Vikram and Pragyan, two robots on a trip to the Moon, have completed 90% of their journey, having already reached the lunar orbit. After separating from the orbiter, to which they were attached from July 22 to September 2, they are poised to soft land (landing in a controlled manner) on the Moon on September 7.
Vikram, who lands first, is like Neil Armstrong, while Pragyan is similar to co-astronaut Buzz Aldrin. Both astronauts were part of the US Apollo 11 mission that put the first man on the Moon 50 years ago in 1969. Vikram and Pragyan were sent on this journey to the Earth’s satellite by the Indian Space Research Organisation (Isro). Vikram will decide on the exact landing spot when it is 100 metres above the lunar surface, and if all goes well it will touch down 78 seconds later. The preferred landing site is between two craters, Manzinus and Simpelius, about 350km north of the Moon's south pole.

As they get set to land, the two buddies get chatty — understanding why the Moon's exploration is important and the need for a third companion — the Orbiter — who like Armstrong and Aldrin's crew-mate Michael Collins went on the Moon mission but never walked on the lunar surface.

Let’s listen in...

Vikram: What’s this place we're going to?
Pragyan: Moon. It’s the Earth’s natural satellite, and scientists say that one day we will have humans settled here.
Vikram: How far is it from Earth, and are we the first to get here?
Pragyan: It is nearly 4-lakh-km away from Earth and we are not the first. Other instruments have been here before us, and even humans have set foot — Neil Armstrong and Buzz Aldrin were the first. We are like them, you are Neil and I am Buzz. But, we are specifically landing on one part of the Moon — its south pole — which is supposed to be rich in minerals and water.

Vikram: Why were we then sent if so many have been here before?
Pragyan: These Isro guys say that whatever we see and relay back to them will change the way they plan future lunar expeditions. They have sent us to improve people's understanding of the Moon and make discoveries that will benefit them (humanity). We will also help them enhance their understanding of the origins of the solar system. Do you know that our successful landing will make India only the fourth country in the world after Russia, the US and China to achieve this feat and the first to reach the Moon's south pole, that too in the first attempt — that's pretty cool!
Vikram: So we're going where no one has gone before. But how much has this trip cost?
Pragyan: Isro is spending Rs 978 crore — that's less than what it cost to make the Hollywood movie 'Interstellar'! We've taken 48 days to reach the Moon because of the circuitous route we've chosen to take advantage of Earth's gravity, which has helped slingshot our craft towards the Moon.
Vikram: Tell me a little more about the Moon…
Pragyan: It is the closest cosmic body on which space discovery can be documented. Moon gives the best linkage to Earth’s early history as it has an undisturbed historical record of the inner solar system environment.

Vikram: What are we expecting here?
Pragyan: The atmosphere isn't like Earth's, as you would have noticed already. Gravity too is much weaker than Earth's because Moon weighs a lot less. Also, the temperatures will be extreme, worse than the worst place on Earth, and there will be a lot of dust too, you'll know once land.
Vikram: What’s expected of us?
Pragyan: Moon’s origin and evolution needs further explanation and we'll be conducting experiments on the lunar surface. While studying the elements, topography, temperatures, atmosphere and chemical composition, we’ll have a friend, the Orbiter, who’ll also be working alongside.
Vikram: Who’s this Orbiter guy?
Pragyan: He’s like Michael Collins from the Apollo 11 mission. Once we land on the Moon, this fellow will keep going around the Moon but never set foot on it.

Vikram: What will he do?
Pragyan: He’ll carry out extensive mapping of the Moon's surface to study variations in its composition which will help us trace its origin and evolution. He’ll also look for hydroxyl (oxygen and hydrogen) and water molecules.
Vikram: He seems important...
Pragyan: Yes... An older cousin of this Orbiter guy became very famous when he went to Moon in 2008 and found some water molecules. Now, there’s need for further studies on the extent of water molecule distribution on and below the surface. If we manage to find enough water along with other valuable minerals in the lunar soil, the three of us could contribute towards the creation of a future Moon colony. Also, if we do a good job, we could set the tone for the proposed manned space flight our country has planned by 2022.
Vikram: Wow! That's amazing. But I’m told I cannot move once I land on the Moon...
Pragyan: Yes, while the Orbiter will go around Moon, I roll out and will be the one doing the walking on the surface. You have to stay put and relay messages I send you, besides telling them back on Earth what you see and record. Even I get to walk only half a kilometre, moving at a speed of one centimetre per second.
Vikram: When do we return?
Pragyan: We are never coming back buddy. This is our final place. Maybe one day, when these guys come here, they’ll find us.