Ariane Places Two Satellites in Wrong Orbit

An Ariane 5 failed in a launch attempt of two satellites from Kourou, pad ELA 3, at 2158 UTC (2:58 p.m. PST) on July 12 possibly resulting in a US$1 billion loss. However, a propulsion failure in the rocket's upper stage resulted in a 592 km by 17,528 km (320 x 9464 nmi) orbit, inclined 2.9 degrees to the equator. Telemetry from the rocket indicated the vehicle had achieved a maximum velocity of just over 8 km/sec. The speed should have been about 9 km/sec at spacecraft deployment. The two satellites aboard the Ariane 5 were Artemis and BSAT-2B. Given the low orbit, it is not known if the spacecraft have enough fuel to reach their final destinations. The Artemis satellite has two reignitable engines while the Japanese satellite has only one engine which can be switched on only once. Even if the satellites can be maneuvered into the correct orbit the spacecraft will have significantly reduced life-spans. ArianeSpace is working to do all they can to recover the satellites and see what kind of operations are possible to recover the satellites and rectify this. Arianespace has launched an investigation into the mishap to determine what caused the problem.

BSAT 2B was for Japan-based B-SAT Corp. BSAT 2B is based on Orbital Sciences' STAR bus. The direct-to-home TV broadcasting spacecraft weighed 1 314 kg (2897 lbm) at launch. The satellite was to operate for 10 years in geostationary orbit at 110°E. BSAT 2B carried 4 Ku-band transponders to broadcast direct-to-home programming to homes and businesses in Japan.

Artemis (Advanced Data Relay and Technology Mission Satellite) will test and demonstrate  wide-coverage mobile satellite services, provide direct satellite-to-satellite communications, including a revolutionary laser link, and contribute to the European navigation system.

The 3105 kg (6843 lbm) satellite was built by Alenia Spazio for the European Space Agency (ESA). It was to have been located at 21.5°E. The demonstration spacecraft cost US$850 million (Euro 820 million).

Artemis, to have been located in geostationary orbit, was to demonstrate the relay of data from a LEO satellite. The Artemis data relay payload was to provide feeder links between Artemis and the ground and inter orbit links (IOLs) between Artemis and the spacecraft in LEO. The feeder links were to operate at 20/30 GHz, while the inter orbit links would operate at S-band (2 GHz), Ka-band (23/26 GHz) and optical frequencies. The feeder link, S-band and Ka-band payload elements jointly comprise the SKDR (S/Ka-band Data Relay) payload while the optical IOL payload element is called SILEX (Semiconductor Intersatellite Laser Experiment).

Artemis was equipped with one IOL antenna having a feed capable of operating at S-band and Ka-band. The IOL antenna was an offset parabolic reflector antenna with a 2.85 m (9.35 ft) aperture. The antenna was to be steered in the direction of the LEO spacecraft by rotating the reflector around its focal point by means of a pointing mechanism controlled by an on-board computer. The computer was to control the antenna pointing either in open or closed loop mode. In open loop mode the pointing direction is derived from a pointing table loaded by ground command into the computer. In closed loop mode the antenna was to acquire the LEO spacecraft using a pointing table, and then correcs the pointing direction and track the LEO spacecraft based on error signals derived from the higher order electromagnetic modes in the antenna feed and pre-processed by a track receiver. When the IOL operated in S-band, the antenna pointing was always to be performed in open loop, while for a Ka-band IOL the antenna could be pointed in open loop or in closed loop. To assist the LEO spacecraft in tracking Artemis an unmodulated wide beam beacon signal was to be broadcast by the latter at 23.540 GHz.

In addition to the data relay payload, Artemis carried a payload to support the communication of mobile users with fixed partners located anywhere in Europe, North Africa and the Near East. The LLM payload was fully compatible with the EMS payload already developed by ESA and flown onboard the Italsat-2 spacecraft, thereby providing full redundancy for its mission. The LLM payload was to receive the signals transmitted by the fixed users at Ku-band (14.2 GHz) and transmit them at L-band (1550 MHz) to the mobile users. This link is called the forward link. The return link was to establishe the connection from the mobile user at L-band (1650 MHz) to the spacecraft and at Ku-band (12.75 GHz) from the spacecraft to the fixed user. About 400 bi-directional user links could have been established simultaneously.

The 3-axis stabilized platform was designed to accommodate the payload elements of the Artemis mission, as well as, with minor modifications, those of other missions. The structural design utilized aluminum honeycomb material. The central cylinder is aluminum honeycomb skinned with carbon fiber. The primary structure provides the load path to the launch vehicle interface and comprises the central cylinder, main platform, propulsion platform and four shear panels. The major elements of the secondary structure are the north and south radiators, the east and west panels and the Earth-facing panel.

The satellite thermal control uses primarily passive techniques employing optical solar reflectors on radiator surfaces and multi-foil insulation blankets on the majority of the remaining external surface. The efficiency of the main radiators is enhanced by the use of heat pipes which are uni-directionally mounted under highly dissipative and/or sensitive equipment.

Power is generated by two identical solar array wings each of four panels made from CFRP (Carbon Fiber Reinforced Plastic) sandwich. Each wing is supported by a yoke, which is attached to the spacecraft via drive mechanisms located on the north and south faces. The array will be partially deployed in transfer orbit by cutting the Kevlar cables of the hold-down mechanism. Full deployment will be achieved on reaching geostationary orbit. The array was designed to deliver just under 3.000 kW of power during equinox after 10 years in orbit. Power storage is achieved with two identical 23-cell nickel-hydrogen batteries, each with a nominal capacity of 60 Ah. They are equipped to deliver just over 1.800 kW during eclipses of up to 72 minutes duration at a depth of discharge, with no cell failures, close to 75%. The spacecraft power is distributed via a single, fully regulated 42.5V bus.

Artemis uses a conventional bi-propellant system comprising a single 400 N Liquid Apogee Engine (LAE) and a set of 10 N Reaction Control Thrusters (RCT). The latter are configured into two identical redundant branches, each of eight thrusters. The Unified Propulsion System (UPS) will be used for apogee boost, longitude control, wheel off-loading, any re-location maneuvers and re-orbiting at the end of life. Inclination control will be performed by the Ion Propulsion Subsystem (IPS). The propellant is stored in two 700 liter Cassini-shaped tanks, one containing the mono-methyl hydrogen fuel and the other the nitrogen tetroxide oxidizer. The total bi-propellant to be loaded will be about 1538 kg (3390 lbm). The propellant tanks are pressurized by helium stored in three smaller spherical tanks. The IPS consists of two thruster assemblies, one mounted on each of the north and south faces. Each assembly comprises an Ion Thruster Alignment Mechanism upon which two redundant thrusters from different sources are mounted; a Radio-frequency Ion Thruster (RIT) from DASA and an Electro-bombardment Ion Thruster (EIT) from MMS. It will be used for inclination control throughout the satellite's lifetime. Each thruster has its own power supply and control equipment as well as its own flow control/propellant monitoring units. There is a common propellant supply and distribution assembly. The propellant used is xenon, of which 40 Kg is loaded on the satellite. In operation the system draws about 0.600 kW of power, which is mainly supplied directly from the solar array, augmented later in life by the batteries.

SPACEandTECH Digest is a weekly roundup of the latest industry news of interest to the space professional. SPACEandTECH Flash! is an internet push service offered by Andrews Space & Technology to bring the latest on orders, launches, and important breaking news to your desktop. SPACEandTECH Digest and SPACEandTECH Flash! are part of the Andrews Space & Technology www.spaceandtech.com website, a website designed to serve the information needs of the space industry.

If you would like to subscribe to the SPACEandTECH Flash! (currently a free service), contact the www.spaceandtech.com Editor-in-Chief, Joe Hopkins, at editor@spaceandtech.com