What happened to Chandrayan 2 1

India: lunar probe and comsat need to be checked

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April 22, 2018, 11:44 a.m.

After the early failure of the recently launched Indian communications satellite GSAT 6A, the Indian Space Research Organization (ISRO) is probably playing it safe. The Chandrayaan 2 lunar probe and the GSAT 11 communications satellite will undergo additional tests.

GSAT 6A in space - illustration
(Image: ISRO)
GSAT 6A was transported into space on March 29, 2018 on the GSLV rocket with flight number F08. After the suspension, the usual orbital raising maneuvers had begun, which served to prepare the positioning of the satellite at a position at 83 degrees East in Geostationary Orbit (GEO). After the second orbit raising maneuver, however, contact with the satellite was broken on April 1, 2018, according to ISRO, Raumfahrer net reported.

Most recently, the satellite was observed on an orbit inclined around 3.3 degrees to the earth's equator with an orbit point closest to the earth 25,986 kilometers above the earth and an orbit furthest away from the earth 36,377 kilometers above the earth. Its path changed only by nuances after the communication breakdown.

GSAT 6A during tests on the ground
(Image: ISRO)
The Times Of India announced in its Internet edition that the director of the Vikram Sarabhai Space Center (VSSC) S. Somanath reported that they had analyzed and understood what might have happened on board GSAT 6A. Somanath described the difficulties as a problem in the power system consisting of accumulators, solar cell booms and electronic circuits. A short circuit is assumed which, in conjunction with possibly failing protective circuits, destroyed lines.

In an interview with journalists, S. Somanath wanted to rule out sabotage during the construction of the satellite. The satellite systems were repeatedly tested during construction. Scientists were still trying to regain control of the spacecraft. It cannot be completely ruled out that the satellite may or may not be able to switch to a so-called safety mode ("safemode") in which it will eventually react to radio signals at some point.

Chandrayaan 2 in configuration for the flight to the moon - illustration
(Image: ISRO)
The tests of the nearly completed lunar probe Chandrayaan 2, which was last scheduled for launch in April 2018, are to be expanded. ISRO postponed its launch on the GSLV-F10 rocket to October 2018. In view of the planned course of the mission, there will only be suitable launch windows in a few months, which are about a day or two wide. April would be a suitable starting window that will now be missed for sure. There are other suitable starting windows in October and November. The first week of October is currently targeted.

Chandrayaan 2: Rover Leaves Lander - Illustration
(Image: ISRO)
Chandrayaan 2 (total mass 3,290 kilograms) consists of a lunar satellite, a lander for a soft landing on the lunar surface and a small six-wheeled rover. The program builds on the experiences made with the Chandrayaan 1 probe and is intended to significantly expand the possibilities of Indian lunar research. Chandrayaan 1 was launched on October 22, 2008.

Chandrayaan 1 had reached a lunar orbit on November 8, 2008. She then worked until August 29, 2009. Improvements to Chandrayaan 2 include thermal management. At Chandrayaan 1, the energy input through the reflection of the moon's surface had caused serious temperature problems on board the probe, Raumfahrer.net reported.

GSAT 11 illustration
(Image: ISRO)
India's most modern communications satellite GSAT 11 reached the European space center Kourou in French Guiana at the end of March 2018. Arianespace and ISRO had planned to transport GSAT 11 into space together with another communications satellite in May 2018 (possibly on May 25, 2018) on board the Ariane 5 rocket with flight number VA243. In the meantime, however, it became known that GSAT 11 would be brought back to India.

There is currently no official confirmation from the launch provider Arianespace or the Indian satellite operator regarding the postponement of the launch for GSAT 11. Observers of the Indian space program are certain that the VA243 mission will probably not be able to start in May 2018. Via the short message service Twitter it is spread that VA243 has currently the status "canceled", Indian personnel have started their way back to India.

Unloading the transport container with GSAT 11 in French Guiana
(Image: ESA / CNES / Arianespace / CSG)
Starting GSAT 11 only after a thorough check seems plausible. For the Indian space program in general and the Indian communications satellite program in particular, the new spacecraft with a launch mass of around 5,870 kilograms is of outstanding importance. According to Indian information, it is the heaviest so far from India with new technical solutions and equipment details that represent the latest technical standards.

It should also be emphasized that GSAT 11 has for the first time a main body that consists of the combination of two basic structural elements. One of the elements is previously more or less common for bus systems and payload components with a classic central tube, the second additional element is one for additional payload and with its own central tube section.

Basic structural elements of GSAT 11
(Image: ISRO)
The new three-axis stabilized satellite should enable a total data throughput of over 12 gigabits per second (according to Antrix 2017: 10 Gbps) and provide internet-based communication services and connections to VSAT networks from a position at 74 degrees east in the GEO. With 16 illumination zones in the Ku-Band it could supply the Indian motherland and surrounding islands including the Andaman and Nicobar Islands belonging to India and also connect remote parts of the country. Two special Ka-Band footprints are intended to supply the New Delhi and Bangalore or Bangaluru metropolitan areas.

In order to be able to fulfill its tasks during its design service life of at least 15 years, the satellite - a construction that is based on the new Indian satellite bus I-6K - is equipped with a total of 40 transponders that are installed at the ISRO Space Applications Center (SAC) originated in Ahmedabad. Solar cells on two newly developed arms, which can supply the GSAT 11 systems with an electrical output of up to 11 kilowatts, serve to generate energy.

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Source: Antrix, Arianespace, ISRO, NDTV, SAC, Times Of India, Twitter