Sure enough, it was said by everyone again! India really revised the PPT, and the Chandrayaan-4 mission has undergone major adjustments.
In the India Space Research Organisation (ISRO) announcing a new round of Chandrayaan-4 sample return mission "plans", there have been major adjustments to India's originally announced "large plan" for Chandrayaan-4.
Such a change has surprised many people, that is, India's possible goal of collecting lunar samples will change, what is going on?
Let's take a look at it in detail, I have to say that for India, it is really that the plan cannot keep up with the changes.
India's Chandrayaan-4 major adjustment!
Indeed, since the success of India's Chandrayaan-3 mission, India has announced the Chandrayaan-4 program in a high-profile manner, but this approval time is not long, in September 2024, India officially announced that it has determined the implementation of the Chandrayaan-4 program, and plans to invest 21.04 billion rupees (about 1.78 billion yuan) to launch in 2027.
The mission's goal is to collect lunar soil samples and return them safely to Earth, laying the groundwork for India's future mission to the moon.
And yet? Judging from the Chandrayaan-4 plan announced to everyone on India's Space Day, many people were really stunned, that is, it is stronger than China's Chang'e 5 and Chang'e 6.
Its entire Chandrayaan-4 has a total weight of 9.2 tons, and plans to collect 3~5 kg of lunar samples, of course, India is sampling on the front side of the moon, not on the back, but the amount of lunar samples collected is more than China.
The total weight of the Chang'e-5 probe is 8.2 tons, and the lunar soil sample brought back from the moon is 1,731 grams.
Chang'e-6 – At 8.3 tons, Chang'e-6 is China's heaviest deep-space probe to date, collecting 1,935.3 grams of lunar samples.
Therefore, the India Chandrayaan-4 probe can collect up to 5 kilograms of lunar soil, which is indeed more powerful than the mainland's Chang'e-5 and Chang'e-6, and the goal of collecting lunar soil is much larger.
However, at that time, many people doubted, can India really be so strong? Therefore, many people directly say that India is built on "PPT", and may have to change.
However, only about 2 months later, India really changed the situation it disclosed on the August Space Day, from the Gundam Chandrayaan-4 to a "scaled-down" Chandrayaan-4 sampling scheme.
The initially exaggerated cylindrical structure has been greatly reduced, and as you can see in the new schematic diagram, it is not at the same level at all.
Therefore, such a change may largely cause a major adjustment in the samples collected by India's Chandrayaan-4, which is no longer 3-5 kg. Of course, India has not officially explained the problem of this change, but only given a plan explanation.
At the same time, India gave a plan for the return of Chandrayaan-4 samples, according to the plan, the lunar samples will use a ballistic re-entry return scheme, which must overcome extreme overload and high temperature, so this also has to pay the cost of structural strength and thermal protection. So what is ballistic return?
According to the lift and drag of the spacecraft in the return orbit, different ways are used to recover, and the return spacecraft generally adopts three kinds of orbits in the process of returning to the ground at this stage: ballistic, semi-ballistic and gliding (lift).
Among them, the characteristics of ballistic return orbit are that when the spacecraft enters the return orbit and re-enters the atmosphere, it is only affected by drag and does not produce lift, therefore, the descent speed is fast, the aerodynamic overload is large, the landing point cannot be adjusted and controlled, and a large landing point deviation may be produced.
Early Soviet and United States spacecraft and continental return satellites used this kind of return orbit, and its more common way of living was - "equivalent to the way everyone throws a stone and throws it out of their hands." This is a change for India on Chandrayaan-4.
India Chandrayaan-3 is difficult, Chandrayaan-4 is even more difficult, why?
Indeed, the success of India's Chandrayaan-3 mission is not so easy, because India is not "independent" the entire Chandrayaan-3 mission, it seems that this is India's historic lunar exploration mission node, but without the help of Europe and the United States, India is completely unlikely to succeed, during the Chandrayaan-3 mission, Europe and the United States provided support for India's tracking and control, including the status of Chandrayaan-3, where it went, etc., all completed with the help of Europe and the United States.
Therefore, if India's Chandrayaan-3 is completed independently, then Chandrayaan-4 may be easier, if not, then this later task may also have to ask for help.
Secondly, there is another variable in India's Chandrayaan-4, what is it?
That is Japan, according to the plan, India will cooperate with Japan on the implementation of the Chandrayaan-4 mission, but after so long, it is not clear what the cooperation between the two sides looks like, and as Japan, in space technology, there is no way to independently help India complete lunar sampling, then, whether India will eventually complete it by itself or cooperate with Japan, and again ask other countries to support the completion, this is the variable.
Don't see India's plan change so quickly, but whether it can be implemented is indeed difficult to know, and the announcement of the launch of Chandrayaan-4 in 2027 exists, and India has no way to explain to you with certainty.
Moreover, India has another important purpose under the Chandrayaan-4 mission, that is, to test India's manned technology, which India has also publicly disclosed, that is, the Chandrayaan-4 mission is expected to lay the foundation for India's future manned landing on the moon and safe return to Earth, and will demonstrate docking/separation, landing, safe return to Earth, and complete the main technologies required for lunar sample collection and analysis.
This actually enhances a difficulty for India in the Chandrayaan-4 mission, and if this purpose is added, the requirements for Chandrayaan-4 may be a little higher, and any step that goes wrong may lead to problems with India's Chandrayaan-4.
Therefore, India's Chandrayaan-3 is difficult, Chandrayaan-4 is even more difficult, and more countries participating may be a factor in promoting its stable development, and if it ends up doing it alone, the possibility of the entire project being suspended exists.
Then, whether India's Chandrayaan-4 will be implemented as planned, here can only be a question mark first, it can only be said that lunar sampling is not so simple, nor is it as simple as modifying a few PPTs.
How hard is lunar sampling?
It is true that lunar sampling is not simple, the far side of the moon is more difficult than the front of the moon, of course, this time India still challenges the front of the moon, after all, India does not even have a lunar relay star, if you want to go to the far side of the moon for sampling, it is also impossible.
On the positive side, there are not many countries that can do sampling, so how difficult is it?
First, the first is to go to the moon, to carry out multiple orbit corrections, and to carry out the earth-moon transfer, etc., this step is to be perfectly executed, for India, which has experience in the Chandrayaan-3 mission, there should not be much of a problem.
Second, after going to the moon, to accurately land on the lunar surface, this is the most difficult point, and it is also the point where lunar probes in the world have more failures, because landing on the lunar surface requires strong technical support, and India's Chandrayaan-3 is successful, and there should be no big problem.
Third, this step enters the difficulty, which India has not completed, that is, to conduct lunar surface sampling, which requires surveying and mapping of the lunar surface, drawing, etc., if this aspect is not done well, after releasing its own collection drill bit, if it touches the hard area, there may be mission failure, which is a greater test for India.
- After the acquisition is completed, it is necessary to encapsulate, and then it is necessary to take off from the lunar surface, it is not easy to take off from the lunar surface, after the ignition and take-off of the ascender, it has to go through the stages of vertical ascent, attitude adjustment and orbit injection, and then it has to smoothly enter the orbit around the moon, and then the sample docking, and then return, etc., these are all tests.
- For example, as mentioned above, India adopts a ballistic re-entry and return plan, and if its structural strength and thermal protection are not enough, the task will be in vain.
However, the mainland adopts a semi-ballistic jump return, that is, a re-entry into the atmosphere by "playing in the water", which is differentiated, and it is also a unique lunar sample return technology of the continent.
Therefore, in general, lunar sampling is not easy, which requires strong technical support, and India will inevitably try its best to achieve these difficult challenges when returning from lunar sampling, because these are completely unavoidable.
However, it is indeed unknown whether India's revision of the PPT will be revised again.
As long as there is no modification like the return of Martian samples from Europe and the United States, because their modification has become "far away" and they have not yet found a good way to bring it back. In fact, this also shows that on space missions, there is time, but the plan cannot keep up with the changes.
This time, India said that the completion of the manned spacecraft program by December 2028, the establishment of the India space station by 2035, and the manned landing on the moon by 2040 still have a lot of room for change, and India still faces huge challenges to achieve these goals.
Moreover, in terms of tasks such as building space stations alone, the difficulty is much higher than that of satellite research and development, which is inseparable from the support of cutting-edge technology and expertise, and now India still needs to greatly improve its own technical level to complete it.
Instead of modifying and modifying for a while, in order to simplify the task, it is like Chandrayaan-3, which does not have any great results for everyone to output, then even if the task is successful, it will have no great value.
I am not denying here that India will certainly not implement the plan, it will certainly not work, but the plan must be based on the actual situation, and under the difficult challenges, there is still a lot of room for change.
Therefore, if India wants to complete these tasks, it still needs to be nu, and this is the general situation. It is also expected that India can complete the Chandrayaan-4 mission as soon as possible and realize the competition on the moon, as a country in the second echelon of spaceflight, if this step is achieved, it may make its own comprehensive aerospace strength ranking, at least a notch, right?
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