NEW DELHI: The
Indian Space Research Organisation (
Isro) had a significant setback this weekend, with the space agency confirming it had lost contact with GSAT-6A, a mega communication satellite that was to provide mobile communications to both civilians and the armed forces.
Although chances of re-establishing contact with it are slim, the agency’s chairman, Dr K Sivan, said efforts were currently under way to establish contact with the satellite. Scientists said a power system malfunction rendered the satellite incommunicado. The cause of this ‘failure’ is still to be determined.
“We are hopeful, but as of now there is no contact with the satellite. If we are just able to speak with the satellite, we can get it back to working as there are several redundancy mechanisms including back-up power,” Isro's chief said.
Isro launches GSLV-F08 carrying satellite GSAT-6A from the second launch pad at Sriharikota (TOI Photo)
How Isro lost contact
Four minutes after executing the second orbit-raising operation, Isro’s Master Control Facility (MCF) at Hassan lost all contact with GSAT-6A.
At 9.22am on Friday, the first orbit raising operation changed the apogee and perigee height to 36,412km and 5,054km, respectively. MCF gave the command to fire the LAM engine for the second orbit raising operation at 9.51am on Saturday. The satellite executed it and the engine fired for 53 minutes and 54 seconds. Soon after, it communicated back, the signals riding electromagnetic waves and covering a distance of 36,000km to reach the ground station within a fraction of a second. Then, all went blank.
Read also: Isro confirms losing contact with communication satellite GSAT-6A
Describing what transpired after the second orbit raising operations, the Isro chief said, “Everything went on as prescribed, a picture-perfect launch and two textbook orbit raising manoeuvres and then the satellite suddenly stopped communication. We are yet to determine what exactly went wrong.”
"After the successful launch of Gsat-6A from Sriharikota on Thursday, Isro was supposed to perform three orbit-raising manoeuvres to take the satellite from the launch orbit to the designated orbit (geo stationary orbit that is at the altitude of 36,000 km). The first manoeuvre was performed successfully on Thursday. The second orbit-raising exercise was performed on Saturday. As the Isro ground station was gearing up for the third manoeuvre, the communication link with the satellite snapped," Dr Sivan elaborated.
Orbit-raising means manoeuvring a satellite in space in stages in order to place it in its final orbit with the help of small thrusters.
On Sunday, TOI had reported that the satellite had experienced hitches in communication and Isro officially confirmed saying, “After the successful long duration firings, when the satellite was on course to normal operating configuration for the third and the final firing, scheduled for April 1, 2018, communication from the satellite was lost.”
Scientists and engineers at MCF, however, haven’t given up hope. They are continuing to work to establish contact with the satellite even as another team was trying to analyse the exact cause for the power failure. “With everything else having gone exactly as per our plans, we are confident that the systems are working well. At this moment, we do not know what caused the power system to fail,” one scientist said.
‘Still hopeful of regaining control’
K Sivan said Isro was trying to establish contact with the advanced communication satellite. “When there are power fluctuations, the satellite goes into a safe mode with all communication lost. This is not unusual.” “However, that has not happened this time,” Sivan told TOI, adding Isro was “still hopeful of regaining control.”
He said, "Our team is trying to re-establish the communication link with the satellite. Though the delinking of signal from a satellite is a common phenomenon, this time the signal delinking is happening for a longer duration. Even if the satellite's primary power has failed, we can use the back-up power like solar power if we are able to re-establish the contact with it."
READ ALSO: Isro chairman says chances of retrieving satellite still alive
“If we are just able to speak with the satellite, we can get it back to working as there are several redundancy mechanisms including backup power. But everything hinges on reestablishing contact, ” Dr Sivan added.
Sivan said scientists were even trying to send non-command messages to see if the satellite responded. But the agency has not seen any success yet.
Y S Rajan, distinguished professor, Isro, said there have been instances of signals going blank. “Sometimes, it may suddenly wake up and sometimes it may not. It could also be an issue of a charge or a recharge (battery) problem. It will take at least two or three days depending on the anomaly. There have been instances of Nasa losing communication with its satellites and getting it back.”
Also hopeful of retrieving the satellite, the Isro chief said, "Gsat-6A is not out of control and we still hope we can reestablish contact with the satellite." On the location of the satellite, he said, "We know the approximate location of the satellite in space by using other satellites and other resources."
GSAT 6A’s mission
With a life span of 10 years, the 2,066-tonne satellite, costing Rs 270 crore, was meant to provide mobile communication through multi-beam coverage.
The satellite was also significant for the military for communication purposes in remote and border areas. This is because Gsat-6A's six metre-wide antenna is three times broader than those generally used in communication satellites. The big antenna was meant to enable the satellite to provide mobile communication across the country through handheld ground terminals. In other satellites, smaller antenna require larger ground stations.
Second failure in seven months
Even as Isro scientists and engineers burned the midnight oil, insiders said the agency was likely to launch a massive quality assurance drive. Given that this is the second major technical issue faced by the agency — a PSLV heat shield separation failure prevented indigenous backup navigation satellite IRNSS-1H from reaching the orbit in August 2017— in seven months, there will be a renewed emphasis on processes, according to an insider.
The mission to launch IRNSS-1H on board PSLV-C39 ended in failure in August last year after the satellite got stuck in the heat shield. The PSLV-C39 took the satellite to orbit but the heat shield tip or the rocket inside which the satellite is housed did not open. It was scheduled to open 3 minutes and 23 seconds into the flight of the rocket.
IRNSS-1H, the eighth in the NavIC constellation, was to replace IRNSS-1A, the first satellite in the constellation whose rubidium atomic clocks had stopped functioning. The clocks are a critical component in providing accurate locational data. The atomic clocks in IRNSS-1A stopped due to issues in critical factors like temperature, rubidium bulb that produce light and electronic power supply.
The navsat stuck in the heat shield, now declared space debris, is still roaming in the near-earth orbit and will ultimately fall on the earth.
Isro’s upcoming launches
On the upcoming launches of navigation satellite IRNSS-1I and
Chandrayaan mission, Dr Sivan, who assumed charge in January, said, "Currently, there is no plan to defer these launches. They will go as per the schedule."
The space agency is gearing to launch the navigation satellite this month. IRNSS-1I will replace the faulty first navsat IRNSS-1A, part of the Indian navigation system or NavIC or desi GPS. The three atomic clocks of the IRNSS-1A that were meant to provide precise location data had stopped working two years ago. Since the 2017 launch of navsat IRNSS-1H to replace the faulty satellite was unsuccessful, IRNSS-1I is, therefore, being launched to replace the first navsat. Currently, there are seven navsats in the orbit covering India and a region extending 1,500 km around it that provide real-time positioning and timing services.
Work is also on in full swing for the Chandrayaan-2 mission. Prior to the launch of the GSAT-6A satellite, the Isro chairman, referring to the lunar mission, remarked, “Preparations for the mission are in full swing. All the required tests are going on. The right time to launch the mission comes only once in a month. Therefore, we are hoping to launch it at the right time in April.”
He went on to add, “As Isro is launching such a complicated mission involving an orbiter, lander and a rover for the first time, we have to take extra precautions. If due to some glitch we are not able to launch in April, then we will try to launch the mission in October-November. If we launch the mission in between, we won’t get maximum benefit due to eclipses. To utilise the full lunar day (14 Earth days) for the moon exploration, the best time to launch the mission after April will be after October.”
According to recent reports, the launch will take place in the latter half of the year.
China’s space dream: How it began and where it is headed
While Isro is powering on with its upcoming launches, China too, is going full steam ahead. Despite the plunge back to Earth of the Tiangong-1 space module - the defunct Chinese space laboratory -- Beijing is continuing with its ambitious plans to send humans to the moon.
A model of the Tiangong-1 space lab module, the Shenzhou-9 manned spacecraft and three Chinese astronauts is displayed during a news conference (Reuters file photo)
The country has come a long way in its race to catch up with the United States and Russia, which have lost spacecraft, astronauts and cosmonauts over the decades. China's "taikonauts" have fared better and Beijing sees its military-run space programme as a marker of its rising global stature and growing technological might, according to an AFP report.
Key highlights of China's space story
* Soon after the Soviet Union launched Sputnik in 1957, China Chairman Mao Zedong pronounced "We too will make satellites."
* A decade later - in 1970 - China's first satellite lifted into space on the back of a Long March rocket.
* Human space flight took decades longer, with the first successful mission coming in 2003. As the launch of astronaut Yang Liwei into orbit approached, concern over the viability of the mission caused Beijing to cancel a nationwide live television broadcast at the last minute. Despite the suspense, it went off smoothly, with Yang orbiting the Earth 14 times during his 21-hour flight aboard the Shenzhou 5.
* Since then China has sent men and women into space with increasing regularity.
* Following in the footsteps of the US and Russia, China is striving to open a space station circling our planet.
* The Tiangong-1 was shot into orbit in September 2011.
China's Tiangong space lab
* In 2013, the second Chinese woman in space, Wang Yaping, gave a video class from inside the space module beamed back to children across the world's most populous country. The lab was also used for medical experiments and, most importantly, tests intended to prepare for the building of a space station.
* The lab was followed by the "Jade Rabbit" lunar rover in 2013 which looked at first like a dud when it turned dormant and stopped sending signals back to Earth. The rover made a dramatic recovery, though, ultimately surveying the moon's surface for 31 months, well beyond its expected lifespan.
* In 2016, China launched its second station, the Tiangong-2 lab into orbit 393 kilometres (244 miles) above Earth, in what analysts say will likely serve as a final building block before China launches a manned space station. Astronauts who have visited the station have run experiments on growing rice and thale cress and docking spacecraft.
* Under President Xi Jinping, plans for China's "space dream", as he calls it, have been put into overdrive.
* The country is looking to finally catch up with the US and Russia after years of belatedly matching their space milestones.
* The ambitions start with a space station of its own, slated to begin assembling pieces in space in 2020 with manned use to start around 2022 -- China was deliberately left out of the International Space Station effort.
* China is also planning to build a base on the moon, the state-run Global Times said in early March, citing the Communist Party chief of the China Academy of Space Technology. The outpost will initially be controlled by artificial intelligence robots until humans are sent to occasionally manage it, the official said.
* But lunar work was dealt a setback last year when the Long March-5 Y2, a powerful heavy-lift rocket, failed to launch in July on a mission to send communication satellites into orbit. The failure forced the postponement of the launch of lunar probe Chang'e-5, originally scheduled to collect moon samples in the second half of 2017.
* The official Xinhua news agency quoted a China Lunar Exploration Programme designer as saying last week that the Chang'e 5 is now slated to land in 2019 and then bring back moon samples to Earth.
* Another robot, the Chang'e-4, is still due to land in 2018 for the "first-ever soft landing and roving survey on the far side of the moon", said Zuo Wei, deputy chief designer of the CLEP Ground Application System.
* China's astronauts and scientists have also talked up manned missions to Mars as it strives to become a "global space power".
(Source: AFP)
What happened to China’s defunct space lab
China's defunct
Tiangong 1 space station mostly burned up on re-entry on Monday into the atmosphere over the central South Pacific, Chinese space authorities said.
The experimental space laboratory re-entered around 8:15 a.m. Beijing time, the China Manned Space Engineering Office said.
Scientists monitoring the craft's disintegrating orbit had forecast the craft would mostly burn up and would pose only the slightest of risks to people. Analysis from the Beijing Aerospace Control Center showed it had mostly burned up.
Brad Tucker, an astrophysicist at Australian National University, said Tiangong 1's re-entry was “mostly successful” and that it would have been better if the space station had not been spinning toward Earth, AP reported.
“It could have been better obviously, if it wasn't tumbling, but it landed in the Southern Pacific Ocean and that's kind of where you hope it would land,” Tucker said.
(Inputs from TNN reporters)
