Spacekru

Spacekru are a survivor group of five Sky People and two Grounders, who were forced back into space to escape the Second Nuclear Apocalypse.

Going to Space
A small group, consisting of Clarke Griffin, Raven Reyes, Bellamy Blake, Monty Green, Harper McIntyre, John Murphy, Emori, and Echo, make a risky plan to survive Praimfaya in space. In Becca's lab, the group watches drone footage of the death wave moving through Polis, destroying everything in its path. They have ninety minutes to liftoff or the death wave will be too close. They successfully retrieve the oxygen generator and prepare the Vesta IV rocket, but Clarke gets delayed at the satellite tower. The other seven are forced to launch without her and hope that Clarke can successfully send the satellite signal to open the Ark's hangar door.

The seven arrive at the hangar door, but the Go-Sci Ring, the only remaining part of the Ark still in space, is still powered off. They wait but they only have ten minutes of oxygen left. Suddenly, the Ring's lights turn on – Clarke succeeded. The group embarks the Ring and manages to install an oxygen generator just in time. They mourn Clarke, believing she died for them, not knowing that her Nightblood allowed her to survive.

Six Years
In the aftermath of Praimfaya, the seven lived on the Go-Sci Ring waiting for a chance to return to the ground. They intended to stay there for five years, the time needed for the atmospheric radiation on Earth to drop to a survivable level, but due to lack of fuel they remained on the Ring for six years. They knew when going up that they lacked the fuel to come back to the ground, but they hoped they would solve the problem in the five years.

At first, it's all about survival. Monty tries to get the algae farm working but his first batch puts Murphy into a coma for almost a week. His later batches are more successful and he creates algae soup. They get the water reclamator working to recycle urine into drinking water.

The group, now calling themselves Spacekru, keep themselves occupied. The group established rules, breaking of which results in the offender doing chores. They train in combat, learn Trigedasleng and work on the Ring. Emori becomes Raven's apprentice, learning how to use and engineer various technologies. She assists Raven on spacewalks and learns to pilot the Vesta IV. Murphy gets frustrated since they don't have a way to return to the ground.

Their relationships also alter, with them coming closer together and considering each other family. It took Bellamy three years to forgive Echo for her past actions, specifically almost killing his sister, Octavia. However, at some point, the pair started a romantic relationship. Monty and Harper's relationship remains strong while Murphy and Emori's relationship falls apart. About 5.5 years after Praimfaya, Emori moves from the quarters she shared with Murphy to bunk with Raven instead.

Throughout, the group continues to monitor Earth. Emori makes regular radio calls, trying to tell everyone on the ground about the spot of green, even though Raven says it is waste of time due to atmospheric radiation blocking radio signals.

Six years and seven days after Praimfaya, they spot Eligius IV orbiting Earth and sending a transport ship to the ground. They use their rocket to get to Eligius IV and steal some fuel so they can also go to the ground. After realizing Eligius IV contains 283 cryosleeping prisoners, Raven and Murphy decide to stay on board, while the other five successfully descend to the ground.

Back on Earth
The five on the ground are almost immediately captured by a couple Eligius prisoners but are saved by Madi from whom they learn that Clarke survived.

As of "The Dark Year", the group is separated, with Bellamy, Monty, and Harper marching with Wonkru towards Shallow Valley and Echo, Raven, Murphy, and Emori already in the valley. At the end of "Damocles (Part 1)", in Shallow Valley, Echo, Murphy, and Emori reunite with Bellamy. But Raven held as hostage in the Gagarin and Monty and Harper at the wonkru tent in middle of desert.