The highly anticipated return to flight for Orbital ATK’s Antares rocket went off, essentially without a hitch on Monday night, as after just a five-minute delay, the rocket blasted off from NASA’s Wallops Flight Facility in coastal Virginia. Bound for the International Space Station, the rocket lofted a Cygnus spacecraft, packed with over 5,000 pounds of research and supplies.

See also: Orbital ATK’s Cygnus Spacecraft Will Soar to the Space Station on October 17

Aside from the delay, due to a minor issue with one of the Antares engines, which was resolved in time to launch at 7:45 p.m. EST, the entire ordeal went smoothly. And after a little more than 10 minutes,Cygnus was safely in orbit — which must have been a relief for NASA.

The last time Antares flew was nearly two years ago, and things didn’t exactly go as planned. During the previous launch, a wayward sailboat drifted into the rocket’s path downrange, causing a 24-hour delay. The next attempt ended in a fiery explosion that rocked Virginia’s Eastern Coast. Occurring just seconds after launch, the mishap destroyed the vehicle and caused $15 million in damages to the launch pad.

Immediately following the incident, both NASA and Orbital launched their own investigations into the anomaly to figure out what happened. It wasn’t long before Orbital identified the culprit: one of the Antares’s main engines.

The Orbital ATK Antares rocket exploded moments after launch on October 28, 2014.
The Orbital ATK Antares rocket exploded moments after launch on October 28, 2014.

At that time, Antares was powered by two AJ26 engines that were originally built by the Soviets in the 1960s, and subsequently refurbished by Aerojet Rocketdyne — an American manufacturer. Careful analysis showed that one of the two AJ26 engines had a defective turbopump, which helps pump fuel into the engine.

The defect could have occurred when the turbopump was originally manufactured decades ago, or when Aerojet refurbished it, or as a result of debris from somewhere else in the vehicle. No one can say for sure, but both NASA and Orbital agreed on one thing: the engines had to go.

Replacing a rocket’s engines is a complicated and time-consuming process. Thanks to the grit and hard work of countless individuals, Antares is back, and sporting new RD-181 engines (also manufactured in Russia).

The Orbital ATK Antares rocket is rolled out of the integration facility and to the launch pad on October 13, 2016.
The Orbital ATK Antares rocket is rolled out of the integration facility and to the launch pad on October 13, 2016.

In addition to replacing the engines, Orbital also had to repair damages to the launch site, which took a year to complete. The list of repairs included replacing four lightning towers surrounding the launch pad, debris removal, and environmental cleanup.

While crews in Virginia worked to restore the launch site, Orbital still had to fulfill its commitment to NASA, ensuring the ISS is well-stocked. To hold up their end of the bargain, Orbital partnered with the United Launch Alliance, purchasing two rides on an Atlas V rocket — one that launched in December 2015, and one in March 2016 — delivering cargo to the space station.

In May of this year, Orbital showcased the newly renovated launch pad, and put the Antares rocket through its biggest test since the engine swap out: a static fire test. During this crucial pre-flight test, the rocket engines are fired for a few seconds, while the vehicle is strapped down, ensuring it won’t take flight. Orbital said the test went well and Antares is ready to fly.

The Orbital ATK Antares rocket, with the Cygnus spacecraft onboard, stands on launch pad, waiting to take flight.
The Orbital ATK Antares rocket, with the Cygnus spacecraft onboard, stands on launch pad, waiting to take flight. 

With SpaceX grounded for the time being, due to a Falcon 9 rocket exploding on the pad in September, there was a lot riding on this mission.

Orbital hopes to play a pivotal role in the ever-expanding commercial space market. The company is looking beyond low-Earth orbit, eyeing the Moon and even Mars. Tonight’s launch goes a long way to securing their future.

Photos via NASA/Joel Kowsky, NASA/Bill Ingalls, Getty Images / Bill Ingalls/NASA, NASA