WorldView-4

The latest DigitalGlobe satellite, WorldView-4, is due to be launched in less than two weeks’ time and enhance their capacity to collect the world’s highest resolution commercial satellite imagery.

The satellite is currently located at Vandenberg Air Force Vase ahead of its launch on the Atlas V launch vehicle on the 15 September 2016. So what do we know about this addition to the WorldView family? An article published by DG this week gives us a great insight, which I have summarised below.

So how big is it?

Compared to other satellites, it’s big – ‘about the size of a Chevy suburban’ or Land Rover in the UK. They state that despite the size of hardware dramatically decreasing in recent years, they could not reduce the size of the telescope without degrading the resolution of the satellite imagery. They aim to provide the highest resolution imagery, and therefore some things cannot be reduced in size… yet! The graphic below shows just how big it is!

WorldView-4

WorldView-4

 

What Imagery will be obtained?

The satellite will be able to obtain imagery with a spatial resolution of 31cm, similar to the WorldView-3 capabilities. Each day this satellite collects more than 680,000 km2 of imagery every day, and will operate 365 days a year, 24/7.
The 31cm imagery will be in the panchromatic band and the multispectral information will be acquired at a resolution of 1.24m: Pan (450-800nm), Red (655-690nm), Green (510-580nm), Blue (450-510nm) and NIR (780-920nm).

How does it know what it’s looking at?

Essentially, on-board GPS units and ‘star-trackers’ (that look upwards and understand its position), and this lets us know where it is. This also ensures that the imagery is very accurate, less than 3m in fact.

Can the satellite ‘turn its head’?

Yes – it has the capability to look forwards, backwards, left or right to get the image that is needed because of the inbuilt ‘control moment gyros’. This allows it to capture imagery at the two angles in the image below – retaining its impressive quality.

WorldView-4 Las Vegas View

WorldView-4 Las Vegas View

 

How are the images returned to Earth?

Radio is the answer! Radio waves send the data earthbound to ‘remote ground terminals’ which then send the data to DG. Simple eh!

What’s the revisit time?

The entire DG constellation now means it’s possible to image any location on earth three or four times a day. This is important so that big events can be closely monitored. The revisit time of this satellite alone is < 3 days.

WorldView-4 therefore offers huge potential for satellite imagery users and without doubt ensures DG stays at the forefront of the ‘high resolution’ imagery market. That pretty much covers it for the important stuff, for further information please visit: DigitalGlobe and eoPortal.

 

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