Did you know how to buy a satellite? Well, maybe not buy, but you can task a satellite by purchasing an image from a commercial imagery products company. Hot and fresh images from their satellite constellation–just bring money!
Welcome to the world of imagery satellite tasking and the more murky aspects of satellite tasking requirements/collection management.
The name of the collection game
Imagery company DigitalGlobe recently reposted this 2010 brochure on Facebook. Why is it so interesting? Well, it’s because they tell you how you can order imagery on particularly interesting features of Earth. The brochure, titled “Tasking the DigitalGlobe Constellation,” is a great overview of how DigitalGlobe receives and manages image collection requests from customers.
The beginning of the brochure has some chest-thumping, but DigitalGlobe also wants you to know how difficult it can be to balance collection requests and manage requirements. The next few lines in the brochure, then, are all about requirements management. Requirements management starts with the customer’s image location collection (tasking) request, and continues with DigitalGlobe intelligently allocating its somewhat lean constellation of satellites and payloads against that task. The image is collected and delivered to you, the customer.
All AOIs considered.
Based on the image location (DigitalGlobe calls this an Area of Interest, or AOI), DigitalGlobe figures out which satellite is available and doesn’t have a payload full of other images. Then DigitalGlobe determines how urgent the customer’s need is for the image (does the customer want it quickly—how quickly versus others’ AOIs? Did another typhoon hit and affected customers in the region need images immediately?). DigitalGlobe will also determine the predicted weather in the AOI (clouds would be non-optimal—unless the customer wants clouds) to make sure the view is clear.
One tricky determination DigitalGlobe must do is figuring out the angle of the sun to the AOI. If the sun is too low on the horizon, the image might be too dark. The further north/south the AOI is, the more chances for that. The collection can be fully dependent on the season if the target is too far north or south. Images in the northern/southernmost latitudes can be taken, but in limited timeframes (windows). DigitalGlobe must also determine available satellite capability versus the appropriate tasking framework from which the collection was chosen. Not all of DigitalGlobe’s satellites have the same image sensor payload—resolutions can be different, some have more colors available than others, etc. (go here to see the differences if you’re interested).
It sounds like a lot, and it is. But if the company has trained people (and they probably do), decisions and determinations like those listed above become second-nature. There’s also probably some kind of software suite helping to determine sun elevation of AOIs and such, which is tremendously helpful in capable hands.
But you, as a customer, really don’t have to worry about all of those considerations. DigitalGlobe is going to figure all those things out once told what kind of product the customer needs. They just want you to know why an AOI collection may not happen, or might be delayed. All you need to do is make the collection request using what DigitalGlobe has labeled the Tasking Framework (page 5 of the brochure). They have a nice and easy table displaying four tasking options which customers can use to determine what kind of image is needed and what satellites (resolution/capability) are available.
What’s your priority?
“Priority” is not a satellite name, but this word is the cause of many uninformed customers’ consternation. Priority is exactly what it sounds like: if it’s a high priority AOI to the customer, and they’ve paid for it, it will likely be collected quickly.
What if your AOI collection is important but not urgent? Well, the collection could still occur, and I think that’s what DigitalGlobe means with the Assured Tasking option. It means they will guarantee the collection will happen, but only after they’ve figured out they can guarantee the collection and assign your AOI a particular collection window. And if that guarantee still doesn’t pan out (they cite weather as the big unknown), they give you free access to their imagery archive.
For emergencies, though, their “Single Shot” tasking option is the one to go with. DigitalGlobe dedicates and guarantees just one satellite, QuickBird, to the customer for AOI collection. They just say the AOI has to fit in a “single pass” of the satellite and sensor, which is specified as 13 kilometers wide by 360 kilometers long. And the AOI image collection will be attempted no matter if clouds are in the way or not. The urgency of the need justifies the second circumstance.
There you have it then—some nice and tidy AOI tasking packages. Notice there’s no actual price? Just understand, ultimately, the more money you pay, the greater the chance for you to get what you want. And the chances are good there is someone who is paying more for their AOIs to be collected than you, so patience and flexibility will help with this process.
DigitalGlobe doesn’t, at least in this document, seem to have a limitation on who can task their satellites, so if you’re really interested in seeing what they can do for you, try reading the brochure.
