In just a few hours, three taikonauts (space travelers) will launch from Earth to become the first crew to take residence in the Tiangong Space Station, whose main core module Tianhe (meaning “Harmony of the heavens”) was launched less than two months ago.

Commander Nie Haisheng, with operators Liu Boming and Tang Hongbo, will depart the Jiuquan Satellite Launch Center in Northern China on board the Shenzhou 12 on June 17 at 01:12 UTC. The crew will complete some of the station assembly as well as other crucial missions over a three-month stay, which is expected to also include two spacewalks. This will be China’s longest crewed mission in orbit to date and its first in almost five years since Taikonauts visited the predecessor of the current Tiangong Space Station.

“At present, the spacecraft and rockets are in good condition, and the launch site facilities and equipment are in good condition. The follow-up will carry out various pre-launch functional inspections and joint tests as planned,” said the press release, automatically translated from Chinese.

If everything goes according to plan, three more crewed missions will take place between now and the end of construction expected for 2022. This will be the second launch to the new space station after the Tianzhou 2 launch a week ago. Tianzhou 2 is part of China’s resupply cargo fleet. It is currently unknown if the cargo craft will be separated during the stay of the Shenzhou 12 crew or whether it will be separated in advance.

The full space station will be about one-fifth of the mass compared to the International Space Station and will orbit at a similar altitude of between 340 and 450 kilometers (210 and 280 miles). The ISS is kept at around 420 kilometers ( 260 miles). Two experiment modules will be launched next year. The first one will be Wentian (meaning Quest for Heavens) expected to launch around May–June 2022, followed about three months later by Mengtian (meaning Dreaming of Heavens).

The latest addition will be a separated telescope module called Xuntian (whose literal meaning is Touring the heavens).  The telescope is going to have a primary mirror 2 meters (6.6 foot) in diameter with a field of view 300 times larger than veteran space telescope Hubble. Over the ten-year primary mission, Xuntian is expected to image 40 percent of the Sky with its 2.5 gigapixel camera.

Shenzou 13 with the next crew of taikonauts is expected to fly there in October, with the following crews launching in late spring and late fall of 2022.