UPDATE: ULA’s launch of NROL-37 is scrubbed for today. As expected, the weather didn’t cooperate. Next launch window starts Saturday at 1:51 pm ET.

Original story follows

Today’s United Launch Alliance spy satellite launch isn’t as unusual as you might think. Just this year, ULA will send five clandestine satellites into orbit for the National Reconnaissance Office (NRO). But today’s launch will be more unique than the other four.

Here’s what we know

NROL-37 will sit atop a Delta IV-Heavy rocket at launch. The type of rocket hints at where today’s spy satellite launch is heading – geosynchronous transfer orbit (GTO). Here’s what a regular Delta IV Medium rocket looks like (there are several different configurations, but they don’t differ all that much).

delta iv medium diagram

Now, here’s the Delta IV Heavy rocket.

delta iv heavy diagram

The obvious difference is the Heavy variation sports two additional boosters.

Both rockets can place payloads in GTO, but the size of the payload varies big time. The Delta IV Medium can place a 9,280-pound payload in GTO. The Delta IV Heavy increases that to 30,440 pounds. The low-Earth orbit (LEO) payloads sit at 20,250 pounds and 62,540 pounds, respectively.

Note: The payload numbers vary on ULA’s website. A separate page shows payload performance for LEO at 49,740 pounds and GTO at 28,620 pounds.

Either the National Reconnaissance Orbit satellite is extremely heavy, or it’s going into GTO. (It’s going to GTO)

delta iv heavy rocket

What will NROL-37 do? All we have is the mission description via ULA: The mission will be launched for National Reconnaissance Office in support of national defense. Translation? It’s a spy satellite built to do spy things.

A geosynchronous orbit is perfect for an intelligence gathering satellite. Because the orbit is designed to match Earth’s rotation, NROL-37 will always be above the same point on Earth. This orbit is common in other satellites too including weather and communications.

Watch it live. At 1:59 pm ET, the Delta IV Heavy will lift off from Cape Canaveral Air Force Station, Space Launch Complex 37B. That’s the plan anyways. The launch window is from 1:59 – 6:35 pm ET. But the weather might not cooperate. ULA says there’s a 40% chance of favorable weather for today’s launch.

ULA’s webcast starts 20 minutes before launch. Check it out here.

See a rocket launch in person. Unfortunately, the LC-39 Observation Gantry is sold-out for today’s launch. But, if you’re going to be near Cape Canaveral on June 14, swing by and watch SpaceX’s Falcon 9 rocket send two communications satellites into space.

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