An Internet-based software system, called the "Web Interface for Telescience" (WITS), enables geographically dispersed scientists to participate in scientific exploration of remote planets by use of instrumented landers and robotic vehicles called "rovers." WITS at a previous stage of development was described in "Web Interface for Telescience" (NPO-19934), NASA Tech Briefs, Vol. 21, No. 8 (August 1997), page 34. Since that description was published, major additional features have been incorporated. Originally intended for use in a rover mission on Mars in the year 2001, WITS reached sufficient maturity early enough to have limited use during the 1997 Mars Pathfinder mission. Also, WITS will be used in the 1998 Mars Polar Lander mission.
One basic purpose of WITS is to enable mission scientists at their home institutions to collaborate, quickly and efficiently, in planning planetary robot operations without having to travel to a central control station at NASA's Jet Propulsion Laboratory. This is accomplished by use of interactive displays of images of terrain from rover-mounted video cameras, terrain maps derived from such images, and other data from rover-mounted instruments. Provisions for measuring and annotating terrain features and planning mission activities are included in the displays. Scientists and engineers can, for example, use WITS displays to enter such command data as way points on a traversal of terrain, plus scientific observations and/or engineering tasks that the rover must perform at some or all way points.
Another basic purpose served by WITS is to communicate mission data to the public as quickly as possible. To serve this purpose while providing an element of security, WITS is constructed as two physically separate, parallel systems: the mission system and the public system (see figure). Both systems receive data updates from the rover mission, and both systems contain the same software, including software for planning rover tasks. However, only the mission system commands the rover. The planning software in the public system can be used only to perform simulations that reside solely on users' computers. In other words, the mission and public systems are nearly identical, except that data are not transmitted from the public to the mission system.
The WITS software is divided into two parts: (1) the client part, which is executed on a user's computer, and (2) the server part, which is executed on one server computer for the mission system and on another server computer for the public system. The servers communicate with the clients and perform such computationally intensive operations as processing of stereoscopic images and generation of range maps. The mission server also acts as an interface with the communication system that conveys data to and from the rover and its spacecraft. The servers maintain a common data base, including information on the current mission plan. Collaboration is greatly facilitated in that the same video images, instrument readouts, and planning information can be viewed simultaneously by all users. However only mission participants (who must prove authorization by logging onto the mission server by use of passwords) can modify the common data base.
The client part of the WITS software is written in the Java computing language as a Java applet and is automatically downloaded onto the user's computer by the user's own web-browser software. This feature makes WITS available to many users and executable on almost any computer at any site. The great advantages of this feature are that the collaborating team and public audience can be expanded at little cost, and that each user has immediate access to the most recent version of the client part of the WITS software.
Geographically Dispersed Computer Users have access to rover-mission data, though only scientists and engineers directly involved in the mission can affect the mission. Members of the general public can use planning software to plan and simulate rover activities on their local computers only.
This work was done by Paul Backes of Caltech and Kam S. Tso and Greg Tharp of IA Tech, Inc., for NASA's Jet Propulsion Laboratory. NPO-20374