In its tenth flight conducted from Satish Dhawan Space Centre (SDSC) SHAR, Sriharikota, today (January 10, 2007), ISRO’s Polar Satellite Launch Vehicle, PSLV-C7, successfully launched four satellites — India’s CARTOSAT-2 and Space capsule Recovery Experiment (SRE-1), Indonesia’s LAPAN-TUBSAT and Argentina’s PEHUENSAT-1 into a 635 km high polar orbit. For the first time, a Dual Launch Adopter (DLA) was used in PSLV to accommodate two primary satellites in tandem.

After the final count down, PSLV-C7 lifted off from the first launch pad at SDSC SHAR, at 9.23 am with the ignition of the core first stage and four of the six strap-on motors. The remaining two strap-on motors were ignited at 25 sec after lift-off. The important flight events included the separation of the ground-lit strap-on motors, separation of air-lit strap-on motors and the first stage, ignition of the second stage, separation of the heatshield at about 121 km altitude after the vehicle had cleared the dense atmosphere, second stage separation, third stage ignition, third stage separation, fourth stage ignition and fourth stage cut-off.

The 680 kg main payload, CARTOSAT-2, mounted over DLA, was the first satellite to be injected into orbit at 981.3 sec after lift-off at an altitude of 639 km. About 45 sec later, DLA with the 6 kg PEHUENSAT-1 mounted on it, was separated. 120 sec later, the 550 kg Space capsule Recovery Experiment (SRE-1) mounted inside DLA was separated and finally, 190 sec later, the 56 kg LAPAN-TUBSAT, mounted on the equipment bay of PSLV fourth stage was separated. The four satellites have been placed in a polar orbit at an altitude of 637 km with an inclination of 97.9 deg with respect to the equator. The initial signals indicate their normal health.

PSLV is the workhorse launch vehicle of the Indian Space Research Organisation (ISRO) with nine consecutively successful flights so far. Since its first successful launch in 1994, PSLV has launched seven Indian remote sensing satellites, an amateur radio satellite, HAMSAT, and four small satellites for foreign customers into 550-800 km high polar SSOs. Besides, it has also launched India’s exclusive meteorological satellite, Kalpana-1, into Geosynchronous Transfer Orbit (GTO). PSLV will also be used to launch India’s first spacecraft mission to moon, Chandrayaan-1, during 2008.

The 44 m tall PSLV has a lift-off mass of 295 tonne. It is a four-stage launch vehicle with the first and the third stages as well as the six strap-ons surrounding the first stage using HTPB based solid propellant. PSLV’s first stage is one of the largest solid propellant boosters in the world. Its second and fourth stages use liquid propellants. PSLV’s bulbous payload fairing has a diameter of 3.2 metre. The vehicle has S-band telemetry and C-band transponder systems for monitoring its health and flight status. It also has sophisticated auxiliary systems like stage and payload fairing separation systems. PSLV was originally designed to put 1,000 kg class of India’s remote sensing satellites into a 900 km polar SSO. The payload capability of PSLV has been successively enhanced and in today’s flight, PSLV-C7, it launched four payloads, in all weighing 1292 kg in addition to the DLA. Some of the modifications incorporated in PSLV-C7 compared to the previous flight, PSLV-C6, are:

  • Use of Dual Launch Adopter
  • Reduction of propellant from 2.5 tonne to 2 tonne in the fourth liquid propellant stage, PS4
  • Altitude based Day of Launch wind biased steering programme during Open Loop Guidance

CARTOSAT-2, the twelfth in the Indian Remote Sensing (IRS) satellite series, is an advanced remote sensing satellite capable of providing scene-specific spot imagery. It will join the other six IRS satellites which are in service — IRS-1C, IRS-1D, OCEANSAT-1, Technology Experimental Satellite (TES), RESOURCESAT-1 and CARTOSAT-1. It carries a Panchromatic camera (PAN) to provide imageries with a spatial resolution of better than one metre and a swath of 9.6 km. The satellite can be steered up to 45 deg along as well as across the track. The data from the satellite will be used for cartographic applications at cadastral level, urban and rural infrastructure development and management, as well as applications in Land Information System (LIS) and Geographical Information System (GIS).

Soon after its separation from the DLA, the two solar arrays of CARTOSAT-2 were automatically deployed to generate the electrical power for the satellite. The satellite health is being continuously monitored from the Spacecraft Control Centre of ISTRAC at Bangalore with the help of its network of stations at Bangalore, Lucknow, Mauritius, Bearslake in Russia, Biak in Indonesia, as well as support from Svalbard ground station in Sweden for the initial phase of the CARTOSAT-2 mission. Further operations on the satellite like orbit trimming, checking out the various subsystems and, finally, switching on the cameras will be carried out in the coming days.

With ISRO Satellite Centre (ISAC), Bangalore, as the lead Centre, CARTOSAT-2 was realised with major contributions from Space Applications Centre (SAC), Ahmedabad, LPSC at Bangalore, and IISU, Thiruvananthapuram. ISTRAC is responsible for initial and in-orbit operation of CARTOSAT-2. The National Remote Sensing Agency (NRSA), Hyderabad receives and processes the data from CARTOSAT-2.

Space capsule Recovery Experiment (SRE-1): Space capsule Recovery Experiment (SRE-1), developed by ISRO’s VSSC and ISAC, is a 550 kg capsule, intended to demonstrate the technology of an orbiting platform for performing experiments in microgravity conditions. After the completion of the experiments, the capsule will de-orbited after a few days and recovered. SRE-1 mission will provide valuable experience in such important fields like navigation, guidance and control during the re-entry phase, hypersonic aero-thermodynamics facilitating the development of reusable thermal protection system (TPS), recovery through deceleration and floatation besides acquisition of basic technology for reusable launch vehicles.

SRE-1 carries two experiments, an Isothermal Heating Furnace [IHF] and a Biomimetic (Biomineralisation of Inorganic materials) experiment. IHF will be operated to perform metallurgical experiments while Biomimetic experiment will be operated to perform Biomimetic synthesis. SRE-1 comprises aero-thermo structure, spacecraft platform, deceleration and floatation system besides the micro-gravity payloads. It has a sphere-cone-flare configuration with a spherical nose of about 0.5 m radius, base diameter of 2 m and 1.6 m height. The capsule is made of mild steel. The parachute, pyro devices, avionics packages of triggering unit and sequencer, telemetry and tracking system and sensors for measurement of system performance parameters are placed inside SRE capsule.

Two days before de-orbiting, SRE-1 will be placed in a Repetitive Elliptical Orbit. Subsequently, it will be reoriented and deboost rocket is fired to make it reenter the earth’s atmosphere. Close loop guidance system is employed during deboost and coasting phases leading to its recovery. On re-entry, after initial aerodynamic braking, a parachute system will reduce the touch down velocity. SRE-1 will splashdown in the Bay of Bengal, east of Sriharikota coast. A floatation system will keep SRE afloat and enables its recovery.

SRE-1 is being tracked and monitored by ground stations at Bangalore, Lucknow, Mauritius, Biak in Indonesia, Bearslake in Russia, Saskatoon in Canada and Svalbard in Sweden/Transo in Norway.

LAPAN-TUBSAT and PEHUENSAT-1: LAPAN-TUBSAT and PEHUENSAT-1 were launched under commercial agreements. LAPAN-TUBSAT is a cooperative venture between Indonesian Space Agency, LAPAN and Technical University of Berlin. It is an earth observation satellite besides a technical demonstrator in control systems. The 56 kg LAPAN-TUBSAT carries two Charge Coupled Device (CCD) cameras with ground resolutions of 5 m and 200 m respectively. It also carries an experiment for message store and forward system.

PEHUENSAT-1 is a 6 kg Argentinean nano-satellite meant to serve educational, technological and scientific fields. PEHUENSAT-1, developed by University of Comahue of Argentina, AMSAT (Amateur Satellite Association of Argentina) and Argentina Association for Space Technology, is intended to provide an experiment platform to perform amateur radio experiments between colleges and universities of Argentina.

With its ninth consecutively successful launch today, PSLV has once again proved its reliability and versatility to orbit multiple satellites and launch satellites in different types of orbit. In today’s launch, several improvements to the vehicle and the Dual Launch Adopter have been proved in flight.