Chang’e 3 soars to the Moon, following impressive night-time launch

Chang'e 3 seen here after separation from the rocket's upper stage, following the Trans-Lunar Insertion Burn that put it on a course for the Moon. Image Credit: CCTV.

SpaceFlight Insider

Staying true to the nature of its mythological namesake, the Moon-bound Chinese lander Chang’e 3 thundered into the skies at 17:30 GMT today above the Xichang Satellite Launch Center located in mainland China atop a Long March 3B launch vehicle. Chang’e 3’s historic launch, which was carried live by China’s state television, is of double significance. It represents China’s first attempt at making a controlled landing on the Moon, and also marks the first lunar landing mission attempted by any nation since the former Soviet Union’s Luna 24 mission in 1976.

Launch preparations continued without incident during this weekend at the launch site. The launch itself occurred on time, at 17:30 GMT December 1 (Dec. 2 at 1:30 p.m. EST), right at the opening of the launch window. The Long March 3B, China’s current heavy-duty launch vehicle, lit up the night sky and left the launch tower in an impressive display of technical sophistication, following a southeast trajectory over the Pacific Ocean.

During the first three minutes of launch, Long March’s 3B first stage, aided by four strap-on liquid fuel boosters, guided Chang’e 3 through the initial phases of the ascent. Having depleted their propellant, the strap-on boosters separated from the vehicle at T+127 seconds after launch, with the first stage following 20 seconds later. At this point, the second stage’s main engines took over for a 3-minute burn to guide the spacecraft out of the Earth’s atmosphere.

With the second stage having achieved its goal at approximately T+5.5 minutes after launch, the third stage ignited for a 4-minute burn before shutting down, delivering Chang’e 3 to a Low Parking Orbit (LPO) 200 km above the Earth. The flight profile required two burns of the third stage engine. The first burn would put the spacecraft into a LPO in order for it to gain altitude, and be at the right coordinates for the critical Trans-Lunar Insertion (TLI) burn. Then, it reignited, giving the needed thrust for the spacecraft to escape orbit and achieve TLI. This second burn happened precisely on time at T+14 minutes, which will allow the spacecraft to rendezvous with the Moon five days from now. With the crucial TLI burn complete exactly 19 minutes into the flight, Chang’e 3 finally separated from the rocket’s third stage, ready to begin its cislunar coast.

With Chang’e 3’s instruments checked and solar panels deployed, the spacecraft will spend its next few days speeding towards the Moon, where it is planned to arrive on December 5.

Before approaching the Moon, Chang’e will undergo two Trajectory Correction Manuevers, or TCMs, which will allow it to enter into the proper lunar orbit altitude prior to landing. The first of these TCMs will take place tomorrow, December 2, and the second will transpire one day prior to reaching lunar orbit, on December 4.

On the following day, December 5, the spacecraft will have reached the vicinity of the Moon, it will execute a do-or-die Lunar Insertion Burn (or LIB), in order to decelerate enough to be caught by the Moon’s gravity. The LIB is one of the most crucial aspects of the mission. Any failure during this phase will result on Chang’e flying past the Moon at a high rate of speed, bringing a premature end to the mission.

Chang’e 3 will then spend the next 10 days going through an instrument commissioning phase to ensure everything is nominal prior to landing on December 15 at the Moon’s Sinus Iridum, or “Bay of Rainbows.” Once there, the lander will commence a 90-day mission of lunar exploration. It will deploy a small rover called “Yutu” that will investigate the abundance of lunar minerals and resources on the lunar surface.

Stay tuned to Spaceflight Insider for continued updates concerning this historic mission.

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