When submitting a new acquisition tasking request please take into account the following considerations.
SAR Imagery Product Tasking Categories
Capella provides users with the flexibility to submit new acquisition tasking requests in three different SAR imagery product categories in order to acquire data products that meet specific project needs and satisfy unique mission requirements. When configuring a new acquisition tasking request users can select from Standard (default), Extended or Custom product categories:
- Spotlight - 15° to 40°
- Sliding Spotlight - 15° to 45°
- Stripmap - 15° to 45°
Custom SAR imagery products tasking allows users to specify additional advanced SAR imaging acquisition parameters such as scene length and spatial resolution. With Custom products tasking there is also the option to acquire imagery in the full accessible range of look angles:
- Spotlight - 5° to 40°
- Sliding Spotlight - 5° to 45°
- Stripmap - 5° to 45°
Constellation Imaging Latitudes
At the time when this help article documentation was last updated Capella Space has a constellation of multiple SAR satellites in a mix of mid-inclination orbit (MIO) and sun-synchronous orbit (SSO) which impacts that latitude range that can be imaged by any given satellite. However, Capella's constellation tasking system automatically manages individual satellite latitude constraints so for any given tasking request the available imaging latitudes of the entire constellation (currently +87.4°N to -87.4°S) is considered by the new acquisition scheduler.
Furthermore, at this time the ability to submit an individual tasking request for polygon areas-of-interest (AOIs) which require multiple image scenes to cover the entire acquisition area is limited to mid-latitudes (currently +65.0°N to -65.0°S) within the self-serve tasking system exposed to users in the Capella Console web application and Capella API. At the upper latitudes above this range either separate point location single-scene tasking requests can be submitted to cover the AOI area or Capella Space can assist with management of large-area acquisition campaigns.
Here is a global map which illustrates the current imaging latitude capabilities of Capella's SAR satellite constellation:
Area Of Interest (AOI) Complexity
The tasking system will accept point and single polygon AOIs. The tasking system will only accept polygons with a single line string and less than 250 vertices (clicked points when creating an AOI). It will not accept polylines, multi-polygons, or self-intersecting polygons or polygons with holes.
There are maximum AOI area size limits for polygon tasking requests based on the imaging mode and acquisition window duration. If a new tasking request for an AOI area is rejected or expired it may be too large to collect within the acquisition window duration (time between 'window open' and 'window close'). In these cases please contact firstname.lastname@example.org for advanced assistance with large-area imaging acquisition campaigns.
Point Target AOI Imaging
When a point target AOI is submitted, at least one standard nominal scene will be acquired, centered on the submitted point. The extent and orientation of the imaged area will depend on the imaging mode and orbit of the satellite.
Polygon Target AOI Imaging
When a polygon target AOI is submitted, the system will determine the number and orientation of images needed to cover the AOI. All images for a tasking request will be collected in either an ascending or descending pass orientation, with the orientation aligned with the inclination of the orbit of the satellite. The system will optimize the collection of the area of interest for efficient area coverage and collection time within the designated acquisition window timeframe.
Tasking Request Rejected Workarounds
If a new acquisition tasking request is rejected there are several workaround options to consider when attempting to resubmit the request in an effort to increase the likelihood of successful scheduling:
- Make sure tasking request aligns with current constellation imaging latitude constraints
- Reduce AOI area size for rectangle and single-polygon acquisition requests
- Increase acquisition window duration (timeframe between window open and window close)
- Eliminate orbit state (ascending/descending) constraints
- Eliminate observation direction (left/right) constraints
- Consider selecting the Extended product category which increases imaging opportunities
- Consider setting the window open to a future date when more imaging capacity may be available
Users have the option to set the acquisition window duration (i.e. the duration between window open time and window close time) to a period longer than the tasking tier for cases where they would accept data collected beyond the tasking tier timeframe. For example, a user can submit a tasking request with the following configuration:
- Window Open = 1/01/2021
- Tasking Tier = 7-Day
- Window Close = 1/23/2021
- Window Duration = 23 days
In this case once the tasking request enters the scheduling window it will be repeatedly processed by the scheduler every 15 minutes. The tasking request will sit in the schedule queue as "Active" and be processed every 15 minutes until it can definitively be "Accepted" (i.e. AOI can be fully collected in the active 7 days being scheduled) or the T-minus 7-Day point (i.e. the tasking tier length) is reached on 1/16/2021 at which point the request will be definitively set to a final status of "Accepted" (i.e. entire AOI can be collected), "Expired" (i.e. only a subset of AOI can be collected) or "Rejected" (i.e. none of the AOI can be collected).
Time Between Tasking Request Submission and Window Open
There are currently no limitations on how far in advance you can place your tasking request. A new acquisition tasking request can be submitted to the scheduler queue any time prior to the user's desired window open start time and will be evaluated once the rolling one-week-out scheduling window horizon is reached.
The scheduler runs at least every 15 minutes to process tasking requests for the upcoming week (i.e. a rolling one-week-out scheduling window of requests is processed at least every 15 minutes). The system processes new requests asynchronously as they are received. There is a 15-minute timeout on each processing job. If processing does not complete within the 15-minute limit, the request will be marked as “Error”. If this occurs, consider resubmitting a new request with a shorter window duration or a smaller AOI (if a polygon). Once the request has been processed it will wait in the “Review” state and not be processed for scheduling until the user approves the cost or had submitted the request with “Pre-Approval” enabled.
The scheduler runs on a 15-minute cadence, processing requests that have reached the “Submitted” status (cost has been pre-approved or the cost estimate has been manually approved) every 15 minutes. When the request reaches the “Submitted” state, it will wait until the next new scheduling task starts before it is evaluated. It may also take up to 15 minutes for the scheduling process to run, which means it may take up to 15 minutes for a tasking request to move from the "Submitted" status to an "Accepted", "Active", or "Rejected" status.
The current scheduling window is 7 days, which means that when the scheduler runs it evaluates new tasking request where the window open time of the tasking request falls within the next 7 days. If the window open time of the tasking request falls beyond the current scheduling window, then it will not be evaluated for scheduling until a later time when the window open of the request falls within the scheduling window.
If the period between the tasking request window open time and window close time is longer than the scheduling window, the tasking request may have an "Active" status, which indicates that the entire tasking request cannot be fulfilled within the current planning window, but may be fulfilled within subsequent planning windows. The status of the request will move from "Active" to "Accepted" when all imaging has either been completed or falls within the current scheduling window.
Scheduling of Tasking Requests
The constellation tasking system continually rebalances the new acquisition schedule in a manner that maximizes utilization of constellation imaging capacity while honoring the acquisition window timeframe and tasking tier constraints of all requests. Capella reserves the right to adjust the timing of tasking requests as long as the movement is within the user requested acquisition window duration. In other words, tasking requests may be automatically rescheduled by the Capella system within the scope of the requested window duration. For example, if a user has requested an 8 day imaging window, Capella may move the time of imaging anywhere within that 8 day window.
Tasking Request Priority
Capella’s tasking tiers include an element of prioritization. The order of priority is: 1-day, 3-day, then 7-day. If a 1-day tier request is placed at the same time as a competing 3-day tier request, the 1-day tier request will be scheduled with higher priority. However, if the 1-day tier request is placed after the 3-day tier request has already been accepted, and there is no available imaging capacity in the region within the associated time window, the 3-day tier request will not be removed from the schedule to accommodate the 1-day tier request. Tasking requests that are processed within the same scheduler run are evaluated with a heuristic that maximizes utilization of constellation imaging capacity while giving a secondary priority preference to new acquisition requests that were submitted to the queue at an earlier date.