The Endeavour astronauts, aboard the orbiting space station complex, are close to accomplishing the primary objective of their mission, NASA said.

Early Thursday, the crew successfully lifted a cosmic ray detector from Endeavour, which was set to be installed on the International Space Station (ISS). The Alpha Magnetic Spectrometer, worth $2 billion, was delivered by the space shuttle.

The instrument consists of a 3-foot magnet at its core and will be used to study the invisible part of the universe. It will search for both dark matter and antimatter from the space station.

Meanwhile, back at the mission control, engineers are examining different areas on Endeavour’s belly which yielded damages. Thermal tiles were scratched and notched during Monday’s liftoff.

NASA, in a report, said it wants to make sure the shuttle is in a safe condition to come home in two weeks.

NASA International Space Station NASA