Chandrayaan-2: Why Nasa was unable to spot Vikram lander on Moon

HIGHLIGHTS

  • Chandrayaan-2 lander went out of contact during its September 7 landing attempt
  • A Nasa lunar orbiter flew over Vikram’s landing site on September 17 and took photos
  • The photos were shot at dusk when there were long shadows on the lunar surface

The US space agency Nasa has come up empty in its attempt to locate and photograph the Chandrayaan-2 lander Vikram, which went silent during its attempt to land near the south pole of the Moon earlier this month. Ten days after Vikram went out of contact, the National Aeronautics and Space Administration sent its lunar orbiter to fly over the Chandrayaan-2 lander’s landing site in an attempt to determine its fate.

Now, Nasa has released the images shot by its Lunar Reconnaissance Orbiter on September 17 when it flew over Vikram’s landing site. The high-resolution photographs capture a large swathe of the cratered lunar surface. However, Nasa said, they were unable to locate Vikram on the Moon.

Why? Short answer: The photos were shot when it was dusk on the Moon and so, large shadows covered the region.

Want to know more? Read on.

The Chandrayaan-2 lander Vikram, which housed the six-wheeled lunar rover Pragyaan, attempted landing on the Moon in the early hours of September 7. At that time, it was early morning in the south polar region of the Moon where Vikram was attempting to land.

Now, one lunar day lasts around 27 Earth days. This includes around 14 Earth days of daytime and another 14 Earth days of nightVikram’s landing attempt, during which it lost contact with Earth, was made at the beginning of daytime in the south polar region of the Moon.

Don’t remember what happened during Vikram’s landing attempt? Here’s a recap:

  • Vikram began its lunar descent shortly before 1:40 am on September 7. For the first few minutes, everything went according to plan
  • Over 10 minutes after Vikram began its landing, silence gripped the Isro command centre that tracking Chandrayaan-2. The scientists there looked visibly worried
  • At around 2:15 am, Isro chief K Sivan announced that contact had been lost with the Chandrayaan-2 lander

In the days after Vikram lost contact, the Indian Space Research Organisation (Isro) began frantic attempts to re-establish communication with the Chandrayaan-2 lander. Isro’s American counterpart Nasa too joined the effort to determine Vikram’s fate.

On September 17, Nasa’s Lunar Reconnaissance Orbiter flew over Vikram’s landing site and took photos. Those photos were released today with Nasa saying it was unable to spot the Vikram lander. Nasa’s LRO took those photos 10 days after Vikram’s landing attempt when daytime was beginning in south polar region of the Moon.

By September 17, when the LRO took those photos, it was late evening in the area and the sun had begun setting. What this means is that the fading sunlight was hitting the region at low angles.

Now, the south polar region of the Moon — like much of the lunar surface — is riddled with craters. So, the slanting sunrays hitting the ridges of these craters created long shadows on the lunar surface.

These shadows are clearly visible in the photos of Vikram’s landing site released by Nasa. Take this photograph for instance:

Tap to enlarge

The area highlighted in red in the picture above is where Vikram attempted its landing. It is relatively clear, but there are shadows seen in the top and bottom areas of the highlighted region.

This photo below, which is of Vikram’s targetted landing site, offers a much better look at the shadows in the region.

Tap to enlarge

Why are we talking about these shadows? Well, it’s simple: The Vikram lander could be lying in these shadowed areas making it difficult to locate it.

Also remember that it is possible — though the chances are slim — that Vikram went horribly off course during its landing attempt and so, may be lying in an entirely different region than its targetted landing site.

WHAT NOW?

Vikram’s and Pragyaan’s fates are sealed. Currently, it is night in the Moon’s south polar region, which is among the coldest spots in the Solar System. During night, temperatures in the region plunge to below minus 200 degrees Celsius. Vikram does not carry any heating system to survive the bitter cold. By the time sunlight returns to the region, Vikram’s instruments will be permanently damage.

However, there is still hope for locating the Chandrayaan-2 lander. Nasa said its Lunar Reconnaissance Orbiter will perform another flyby over Vikram’s landing site in October. John Keller, the deputy project scientist of the Lunar Reconnaissance Orbiter mission, told news agency PTI that the flyby would take place on October 14 when “lighting conditions will be more favourable”.

NASA

@NASA

Our @LRO_NASA mission imaged the targeted landing site of India’s Chandrayaan-2 lander, Vikram. The images were taken at dusk, and the team was not able to locate the lander. More images will be taken in October during a flyby in favorable lighting. More: https://go.nasa.gov/2n03HuV

Lunar surfaceLunar surface with names of locations
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The LRO will once again take photographs of Vikram’s landing site and with lighting conditions expected to be more favourable, there is a possibility of the Chandrayaan-2 lander being located.

ORBITER A-OKAY

Meanwhile, the Chandyraan-2 orbiter continues to be safe in its orbit around the Moon. Indian Space Research Organisation K Sivan said this week that the orbiter is performing very well and has begun its experiments.

The orbiter carries the bulk of the Chandrayaan-2 mission’s payloads, or scientific instruments. The Chadrayaan-2 orbiter has eight payloads onboard.

Over the course of its mission life, which has been extended from one year to seven years, the Chandrayaan-2 orbiter will carry out a number of experiments to map the lunar surface, determine the presence of minerals on the Moon and estimate the quantity of iced water in the polar regions of the Moon.

So, the sun may have set on Vikram and Pragyaan, but the Chandrayaan-2 mission will keep flying for years to come.

 

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