The world’s most advanced high-resolution satellite, WorldView-3, will launch tomorrow – operated by DigitalGlobe, our primary provider of high-res imagery. With 31 centimeter (12 inch) resolution, it will set a new record for image clarity from space. That’s just one of several groundbreaking features.
The 31 cm pixels will provide sharpness that’s only available today in aerial imagery. As we demonstrated when DigitalGlobe was relicensed for 40 cm resolution, a decrease in the linear pixel size means an exponential increase in 2D resolution. At 50 cm, a given square meter is covered by four pixels, while at 31 cm, it’s divided into a little more than nine. We knew the math, but we wanted to see what it meant, so this morning the satellite team got out the scissors and tape and made some pixels:
Left: WorldView-3–size pixels, at 31 cm. Right: today’s typical high-res pixels, at 50 cm. This is the moment when our remote sensing specialist, Camilla, and our chief scientist, Bruno, noticed that he can just about fit behind one of the 50 cm pixels.
Spatial resolution lets you see things, but it’s spectral resolution that helps you understand them. Like most imaging satellites WorldView-3 will have a panchromatic band plus red, green, and blue to collect true-color imagery. But it goes much further. For distinguishing vegetation differences, it has a red edge band (on the border between red and near infrared), two near infrared bands, and a yellow band that’s good at picking up where plants are dying or ripening. (Think of a wheat farm: if a farmer can tell that the center of a certain field is reaching the harvest stage sooner than expected, that could save a lot of wasted resources.)
For geology and ecology, there are six separate shortwave infrared bands. Subtle differences between these bands will expose otherwise invisible variations in surface composition and moisture, vegetation, and even building materials. For marine applications, there’s a coastal band in the deep blue. It’ll help with atmospheric correction, but most of that will be done by a separate calibration instrument called CAVIS, for Clouds, Aerosols, Water Vapor, Ice, and Snow. These are five of the hardest things for satellites to deal with, and addressing them head-on with a dedicated sensor system is a bold move.
Data volume and accuracy
When a satellite carries so much interesting hardware, the catch is often that it returns very little imagery; but from its planned orbit, WorldView-3 can collect roughly the area of Texas every day. That combination of quantity and quality is unprecedented. To handle the space-to-ground transfer of so much data, the satellite will use an X-band radio link more than a hundred times faster than a home internet connection.
One detail that’s particularly important to our work - WorldView-3 will know where it’s pointing much better than most satellites do. A very slight change in look angle translates to a huge on-the-ground distance, so most raw satellite imagery could be anywhere in a surprisingly wide radius until it’s calibrated against known landmarks. But WorldView-3 will have an exceptionally good “sense of balance”. It’s expected to be able to judge its own look angle well enough to place imagery within 3.5 meters (at 90% confidence) before any on-the-ground calibration.
WorldView-3 is bigger than a Volkswagen van (even without its solar panels), and will weigh almost 3 tons when fully fueled at launch. It takes an Atlas V 401 rocket to put it in orbit. Once it’s there, a satellite so complex takes several months to test and calibrate before it starts producing commercial imagery. We’ll be waiting impatiently.
Join us watching the ground-to-orbit webcast on Wednesday morning. The launch window opens at 11:30 a.m. PDT (2:30 p.m. EDT, 6:30 p.m. UTC) and lasts for a quarter of an hour. Remember to tune in a bit early to catch the countdown. One warning: space launches depend on unpredictable factors like weather and ground safety, so there’s a always chance it’ll have to move back a day. I’ll update this post if it’s delayed.