HIGHLIGHTS
• Isro lost contact with Vikram during the final stages of its descent
• An unexplained wobble may have caused Vikram to go off course, data suggests
• Isro has located Vikram on the Moon but has not been able to contact it
An inexplicable flip that turned the Chandrayaan-2 lander upside down moments before it was to land on the Moon may explain what happened last Saturday, when the Indian Space Research Organisation lost all contact with the Vikram lander.
Data and readings from the Vikram lander's descent on to the lunar surface, gathered by the India Today Magazine, offer an exclusive glimpse into how the Chandrayaan-2 lander lost contact with Earth during its attempt to land on the Moon.
In the early hours of September 7, the Chandrayaan-2 lander began its descent on to the lunar surface. The descent was to last around 15 minutes and initially everything seemed to be going according to plan.
Around 11 minutes after Vikram began its descent, things went haywire.
• At that point, Vikram was supposed to rotate slightly so that its cameras could map the lunar surface for a suitable landing site.
• During this crucial movement, Vikram unexpectedly and inexplicably performed a somersault.
• For a brief moment the Chandrayaan-2 lander was upside down over the lunar surface.
What this meant was that the reverse thrust-producing engines, which were slowing Vikram down, faced the sky for some time. And so, instead of slowing the craft down, the engines actually pushed the Vikram lander down towards the lunar surface.
This was clearly visible in the final readings sent by Vikram -- at 11 minutes and 28 seconds after beginning its descent, Vikram's vertical velocity (the speed with which it was descending on to the Moon) was 42.9 metres per second. A minute and a half later, the speed dramatically increased to 58.9 metres per second.
It was right after this that Vikram went silent and stopped communicating. It still has not gotten back in touch.