What seems to have touched the popular imagina tion is that the current launch window ends on July 16 and if this window is missed there could be an indefi nite delay in rescheduling the launch. Coupled with news reports that checking and correcting the error could take up to 10 days, this has led to dire pronounce ments of an indefinite postponement of the mission. The 'launch window' is determined by several factors. One of the most important considerations is that any spot on the moon receives sunlight for approximately 14 (earth) days before being plunged in night for anoth er fourteen. The landing has to be timed so that it maxi mises the overlap with the sunlit days on that spot. This is because the lander and the rover need solar energy toi power them and to keep the instruments warm. 'Therefore, given a landing spot that can be seen from the earth, the landing date has to coincide with the sixth phase of the moon (first quarter) as seen from the earth, on that spot. Secondly, once placed on the moon orbit, Chandrayaan-2 must have full visibility to the ground station, which will determine the time of operation of the landing. From the date of launch to the datei of landing, the planned interval is about 54 days. Much of this time is needed for the Chandrayaan-2 mission to make various orbital manoeuvres and operations, but there is a leeway of a day or two to take some decisions. A window that takes all this into account, is available for about 10 minutes on each day now for about a week. Such a windo can be found every month. Other tight er windows are available but are high-risk options. So even if Chandrayaan-2 misses its rendezvous with thei moon this month, it will find a date, perhaps even next month, that will be suitable.
