September 7, 2019, was a very important day for all science explorers. Because on this day Chandrayaan-2's Vikram lander was going to land on the moon. If it would have successfully landed on the surface of the moon, then India could have been the fourth national country after the United States, China, and Russia to successfully land the lander by soft landing on the surface of the moon. And at the same time, India could have been the first country to drop an instrument in the South Pole of the Moon. Because no country has done it before.
Everything was going well and Vikram Lander was getting closer to the moon. But when it was only 2.1 km away from the surface of the moon, then for some reason it lost the communication with our scientists.
Then after a few hours, the scientists didn't know what actually happened with the lander and where it was. But after that, the orbiter of this mission finds its current location through thermal imaging.
Then after a few hours, the scientists didn't know what actually happened with the lander and where it was. But after that, the orbiter of this mission finds its current location through thermal imaging.
But so far it is not clear that is it okay or is there some damage to it. ISRO's scientists thinking that it has been a hard landing rather than a soft landing.
If technically seen it then it is very difficult to communicate with this lander. But scientists are doing every effort to communicate with it.
If technically seen it then it is very difficult to communicate with this lander. But scientists are doing every effort to communicate with it.
They will continue to communicate for up to 14 days. Because the rover Pragyan inside the lander was configured to work for 1 day on the moon surface, where this 1 day on moon equals to the 14 days on earth.
It is important to say here that if the scientists of ISRO are can't communicate with the lander then this does not mean that the Chandrayaan-2 mission has been unsuccessful.
Because the Vikram Lander and the Pragyan Rover were only 5 percent of this mission. The remaining 95 percent is the job of the orbiter that is still working well in a very expecting way.
The cameras in this orbiter are far more superior to any spacecraft that ever until now sent to space. And it will continue to provide us important information about the moon for the first seven years.
In this article, we will learn what the Chandrayaan-2 mission is, why it is so important to us, What we have learned from this, how it was sent.
And finally, by analyzing technical data from ISRO, we will know what really happened to Vikram Lander when it was landing on the Moon.
History of Chandrayaan-2
Inspired by the success of the Chandrayaan 1 mission, on November 12 in 2007, Indian space agency ISRO and Russian space agency ROSCOSMOS sign a contract.
According to this contract, it was settled that the two space agencies would work together to create Chandrayaan-2.
Where ISRO was given the responsibility to build orbiter and rover and ROSCOSMOS was given the responsibility to build lander.
In 2008 on September 7, this project was approved by the Indian government, chaired by Dr. Manmohan Singh, the Indian Prime Minister of this time.
Under the supervision of these two space agencies, in August 2009 the design of Chandrayaan-2 was completed.
According to the first permanent plans, ISRO was timely finalize the payload of Chandrayaan 2. But in spite of all this, the mission had postponed from January 2013 and was rescheduled in 2016.
Because ROSCOSMOS couldn't make the lander at that time because they were working on the Phobos Grunt mission at this time. The purpose of this mission was to go to Mars satellite Phobos and come back to Earth with some samples of this.
Even though Phobos Grunt's rocket launches successfully from earth but when it was in the way to go to Mars and it needed a rocket bomb or rocket propulsion, then for some technical errors the rocket was got stopped.
As a result, instead of going to Mars, it was beginning to move around the Earth's lower orbit. However, many attempts were made to reactivate it but it could not be reactivated. For which the Phobos grunt mission was failed.
As a result, instead of going to Mars, it was beginning to move around the Earth's lower orbit. However, many attempts were made to reactivate it but it could not be reactivated. For which the Phobos grunt mission was failed.
Now the problem was that Chandrayaan-2 was supposed to be launched in 2016, but the lander used in it was built by ROSCOSMOS, where they used the technology that was used in the Phobos Grunt Mission.
Since the Phobos Grunt Mission was failed so the ROSCOSMOS was needed to reinvestigate their design and technology once more time.
When ROSCOSMOS saw that they would not be able to build the lander until 2015, they removed their hands from the Chandrayaan-2 project. Then ISRO decided that they would make the lander themselves. And later they made the lander itself.
After being rescheduled several times, It was finally launched on July 9 in 2019 from the Satish Dhawan Space Center in Andhra Pradesh, with the GSLV Mk III rocket.
What will Chandrayaan-2 do?
If we talk about the scientific goal of this mission, then it is to study the topology of the moon, to study the exosphere of the moon, find out the mineral in it that is to find if there are any elements in the moon surface and also to find if there are any hydroxyl group that is to find the water ice signature on the moon.
It has been already said that the 95% work of the Chandrayaan-2 mission would be done by the orbiter. This orbiter will map the entire lunar surface to create a 3-dimensional map so that we can find more information about the moon.
The radar used in it will also map the surface of the south pole of the Moon during studying the water ice that will provide us with more information about this Unxplode area. And it will also find out the thickness of the lunar regolith.
The soils in the Moon is very different from the earth's soils. Because the soil of the moon is made by the mechanical disintegration of basaltic and anorthositic rock, which was created by the moon's collision with the Meteors, Sun, and other space-charged particles.
This is why most scientists prefer the moon soil as regolith instead of calling soil because first, it does not contain organic content Secondly it contains 1cm diameter of grains or less.
Parts of Chandrayaan-2?
Chandrayaan-2 was three in one mission which means it had an Orbiter, a Lander called Vikram lander, and a Rover with six wheels called Pragyan.
In the first year of this mission, news came out that American Space Agency NASA and Europian Space Agency ESA wanted to put some of their instruments into this orbiter.
However, a few months before the launch of the mission, an agreement was reached between ISRO and NASA, After which NASA planted a small Laser Retroreflector in the Vikram Lander.
They fitted it to calculate the correct distance between the lander and the orbiter. Since it was a passive instrument, so It didn't need to have to be activated for doing work.
This means that if the Lander can't send signals for some reason and if there is a problem with it so the orbiter can still find its location.
Parts of the Orbiter
Chandrayaan-2 was sent to the moon with a GSLV Mk III rocket. If we talk about the payload of this mission, then ISRO has installed seven great scientific instruments in their orbiter -
1. Collimated Large Array Soft X-ray Spectrometer(CLASS):
The purpose of installing it was to map the abundance of minerals on the lunar surface.
2. Solar X-ray Monitor(XSM):
The purpose of installing it was to look at the emissions of solar X-rays.
3. Dual Frequency L and S band Synthetic Aperture Radar(SAR):
The purpose of installing it was to find different types of constituent and water ice that are expected 10m below the Moon's surface.
4. Imaging Infra-Red Spectrometer(IIRS):
The purpose of installing it was to measure the abundance of water/hydroxyl on the surface.
5. Chandrayaan-2 Atmospheric Compositional Explorer 2 Quadrupole Mass Analyzer(ChACE-2):
The purpose of installing it was to study the lunar exosphere.
6. Terrain Mapping Camera-2(TMC-2):
The purpose of installing it was to map the lunar surface in three dimensions using two onboard cameras.
7. Orbiter High-Resolution Camera(OHRC):
The purpose of installing it was to examine the surface, particularly the landing site of the lander and rover. The resolution of this camera is 0.3m that is far more superior to any spacecraft that ever until now sent to space.
Parts of the Lander
The lander of this mission was named Vikram, that was named after Vikram Sarabhai, the father of the Indian Space Research Program. If we talk about the payload of this Lander, then ISRO has installed four great scientific instruments in their Lander -
1. Instrument for Lunar Seismic Activity (ILSA) or Seismometer:
The purpose of installing it was to report the moonquakes around the landing site of the lander.
2. Chandra's Surface Thermophysical Experiment (ChaSTE):
The purpose of installing it was to study the thermal property of the moon's surface.
3. Radio Anatomy of Moon Bound Hypersensitive ionosphere and Atmosphere (RAMBHA-Langmuir Probe):
The purpose of installing it was to measure the plasma density of the lunar surface.
4. Laser Retroreflector:
The purpose of installing it was to calculate the correct distance between the lander and the orbiter.
Parts of the Rover
The Rover was built to work with Solar Energy. In this Rover 6 wheels were fitted, these 6 wheels were fitted to travel 500m distance on the moon surface from the landing position of the lander at a speed of 1cm/s.
Its job was to do the chemical analysis of that place and send that data to the lander. After that, the task of the lander was to send this data to ISRO. It was configured to work for 1 day on the moon surface, where this 1 day on moon equals to the 14 days on earth.
After that, it would stop working by itself because it was not made as powerful enough to withstand the cold of the moon night. If we talk about the payload of this Rover, then ISRO has installed some great scientific instruments in their Rover -
1. Stereoscopic 3-D Vision Camera:
The purpose of installing this camera so that even when on Earth, scientists from ISRO can see the 3-dimensional view of the surroundings of the rover.
2. Leser Induced Breakdown Spectroscope.
3. Alpha Particle Induced X-ray Spectroscope.
Journey of Chandrayaan-2
Chandryaan-2 was launched on July 9 in 2019 from the Satish Dhawan Space Center in Andhra Pradesh, with the GSLV Mk III rocket. After this launched it took 48 days to reached on the moon's orbit.
NASA's Apollo took only 4 days to reach that moon. Where Russia's Luner 2 took only 34 hours to reach the moon. So the question is why did Chandrayaan-2 take so long to reach the moon?
Actually, we can send any spacecraft to the moon in two different ways -
1. The first method - The first method is that if you have a powerful rocket, then it can carry a lot of fuel with it. For which we can directly send it to the moon. As a result, it reaches the moon in a very short time.
But if you don't have a powerful rocket that can carry a lot of fuel. So we can't directly send it to the moon because it can't carry that much fuel that is needed to reach the moon. In this case, we use the following procedure
2. The second method - In this method, we use the technology that we use to launch the satellite. Which means we use rockets to reach our satellite only in the lower elliptical orbit of the earth.
When our satellite reaches that orbit, then the rocket gets detached from the satellite to reduce its mass. After that, by using the earth's gravity and the engine of the machine the orbit is then lengthened until the machine gets reaches the moon's orbit. So this process takes a lot of time.
Since the GSLV Mk III rocket was not as powerful as NASA and ESA's rockets, ISRO used this second technology in the Chandrayaan-2 mission.
When Chandrayaan-2 was reached the Moon's orbit, then it was successfully performed the fifth Lunar bound orbit maneuver by using the propulsion system in the module. As a result, the module successfully reached the lower orbit of the Moon.
When our module was 100km away from the surface of the moon, the Vikram lander was successfully separated from the orbiter and then it was reached to close to the moon's surface.
After that, the lander was scanning the surface of the moon so that it could land in a place where there was no danger for it. After scanning the landing site, the landing process was started.
Everything was going well and the Vikram Lander was getting closer to the moon. But when it was only 2.1 km away from the surface of the moon, then scientists were lost their communication with it. Other scientists, including ISRO, thinking that Vikram had a hard landing.
If we talk about landing, then it can be done in two ways - first a soft landing and secondly a hard landing.
Soft landing - When a spacecraft lands comfortably in a place i.e a landing where it doesn't hurt, then such landing is called a soft landing.
For example, the landing of an airplane at the airport is a soft landing.
Hard landing - When we cannot control the landing of a spacecraft, then, the spacecraft may be crashed with the planet and some of its parts get damaged, then such landing is called hard landing.
Technical Data Analysis
Technical Data Analysis from ISRO when Vikram was Landing -
Due to signal delay issues, it was difficult to control its landing from the earth. For this, the computer in the Vikram lander was automating this process.
The hazard avoidance camera in it was making sure it's landing in such a place where it could not be damaged. The other instruments were for continuously calculating its velocity to ensure that it does not hit the surface of the moon.
In Vikram lander, there were 5 main engines and 8 steering engines respectively. Of these 5 main engines, the work of 4 engines was to reduce the velocity of the Vikram. Where there was another one engine in the middle of the lander that was working to land it safely.
Vikram's landing would have been given performed in three different phases. So that its speed becomes almost zero to reach the moon's surface and it can land comfortably on the moon.
Rough breaking Phase
The first phase of this Lander was the Rough breaking Phase, which went on for about 10 minutes. This phase was going very smoothly and out of these 5 engines, 4 engine was working properly to reduce the velocity of the Vikram.
But three to four minutes later, Vikram's trajectory appeared to be curved. Maybe it was Vikram's velocity that wasn't enough to count the gravity of the moon. As a result, Vikram leaves the moon orbit and begins to drift towards the moon for the gravity of the moon.
Nearly for 5 minutes, the horizontal velocity of Vikram was almost 1 km/s where it's vertical velocity was 33 m/s which was very less.
With time, this velocity was decreasing and after nearly 10 minutes when Vikram was just almost 16 km above the surface of the moon. Then it's horizontal velocity was decreased by almost 263 m/s where the vertical velocity was almost 72 m/s. That was what was expected.
The problem happened when Vikram was switching to the proper landing phase after crossing the rough breaking phase. Where there were two phases called the Absolute Navigation Phase and Fine Breaking Phase.
These phases were needed to bring Vikram closer to the moon and for aligning all its legs towards the surface of the moon. If we were talking about distance, Vikram would have been taken 400 meters down from 7 km above.
But before that happens, there is some anomaly happened. This anomaly occurs when Vikram was almost 4km above the surface of the moon. Look at this it seemed as the lander was got some tilted.
But why it happened is difficult to say, because there are maybe many reasons behind this, for example - One of its engines was shut down, Maybe its onboard computer was not able to command properly and there may be other reasons.
But after that Vikram was again gain the expected trajectory, but he continues to deviate from it.
The news came from ISRO that their communication with Vikram was lost when Vikram was only 2.1km away from the moon's surface.
However, the orbiter of this mission has found the location of this lander through thermal imaging, but the communication has not yet been established with it.
How scientists in ISRO are trying to communicate with the lander?
From ISRO's Deep Space Communication Center in Bangalore, ISRO will continuously send a special type of frequency signal for communicating with Vikram lander.
Now if Vikram's communication device is somehow intact, it will respond to receive ISRO signals.
And even if it is not possible to communicate with the lander, then also the 95% of this mission will be successful because of the lander of this mission continuously working well and it will continue to provide important information for the next seven years.