands how things work and can make wise decisions about complex issues. "My mission is to try to get people excited about science so that in the future we have more scientists," Nye said. "Pseudo science is perhaps my deepest fear. There are many