Chinese Long March 4B Launch Failure traced back to Upper Stage Malfunction
December 12, 2013
While the Long March 4B failure is under investigation, launches of the CZ-4B and similar vehicles are on hold. Long March 4B had one more launch scheduled for 2013 to deliver the Gaofen-2 remote sensing satellite to orbit. At least four Long March 4B launches were planned for 2014.
CBERS-3 Launch atop Chinese Long March 4B ends in Failure
CBERS-1 carried three remote sensing instruments for Earth Observations. Instruments installed on the vehicle were the Wide Field Imager Camera, a Medium Resolution Camera and an Infrared Multispectral Scanner Camera. The spacecraft operated until August 2003.
In October 2003, CBERS-2 launched atop a Long March 4B. The satellite was identical to CBERS-1 and operated until late 2007 when it was retired because the next satellite became operational. CBERS-2B launched on September 19, 2007. The spacecraft was similar to the first two CBERS satellites but carried an additional instrument, a High Resolution Panchromatic Camera. The satellite suffered an electrical failure in late 2010 and could no longer be operated.
Taking the next step in the CBERS program, China and Brazil started the development of advanced instruments for flight aboard the CBERS-3 and 4 satellites.
Originally, CBERS-3 was planned to be launched four years ago to minimize the gap in between CBERS satellites, but problems during instrument development and satellite testing led to a number of delays and the launch ended up planned for December 2012.
During final testing of the satellite, however, electrical problems related to DC-to-DC voltage converters were found, pushing the launch into 2013 as the converters had to be replaced and the satellite re-tested. China, having a number of operational remote sensing satellites in orbit, was not under pressure to launch the satellite, but there was strong political pressure in Brazil because the country was relying on commercial satellite imagery that comes with a high price tag.
Finally, in October 2013, all tests on the satellite were complete and CBERS-3 was transported to the launch site for final launch preparations. On the Brazilian side, some concern remained that the Brazilian portion of the satellite could fail shortly after launch due to the problems teams had before the mission. On November 27, the Satellite Readiness Review was performed and the payload encapsulated in the protective CZ-4B fairing was transported to the launch pad. After a long way, CBERS-3 had reached the launch pad and was declared ready for liftoff.
MUXCam, the Multispectral Camera, is a pushbroom-type instrument with a field of view of 4.4 degrees and a focal length of 506 millimeters. The optical system (entrance mirror, a window, a moving lens & 11 fixed lenses) along with the focal plane is facilitated within the RBNA system while the RBNB system includes thermal control electronics, the focus adjustment mechanism and the instrument calibration system. The RBNC system generates CCD reading clock signals, and includes output processing units and encoding systems that handle the payload data. MUXCam uses a 4-line array detector with 6000 pixels per line being 13 micrometers in size. The instrument covers four spectral bands: 450-520nm (blue), 520-590nm (green), 630-690nm (red) and 770-890nm (near infrared). MUXCam achieves a ground resolution of 20 meters covering a swath of 120 Kilometers.
Data provided by the individual instruments goes through onboard processing by the Data Collection System ahead of downlink to the ground. S-Band communications are used to downlink housekeeping telemetry and uplink spacecraft commands. A high-speed X-Band link of 305Mbit/s is used to downlink payload data that is stored in a 274 Gbit recorder.
CBERS-3 was targeting an operational Sun-Synchronous Orbit of 778 Kilometers at an inclination of 98.5 degrees with a Local Time of Descending Node of 10:30. The satellite was expected to operate for three years.
The third stage supports burns of up to 359 seconds to inject the payloads into their desired orbit. Long March 4B is topped by a 3.35-meter payload fairing that is 8.48 meters in length.