COVER STORY

An enduring partnership

R. RAMACHANDRAN

AT a recent quiz competition at the Indian Space Research Organisation in Bangalore, one of the posers to the young engineers and scientists was: "State the next number in the sequence 3, 24, 51, 58, 81, 97, ..." The answer - 117 - had the participants stumped: the seemingly complex arithmetic series was in fact the sequence of flight numbers of the Ariane launchers that have deployed ISRO's satellites in space, beginning with the experimental Ariane Passenger Payload Experiment (APPLE) in June 1981. Arianespace, the company promoted by the French Government as the launch service provider for the European Space Agency (EAS), was established barely a year earlier and one of the first qualification launches of the ESA's first launch vehicle Ariane 1 carried the Indian spacecraft.

On April 3, this long-standing relationship between the two organisations crossed another milestone when Arianespace's Launch No. 117 injected the 2.5-tonne multipurpose INSAT-2E, the last of ISRO's second-generation INSAT series, into the Geostationary Transfer Orbit (GTO). This was the seventh launch by Arainespace for ISRO. The next one is due in September when the ESA's newly qualified workhorse, Ariane 5, will carry the first of ISRO's next INSAT series, INSAT-3B, into space, in its fifth flight and only its second commercial launch.

Since 1981, and until INSAT-2E's launch, Arianespace has launched five other Indian spacecraft: INSAT-1C in July 1988 (on Flight 24), INSAT-2A in July 1992 (Flight 51), INSAT-2B in July 1993 (Flight 58), INSAT-2C in December 1995 (Flight 81) and INSAT-2D in June 1997 (Flight 97).

The early INSAT launches were aboard U.S. launchers: INSAT-1A on the two-stage McDonnel Douglas' Delta I Launcher 3910 (April 1982), 1B on the STS-8 launch of the National Aeronautics and Space Administration's (NASA) Shuttle Transportation System (STS) Challenger (August 1983), and 1D on the three-stage Delta II launcher 4925 (June 1990); however, the efficiency and the success rate of Ariane launches, coupled with the smooth working relationship between ISRO and Arianespace seem to have led ISRO to repose greater faith in the European launcher for its INSAT-2 series.

In fact, according to the original document on the INSAT system, the INSAT-1 series of satellites were specifically designed for launch either with the two-stage Delta 3910/3920 launchers or the space shuttle. The Challenger disaster in 1986 forced ISRO to look for an alternative, and the new Ariane launcher system, with its flexible fairing (the satellite bay), could easily accommodate INSAT-1C's launch in July 1988. Prior commitment to the launch contractor McDonnel Douglas, however, led to INSAT-1D being launched aboard the newly configured Delta II; there was a mishap at the launch site when a crane hook fell on the satellite and damaged its C-band antenna. After this ISRO has stuck to Ariane.

The Ariane 42P launch vehicle. ISRO and Arianespace have a smooth working relationship, which has been strengthened by the efficiency and success rate of Ariane launches.

The launch vehicle for Flight V117 was Ariane 42P, one of the many configurations of the launcher Ariane 4 (2P denotes the two solid booster stages). The bulk of Ariane's launches have been dual payloads, and INSAT-2E was originally scheduled to be launched in September 1998 along with a European satellite, Eutelsat. However, the loss of INSAT-2D owing to a random short circuit in the spacecraft's main bus and the consequent loss of on-board power and earth lock called for modifications in the overall system design of INSAT-2E, leading to a six-month delay.

In the light of its long-standing relationship with ISRO, Arianespace offered to have a dedicated launch for INSAT-2E for $68 million, the launch cost to which it had committed itself earlier even though it would have entailed a small loss to Arianespace. The gesture is, of course, not without a long-term business interest: the INSAT-3 series is coming up; INSAT-3B is already booked on Ariane, and Arianespace would like to ensure that ISRO continues to use its services for 3A, 3D and 3E.

Although the latter satellites of the INSAT-3 series are being designed keeping in mind the launch capability of the Geosynchronous Satellite Launch Vehicle (GSLV) which is under development, the entire INSAT 3 series will in all likelihood have to go on procured launches given the delays in the GSLV programme owing to internal and external factors. And with the established success rate and reliability of Ariane, the launcher-customer relationship between Arianespace and ISRO is likely to continue into the next millennium.

The collaboration entered a new phase in 1998 when Arianespace and ISRO'S marketing arm Antrix Corporation signed an agreement for the joint marketing of ISRO's Polar Satellite Launch Vehicle (PSLV) and Arianespace's Ariane 5 to launch auxiliary payloads in the weight class of up to 100 kg, termed as microsatellites. Under this cooperative agreement, the two agencies formed a Committee for Auxiliary Payload Policy Execution (CAPE) in order to encourage and enlarge the launch opportunities for small satellites.

Both Antrix and Arianespace will establish a common User's Manual for auxiliary payloads that will be compatible with both PSLV and Ariane 5. This will facilitate the ability of users to launch their small satellites either with Ariane 5's ASAP (Ariane Structure for Auxiliary Payloads) system or the Specific Auxiliary Payload Structure (SAPS) developed for the PSLV. The third developmental launch of the PSLV is scheduled for mid-May; it will carry two microsatellites, KITSAT (of South Korea) and the German TUBSAT, as auxiliary payloads besides Oceansat (IRS-P4), the one-tonne class Indian remote-sensing satellite for ocean studies. A top Arianespace official is expected to witness the launch.

The potential of the PSLV to launch replacement satellites for low earth orbiting (LEO) constellation communication systems like Iridium, Globalstar, ICO and so on is also under discussion between the two agencies. A capability to launch satellites at desired inclined orbits would be required for this purpose. Indeed, in the emerging scenario in the launch service market, with increasing demand for launch capacity on the one hand and criticality of time-frame for global telecommunication systems based on LEO satellite constellations on the other, such joint services are likely to be the order of the day. Already, a joint Russian-European arrangement called Starsem has been formed with Arianespace as its launch contractor which will offer services of the Russian Soyuz launcher and the Ariane. A cluster of six Globalstar satellites were recently launched by Arianespace aboard Soyuz.