Minotaur launches 10 satellites for Planet

WASHINGTON — An Orbital ATK Minotaur-C rocket successfully launched two sets of satellites for Earth observation company Planet Oct. 31 in what was effectively the return to flight of a vehicle that failed in its two previous missions.

The Minotaur-C lifted off from Space Launch Complex 576E at Vandenberg Air Force Base in California on schedule at 5:37 p.m. Eastern. The rocket deployed its payload of six SkySat spacecraft and four Dove cubesats between 13 and 19 minutes after liftoff, but a lack of real-time telemetry meant that confirmation of the successful launch did not come until more than two hours after liftoff, once Planet made contact with the satellites via its ground stations.

The launch was the first for the version of the Minotaur called the Minotaur-C, which in fact is the company’s earlier Taurus rocket with modest upgrades. The previous two Taurus launches, of NASA’s Orbiting Carbon Observatory in 2009 and its Glory satellite in 2011, both ended in failure when the Taurus’ payload fairing failed to separate.

The Minotaur-C features a new payload fairing based on the design used on other versions of the Minotaur rocket, as well as updated avionics. The “C” in its name reflects the use of commercially procured rocket motors, allowing the vehicle to launch commercial as well as government payloads. Other Minotaur rockets use excess ICBM motors for some of their stages, restricting their use under current national space policy to government-sponsored payloads.

The primary payloads for the launch were six SkySat satellites, built by Space Systems Loral and each weighing about 100 kilograms. Planet obtained the satellites as part of its acquisition of Terra Bella, formerly Skybox Imaging, from Google earlier this year.

Each SkySat can take images at resolution as sharp as 86 centimeters. The six launched on this mission join seven others previously placed in orbit, including four on a Vega mission in 2016.

Also on board the Minotaur-C were four Dove cubesats, built by Planet. These satellites will join a fleet of more than 150 operational Dove satellites that provide medium-resolution imagery.

The launch was the first time Planet was the primary customer for a launch, having relied on secondary payload accommodations for all its previous launches. “Planet is in the driver’s seat with respect to launch date and defining orbital parameters,” said Mike Safyan, senior director for launch and global ground stations at Planet, in a September blog post.

That gave the company the flexibility to choose this particular orbit, a sun-synchronous orbit (SSO) that crosses the Equator at 1:30 p.m. local time. “We intentionally chose an afternoon orbit to complement our existing morning-SSO fleet,” he wrote. “With morning and afternoon constellations working in tandem, we have the ability to monitor areas of interest twice daily in both medium- and high-resolution, and we can capture different types of activities that happen at different times of the day.”

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