![[Figure 1: View of GROSS Display]](3_19_1.gif)
SO96.3.19
Shaun Phillips
National Aeronautics and Space Administration, Mail Stop: EO47
Marshall Space Flight Center, AL, USA 35812
Fax: 205-544-5873. E-mail: shaun.phillips@msfc.nasa.gov
Abstract: This paper discusses the Graphical Observation Scheduling System's (GROSS's) functionality and editing capabilities. GROSS was developed to replace a suite of existing programs and the process built around them. Limited data visibility and an awkward, outmoded user interface design were characteristic of this process. Numerous hours were spent using the process developing and modifying observation schedules for the first Astronomy (ASTRO-1) Spacelab mission. The mission planners for second Astronomy (ASTRO-2) Spacelab mission envisioned a new software tool that would combine the functionality from several of these programs and provide a graphical user interface (GUI) that would give more data visibility and new editing functionality. GROSS was created using a programmer to develop the GUI and a mission planner for expertise on the current process and programs. It binds an X-Windows/Motif GUI with existing mission analysis functionality. The ease in editing provided by this approach greatly enhanced the efficiency of the ASTRO-2 mission planners throughout mission preparation and real-time execution.
The need for a new method of scheduling observations was driven by the intense and time consuming process employed for ASTRO-11. This process was built around multiple programs with limited visibility of the schedule data and an awkward, outmoded user interface design. With the availability of graphics workstations, the mission planners for ASTRO-2 saw the possibility for the development of a new software tool that would consolidate functionality from the original planning tools into a single program providing a method for graphically building and maintaining the observation schedule. This new tool would provide additional data visibility through the GUI and incorporate both existing and new techniques for manipulating the schedule. This new tool, known as GROSS, was developed in under a year using a programmer to build the GUI and an experienced mission planner for expertise on the existing mission planning process and tools. It was developed in both the C and Fortran programming languages using MIT's X Windows System ™ XR11R5.
This paper discusses the capabilities of GROSS , in particular, the data visibility and editing. The data visibility is discussed in the GROSS Display Overview section. This section describes the display and the functions available through the display. The Edit Function Overview section discusses the edit functionality found within GROSS. In addition, brief discussions of other embedded functions will also be provided.
Data visibility in GROSS is provided through a graphical display. The display provides a representation of the data required to build a new observation schedule or to rapidly modify an existing observation schedule. The interface follows the guidelines proposed in the OSF/Motif ™ Style Guide Release 1.12 and recently developed in-house standards for X-Windows programs. These guidelines were used to drive the basic look and feel of the display, including screen layout and mouse button usage.
The GROSS display is initially blank after initialization. Several existing data files need to be loaded to make GROSS an effective tool. These files include a node file, which contains the orbital ephemeris data, a target file, which contains selected schedule items other than the observations, a South Atlantic Anomaly (SAA) file, which contains the times the orbiter is in the SAA, an attitude timeline file, which contains orbiter attitude timeline information, and the Science Plan, which is an ASCII file, containing the observation schedule. If the schedule is still in the development process, the Mission Target List (MTL) file is loaded. This file contains a list of all possible observation targets for the ASTRO-2 mission. Several features, such as feedback, mnemonics, accelerator keys, and cross-hairs, are built into the GROSS display. Feedback on warnings and errors is provided through a message area located at the bottom of the display and through informational boxes. The mnemonics and accelerator keys are available to speed the access to commonly used functions. A cross-hair function providing the time to the nearest second is available within the graphical area of the display. Color is used throughout GROSS to emphasize special data states. The use of color is discussed with the appropriate function.
The GROSS display consists of several distinct areas. These areas are identified on Figure 1. They are the menubar, the tickmarks, the Schedule Display Area, the Limb/Ram Plot Area, and the manual text editor area. Each of these parts has a unique purpose to play in the use of GROSS.
As is standard in Motif programs, the menubar resides at the top of the display allowing access to a majority of the functionality of GROSS. The menubar's pulldowns group the functions as outlined in the Motif Style Guide. From left to right on the menubar, the pulldowns are: File, Edit, View, Options, and Help.
Actions performed on files and actions that affect the entire program are available under the File pulldown. Access to the open file and write file functions are provided from this menu. In addition, the capability to gracefully exit the program is provided here. The Edit pulldown contains the capabilities to act on the data. From here, the user can initiate various editing techniques, including creating new scheduled items, deleting scheduled items, and undoing edits. These capabilities will be discussed in more detail in the Edit Features section of this paper. Under the View pulldown, the opportunity to review the schedule itself and view more detailed information about the schedule is provided. The schedule can not be modified from the View pulldown options. However, from this pulldown, orbiter shadow times may be viewed and printed, statistics built, viewed, and printed, and the schedule verified. Also, information about specific observations may be viewed and the selected data set loaded into the text editor for further review. Customizations are accessed from the Option pulldown menu. In GROSS, these include options to select a default time span and format, and to print plots reflecting the scheduled items. The on-context Help available on GROSS is available from the Help pulldown, which is located to the extreme right on the menubar.
Two tickmark areas on the GROSS display provide the time references for the graphical display. The sets of tickmarks surrounding the graphical region reference the current time span. The tickmarks beneath the scroll bar reference the mission duration. These tickmarks reference the current time span to the time span of the entire mission. The scroll bar used in the GROSS display is a pan-zoom scroll bar, developed in-house. This scroll bar controls the duration of the current time span (zoom) and location of the time span (pan).
The Schedule Display Area is the graphical region beneath the current time span tickmarks. The labels to the left denote the data provided within the display. As seen in Figure 2, these labels are Miscellaneous, IDOP, Science Observations, Maneuvers, SAA, and light, dark, and 0 degree limb A/L (acquisition/loss). To the right of the labels, within the graphical area, the data is represented as bars, with the start and stop time of the data being the edges of the bars. The following modes are available for each bar:
![[Figure 2: Schedule Display Area]](3_19_2.gif)
To limit crowding within the Schedule Display Area, the light limb, dark limb, and 0 degree limb bars for scheduled observations are only provided when the observations are selected or have been loaded into the text editor. The limb data is represented as black outlined boxes and is located directly beneath its associated observation.
The shadow times are visible on the display as vertical, gray bars behind the other data. An option to view the actual start and stop times of the shadows is available from the View pulldown menu.
The Limb/Ram Plot Display Area is immediately below the Schedule Display Area. Figure 3 shows a detailed view of this area. If the schedule and ephemeris data are available, the limb and ram plots for the science observations are shown in this area. The Sun, Moon, and Beta Angles for selected observations are also displayed. The legend and scale are to the left of the plots. Due to visibility concerns, these plots are only displayed if the selected viewing area is 24 hours or less.
![[Figure 3: Limb/Ram Plot Area]](3_19_3.gif)
The manual text edit area is at the bottom of the display. This area provides the opportunity to manually edit loaded schedule items. It also provides a view of more detailed schedule information than can be provided in the graphical portions of the display. The text editor is discussed in detail in the Manual Editing section of the paper.
Inherent in GROSS are the functions required to both build and modify an observation schedule. These functions are available from the Edit pulldown menu on the menubar and through the graphical and manual editing capabilities of the display.
Interaction with a majority of the editing features within GROSS is available through the Edit pulldown menu. With the exception of two unique functions, the available functions fall into four major categories: modify the duration, move in time, add to the schedule, and delete from the schedule.The two unique functions are renumbering observation identification numbers and undoing graphical edits. The renumber feature is useful when the identification numbers have become out of sequence during the iterative add, move, and delete process of building a schedule. The undo feature allows the last graphical edit performed to be undone. This feature allows some trial and error in the schedule modification process.
The capability to modify the duration of scheduled observations is available through the chop targets and extend targets functions. Both of these functions require the selection of which observation time point to modify (the start time, stop time, or both), which limb to use as a constraint (light, dark, or 0 degree), and the time span over which to perform the action. With this information, the chop targets function shortens the observations within the time span; the extend targets function lengthens the observations. The results of these actions are immediately applied to the schedule and are visible in the Schedule Display Area.
The move maneuvers and time bias functions provide the capability to move items in time within the schedule. In both functions, positive time durations move items forward in time; negative durations move items back in time. The move maneuvers function slides attitude maneuvers in time within the selected time span. Time bias acts on the entire schedule, moving all scheduled items in time. The results of these actions are immediately applied to the schedule and are visible in the Schedule Display Area.
Adding items to the schedule is provided through two functions, add target and add activity. The add activity function is straight forward, allowing manual entry of the start and stop time for the new activity, the activity name, and the right ascension and declination, if required. Activities named IDOP or MANEUVER are grouped with their associated data, otherwise, the new activity is grouped with the miscellaneous data. The new activity is immediately added to the schedule and is visible in the Schedule Display Area.
The add target function is more complex and consists of two steps. Figure 4 shows the implementation of the add target function interface.
![[Figure 4: Add Target Function]](3_19_4.gif)
The first step builds a subset of the mission targets list (MTL) that meets the criteria for the new observation and the second step is the actual addition of the target to the schedule. For the ASTRO-2 mission, criteria for selection into the subset included the instrument, target priority, constraint code, class, and subclass. As shown in Figure 4, the information from the created subset is at the bottom of the add target interface. To add an observation, the window is entered and an observation is selected from the subset. If a time point to schedule the selected observation within the window is found, the observation and it's associated activities are displayed in green in the Schedule Display Area at the correct time until the new observation is either accepted or denied. If the observation is not accepted, there is no impact to the schedule. The accepted observation and its associated activities are immediately applied to the schedule and are visible in the Schedule Display Area as scheduled items. If a time point to schedule the selected observation is not found, the user is notified of the failure and is returned to the add target interface.
Three methods for deleting items from the schedule are provided: delete by time span, delete by activity, and delete selected. Delete by time span deletes all items in the schedule within the selected window, including any items that overlap the window endpoints. Delete by activity deletes all instances of an activity within the schedule. Activities are scheduled items that are needed in support of observations that involve crew, orbiter or the Instrument Pointing System. Observations can not be deleted with this function. Delete selected deletes all currently selected items. The deletes are all performed immediately on the schedule and the deleted items are no longer visible in the Schedule Display Area. Selection of items in the schedule is discussed in the Graphical Editing section of this paper.
The graphical editing functionality within GROSS is available in the Schedule Display Area. As discussed in the GROSS Display section, the status of each item in the display can be visibly tracked through the use of color and display modes. Prior to initiating the graphical edit an item , the item must be selected. Items may be selected singly or in groups of up to 20. Three selection methods are available, as described below.
Once the items to be edited have been selected, three methods for editing are easily accessible. These methods are drag and drop, resize, and load into the text editor.
Drag and drop editing allows selected items to be easily moved in time within the schedule. This function does not affect the duration of selected items. The Drag button on the mouse is pressed and held on the selected item or group of selected items. A dashed line box is drawn around the selected items. The box is then dragged with the mouse while the Drag button is still held down. The items are dropped at their new location when the Drag button is released. More precise moving may be done while still dragging using the right or left arrow keys to fine-tune the placement of the selection box. This allows the user to select the placement to the second, required for the precision scheduling needed for ASTRO-2. This capability is enhanced through feedback provided in the upper left corner of the display showing the current location of the selected group during the drag. With the exception of SAA and shadow data, the scheduled items in the Schedule Display Area can be modified with this method. This change is made in the schedule as soon as it is performed; however the edit can be undone with the undo function until another edit of any kind is performed.
The resize capability provides a method to change the duration of a selected scheduled item. Resize is performed by pressing and holding with Shift-Drag button on a selected item and dragging the mouse. Whether the start time or the stop time is modified is dependent on where the resize is initiated; if the initial click was nearest the start edge, the start time is modified, if the initial click was nearest the stop edge, the stop time is modified. Precision resizing, to the second, can be achieved through use of the arrow keys as discussed in drag and drop. Feedback is provided in the upper left corner of the display showing the initial time and the changes in duration of the selected item during the resize. Only one item can resized at a time. This change is applied to the schedule as soon as it is performed; however the edit can be undone with the Undo function until another edit of any kind is performed.
Manual editing is supported within GROSS in the manual text edit area. This region consists of the text editor and edit action buttons as identified in Figure 5. The text editor allows manual editing of scheduled items and is an alternative method for viewing the detailed information about these items. The items are initially loaded into the editor through the use of the load selected function from the View pulldown menu. The editor places each item in its own row. Labeled columns identify the available data. If necessary, vertical and horizontal scroll bars are provided to allow viewing all the data within the editor. Individual fields to edit may be selected using the mouse. Additionally after initially selecting the text editor, the keyboard may be used to maneuver through the data fields.
![[Figure 5: Manual Text Edit Area]](3_19_5.gif)
Editing support is provided within the editor. GROSS protects the fields that are not suitable for editing by not allowing editing within those data fields. Invalid characters for a data field can not be entered. Data fields requiring data to be in specific ranges support data validation. Color is used within the text editor to reflect the status of each item: black is unchanged data; red indicates an error; and purple indicates an edit has been made. The edits made within the text editor are reflected in the Schedule Display Area, but are not applied to the schedule until the changes are committed.
The edit action buttons,perform actions on the contents of the text editor. The available actions are commit, clear, time order, and print. Clear empties the text editor; this action does not save the changes to the schedule, however the user is informed and given the option to cancel the action. Commit saves the current data in the text editor into the schedule; the user is informed if errors still exist and is given the option to cancel the action. Time order reorders the data within the text editor into ascending time order. A printout with the current text editor data is available through Print.
The capabilities of GROSS as discussed in this paper gave the ASTRO-2 mission planners a more efficient method of developing and modifying the observation schedule than had previously existed for ASTRO-1. GROSS provided both the data visibility and updated user interface design through the X-Windows/Motif display that were lacking in the ASTRO-1 process. Also provided were the functions required to support editing, both over large time frames within the schedule, such as chop targets and time bias, and on an individual item basis, such as resize and text editor. Both the mission planning team and the Principal Investigators (PIs) benefited from this new software tool. By using GROSS, the Principal Investigator's were able to build a preliminary schedule to review and to support the schedule development of the mission planning team. GROSS enabled the ASTRO-2 mission planners to rapidly build and update observation schedules in support of both pre-mission planning and real-time operations.
1O.T. Guffin, C.D. Olsen, J.F. Onken, and R.L. Stewart, "A Practical Approach to Astronomy Mission Replanning", AIAA Space Programs and Technologies Conference, March 24-27, 1992
2OSF/Motif ™ Style Guide Release 1.1, PTR Prentice-Hall, Inc., Simon & Schuster Company, Englewood Cliffs, New Jersey, 1991