WASHINGTON — A Soyuz rocket successfully launched 73 satellites, including spacecraft for four companies’ cubesat constellations, July 14.

The Soyuz-2.1a lifted off from the Baikonur Cosmodrome at 2:36 a.m. Eastern. The rocket deployed the primary payload, the Kanopus-V-IK remote sensing satellite, about an hour after launch, followed by 72 smallsat secondary payloads over the next seven hours.

“We had a great launch and all the satellites separated as planned,” Vsevolod Kryukovskiy, launch program director at Glavkosmos, said in an interview after the launch. “Everything is good.”

Among the secondary payloads were 48 Dove satellites from Planet, completing the company’s initial constellation of remote sensing cubesats. Mike Safyan, director of launch at Planet, said in a July 14 statement that all the satellites had separated from the rocket’s Fregat upper stage as planned, starting the process of positioning the satellites in their desired slots in sun-synchronous orbit.

“In total, the commissioning and orbital spacing will take a handful of months, but the Doves will begin imaging much sooner than that,” he said.

The secondary payloads included eight Lemur satellites for Spire, a company deploying a constellation for collecting GPS radio occultation and ship tracking data. The rocket also carried the first three CICERO GPS radio occultation satellites for GeoOptics and the first two Corvus-BC medium-resolution imaging cubesats for Astro Digital.

Other smallsats flying as secondary payloads included satellites from several nations, some built by Russian universities or for the Russian state space corporation Roscosmos. The Space Flight Laboratory at the University of Toronto built two NORsat smallsats for the Norwegian Space Center that carry ship tracking, communications and space science payloads.

The launch was the largest number of satellites flown on a single Russian rocket, and the second most on any single launch after the February launch of an Indian Polar Satellite Launch Vehicle carrying 104 satellites.

The launch was particularly complex in that it involved several maneuvers by the Fregat upper stage to deploy the satellites in three orbits. Kanopus-V-IK was released into an orbit at about 515 kilometers. The non-Dove smallsats were then released into a 600-kilometer orbit, followed by the Doves at 485 kilometers. After releasing all the satellites, the Fregat performed a deorbit maneuver.

Glavkosmos, which arranged the launch of the secondary payloads, is now working on a second such launch, scheduled for late this year from the Vostochny Cosmodrome in Russia’s Far East. That launch, Kryukovskiy said, will carry about 40 smallsats, but he said confidentiality agreements prevented him from disclosing the names of the customers at this time.

Kryukovskiy said this launch was a milestone for the company and the smallsat industry, which has often struggled to find rides for the growing number of spacecraft under development.

“Today is a big day for the smallsat community,” he said, recounting the speech he gave to his customers after the launch was declared a success. “Someone may say that you are secondary payloads, but for us you are primary customers!”