Cornell senior helps to prepare the Mars rovers' to-do lists for JPL

Wick

By Kate Becker

In his parents' living room, Justin Wick, age 2, turned the lights on. And off. And on. And off again -- until his mother arrived to rescue the unlucky light switch from her son's experiment.

Nearly two decades later, Wick '04, recalls his childhood penchant for experimenting on his parents' electronics. "I broke so much stuff when I was little," he said.

An applied engineering physics major with a minor in computer science, Wick has an instinct for tinkering that has come a long way from light switches. For the past three years he has been the only Cornell undergraduate working with the Jet Propulsion Laboratory (JPL) in Pasadena, Calif., writing software that will help scientists schedule the daily itineraries of the twin Mars Exploration Rovers (MER).

The software also will be used by the Cornell developers of the Athena science package, the six instruments in each rover's onboard laboratory. Astronomy professor Steven Squyres is principal investigator for NASA on both Athena packages, each of which includes a panoramic camera, three spectrometers and a rock abrasion tool. The rovers communicate with Earth via the three telescopes of NASA's Deep Space Network (DSN). X-band radio signals can be sent to the DSN directly from the rovers' high- and low-gain antennas or routed through the other spacecraft orbiting Mars, the 2001 Mars Odyssey and the Mars Global Surveyor. Using these spacecraft as communication messengers saves both time and energy.

Each day after the two rovers' scheduled arrival on the Martian surface next January, the MER scientists will have only a four-hour communications window in which to review the previous day's data -- everything from camera images to spectrometer readings -- and pick the most interesting targets for closer inspection by the rovers.

To do this fast analysis and build a daily itinerary, the MER team will use a Web-based virtual communications hub called the Science Activity Planner (SAP). Part database, part visualization software, SAP will enable scientists across the globe -- or merely across the room -- to inspect incoming data from the rovers and set new "targets" and "activities." Like items on a Martian to-do list, each target-activity specifies a location and a task for a rover -- not to go to the grocery store and buy milk, but to go 20 meters ahead and take spectrometer readings.

SAP has features familiar to users of programs like Access and Photoshop but, Wick said, "It's all about making things fast. Are there other things that do some of this stuff better? Sure, but none of them do it this fast and all in one place." Speed is vital because the rovers will be able to transmit direct-to-Earth for at most three hours a day due to power and thermal limitations.

Synchronization -- ensuring that scientists in different offices see the same itinerary -- is key, assuring that the same job is not accidentally done twice. A module designed by Wick helps scientists at both Cornell and JPL to share data quickly and reliably.

To help scientists get the most out of data sent from the rovers -- about 10 megabytes daily, sent at a rate about a third as fast as a regular home modem -- Wick has created software that allows the user to carefully tune the colors with which an image is displayed, adjusting the contrast to reveal subtle geological features that might otherwise be missed.

Wick's next project is a software module that will allow scientists to overlay images from two or more different instruments. By superimposing spectrometer readings on images taken by each rover's panoramic camera, scientists will be able to "know what's where at a glance," said Wick.

Once all this information is assembled, the competing demands of curiosity and caution must be balanced to send the rovers toward terrain that is scientifically interesting but still passable by a vehicle as large as a golf cart.

For each piece of software, Wick writes interlocks with dozens of others written by scientists at JPL. Remarking at the seamless result, Wick said: "Any time anything this complex works, I'm amazed."