Monday, March 7, 2016

2016-03-07: Custom Missions in the COVE Tool

When I am not studying Web Sciences at ODU, I work as a software developer at Analytical Mechanics Associates. In general, my work there aims to make satellite data more accessible. As part of this mission, one of my primary projects is the COVE tool.

The COVE tool allows a user to view where a satellite could potentially take an image. The above image shows the ground swath of both Landsat 7 (red) and Landsat 8 (green) over a one day period. 
The CEOS Visualization Environment (COVE) tool is a browser-based system that leverages Cesium, an open-source JavaScript library for 3D globes and maps, in order to display satellite sensor coverage areas and identify coincidence scene locations. In other words, the COVE tool allows the user to see where a satellite could potentially take an image and where two or more satellite paths overlap during a specified time period. The Committee on Earth Observing Satellites (CEOS) is currently operating and planning hundreds of Earth observation satellites.  COVE initially began as a way to improve Standard Calibration and Validation (Cal/Val) exercises for these satellites. Cal/Val exercises need to compare near-simultaneous surface observations and identify corresponding image pairs in order to calibrate and validate the satellite's orbit. These tasks are time-consuming and labor-intensive. The COVE tool has been pivotal in making these Cal/Val exercises much easier and more efficient.

The COVE tool allows a user to see possible coincidences of two satellites. The above image shows the coincidences of ALOS-2 with Landsat 7 over a one week period.
In the past, the COVE tool only allowed for this analysis to be done on historical, operational, or notional satellite missions with known orbit data, which COVE could then use to predict the propagation of the orbit accurately, within the bounds of the model’s assumptions, for up to three (3) months passed the last-known orbit data. This has proven extremely useful for those missions that the orbit data is known; however, it was limited to these missions.

Mission planning is another task which includes the prediction of satellite orbits, a task the COVE tool was well equipped for. However, in mission planning exercises, the orbit data of the satellite is unknown. Based on this need, we wanted to extend COVE to include customized missions, in which the user could define the orbit parameters and the COVE tool would then predict the orbit of the customized mission through a numerical propagation. I had the opportunity to be the lead developer for this new feature, which recently went live and can be accessed through the Custom Missions tab on the right of the COVE tool, as shown in the video below. This is an important addition to the COVE tool, as it allows for better planning of potential future missions and will hopefully help to improve satellite coverage of Earth in the future.


Video Summary:
00:07:04 - The "Custom" Missions and Instruments tab shows a list of the current user's custom missions. Currently, we do not have any custom missions.
00:09:03 - To create a custom mission, choose "Custom Missions" on the right panel. First, we need to "Add Mission." Once we have a mission we can add additional instruments to the instrument or delete the mission.
00:20:15 - After choosing a mission name, we need to decide if we want to use an existing mission's orbit or define a custom orbit. We want to create a custom orbit. Clicking on "Custom defined orbit" gives three more options. A circular orbit is the most basic and for the novice user. A repeating sun synchronous orbit is a subset of circular orbits that must cover each area around the same time. For example, if the satellite passes over Hampton, VA at 10:00 AM, its next pass over Hampton should also be at 10:00 AM. The advanced orbit is for the experienced user and allows full control over the orbital parameters. We will create a repeating sun synchronous orbit, similar to Landsat 8.
00:33:14 - When creating a repeating sun synchronous orbit, the altitude given is only an estimate as only certain inclination/altitude pairs are able to repeat. Thus, the user has the option to calculate the inclination and altitude that will be used.
00:37:24 - The instrument and mode, along with the altitude of the orbit we just defined, determine the swath size of the potential images the satellite will be able to take.
00:49:23 - We need to define "Field of View" and "Pointing Angle" of the instrument. We will also choose "Daylight only," our custom mission will only take images during the daylight hours. This is useful because many optical satellites, such as Landsat 8 are "Daylight only" since they cannot take good optical images at night.
01:02:06 - We will now choose a date range over which we will propagate the orbit to see what our satellite's path will look like.
01:21:18 - We can now see what path our satellite will take during the daylight hours, since we chose "Daylight only."

This project was only possible thanks to other key AMA associates involved, namely Shaun Deacon--project lead and aerospace engineer, Andrew Cherry--developer and ODU graduate, and Jesse Harrison--developer.


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