^Agree. There's a little too much of that nationalism and jingoism in Bagla's reports- and he's supposed to be a science writer! It's okay to mention it, but it shouldn't be the centrepiece or the dominant theme. I don't like Frontline magazine( way too left politically!) but they have excellent science and technology articles by T.S Subramanian and R. Ramachandran, particularly in the area of aerospace. The first, second, 5th, 6th et al are certainly brought up, as they should be, but the accent is on the actual science and technology, and the challenges therein.
India's most ambitious Chandrayaan-2 mission, which was earlier scheduled for October first week, has been postponed till December, according to an Isro source. Unlike the Chandrayaan-1 programme in 2008 that involved only orbiting around the moon, Chandrayaan-2 is a much complicated mission as it involves an orbiter, a lander and a rover. The mission involves a soft-landing on the lunar surface and a rover that will walk and analysis the content on the moon's surface. Being India's most challenging mission, Isro doesn't want to take chances and taking time to fix all glitches in the lunar mission.
As the weight of the Chandrayaan-2 spacecraft has increased, according to the source, GSLV Mk III or Isro's 'fat boy' will now carry the spacecraft as it has the lifting capability of over four tonne. According to the earlier plan, GSLV Mk II which just three-tonne lifting capability was supposed to carry the payload.
Describing India's Chandrayaan-2 mission, the Isro chairman had earlier told TOI, "It is totally an indigenous programme. All components of the Chandrayaan-2 mission, including an orbiter, a lander and a rover, have been developed in the country. There integration is going on and they all are undergoing rigorous tests.
On reaching the moon's orbit, the lander will get detached from the orbiter and soft-land on the lunar surface. The six-wheeled rover fixed within the lander will get detached and move on the lunar surface for around 100 metres. It will spend 14 Earth days (one moon day) and analyse the content. It will also take photos of the moon's surface and relay the images back to the Earth via the orbiter within 15 minutes."
Sources say that this time, the delay was caused because the indigenously developed lander was having trouble with rethrottling. The lander has now gone back to the design table for a design change. "The lander was developing vibrations at the time of rethrottling. The problem appears to be with the thrusters," said a senior level official at the Indian Space Research Organisation (ISRO).
Though the launch has been shifted by just three months but given that the vehicle taking the lander to the moon is also changing, a further delay may not be a surprise. Previously, the GSLV II was scheduled to ferry Chandrayaan 2, now it is reported that the heaviest vehicle in ISRO's stable, the Bahubali or GSLV III, is the vehicle of choice.
The development has taken time, and given that it is the first time India is developing a lander, the programme has faced many glitches like the present one. While no date was announced for the mission for a long time, it was finally said the rocket would take off in April 2018. But the launch was shifted to the next window, October 2018 and now it has been shifted further.Sources say that while postponements are disappointing, one cannot compromise accuracy just to stay ahead in the race. A GSLV Mk III launch costs around Rs 4 billion and it also entails years of research and development. Every component needs to be precise before such an ambitious mission can be launched.
The decision on how many orbits the Lander will make has not yet been taken, but it will be a 100x30 (100km on one side and 30 on the other) elliptical orbit, which means that the entire configuration of the mission has now changed, in effect, causing the delay.“Earlier, the plan was to gradually go down from 100km and reach 18km from the Moon’s surface. From there, the orientation would change, making the Lander go slightly horizontal for about 8.5km and then we were to change the orientation and velocity further to make the soft landing,” a senior member of the Chandrayaan-2 team said.Now, as per the revised plans, the Lander has to go around the surface of the moon before entering the descent phase. Scientists working on the project say that this change in plan could have been avoided as the earlier configuration that was cleared would have achieved the main mission goals.“This additional activity required by the Lander means a host of new hardware added. This is one method of achieving the landing, while the earlier one was another. Our job is to follow what the chairman and other seniors decide and develop things that can successfully complete the mission,” another scientist said.This has also increased Chandrayaan-2 weight from 3,250kg to 3,850kg, which has prompted some changes, including moving to GSLV MK-III instead of the GSLV MK-II, which would have required an uprate to accommodate the additional weight.New configuration & soft landing issueAs per the new configuration cleared after the fourth Comprehensive Technical Review (CTR) meeting held on June 19, among other things, the Lander would require a fifth liquid engine to manage the additional load of having to orbit, along with other hardware including a transponder which it earlier didn’t need.“All these last-minute changes means that we have to test all the new hardware and then begin the fabrication process, which will delay the project. Also, the software algorithms need to change as the mission profile itself has been altered, and even this would need tests,” the scientist said.“The fifth Centrally mounted 800N Steady State Liquid Engine with additional hardware has been included to mitigate upward draft of dust to craft while landing,” the Isro has found.Also, the Lander will have a new Lander Leg configuration with increased base diameter (from 3.6m to 4.34m) which is to improve the stability margins.Why the orbitingAccording to the committee, the Lander is now required to orbit so that it can make “assessment of various system performances before the actual critical Powered,” and to do this, the descent phase requires the inclusion of four reaction wheel and its drive electronics as well as two micro Star Sensors (main & redundant) which will enable it to measure the moving velocity and help land.It will also have transponders for ranging and doppler functions with the antenna configuration and a host of additional supporting systems—power, structure, thermal, etc, will also be added.Besides, there will be two additional propellant tanks (390L capacity), additional pressurant tank (35.5L capacity) among other changes.
No - this to help locate the lander. Its images are compared with previous maps to identify its location, so it can be steered down to a precise landing. This technology has been described before, e.g. by Astrobotic in the US for the Moon and for future Mars landings as well. It will help ensure a safe landing by guiding the lander to the pre-selected safe location.
Probably the LRO images would be used for the terrain map, as they would have 2 or 3 times better resolution. My guess is that the low passes are intended to improve knowledge of the trajectory. Drop to the final pre-descent orbit and make a couple more orbits while the trajectory is checked, then commit to the final descent. Otherwise you are going from the higher orbit to the surface in one go.
Among the key missions to look for in 2019 will be the Chandrayaan-2, Aditya-L1 (India's solar mission) and two demonstration flights of the SSLV (small satellite launch vehicle).
Isro hopes to start the new year (2019) with the launch of Chandrayaan-2, which has already been delayed owing to multiple changes that were needed. Sivan said that they are looking at a launch window between January 3 and mid-March. "We hope to meet the January 3 date," he said, while confirming TOI's August 12 report that the entire configuration of the mission has changed.
The launch of India’s second spacecraft to the Moon has been delayed for the second time this year. Chandrayaan-2 had been expected to lift off in October, after it was pushed back from its original launch date in April.Kailasavadivoo Sivan, chair of the Indian Space Research Organisation (ISRO) in Bangalore, told reporters on 12 August that the agency is aiming to launch the craft on 3 January next year — although the mission has a launch window of any time between January and March. Chandrayaan-2 will carry an orbiter that will travel around the Moon; a lander that will attempt India’s first controlled, or soft, landing; and a rover.Sivan said that there were several reasons for the latest delay, including design changes to ensure a smooth touchdown for the lander. He said these changes have increased the weight of the spacecraft and therefore the amount of fuel needed to complete the mission, which has further added to delays.
NASA's Moon Minerology Mapper hits it big, confirming water ice on the Moon:https://www.nasa.gov/feature/ames/ice-confirmed-at-the-moon-s-polesThe pics seem to show way more ice detected at the South Pole compared to the North Pole - I wonder why. Shouldn't we expect similar apportionment for both poles? What could be the reason for this?I wonder how this could affect the Chandrayaan-2 mission?
