Chapter 1102 Space-based digital image transmission system


    October 16, 2003, 6:23 pm.


    The Shenzhou-5 return capsule successfully landed in the scheduled return area in central Mongolia Province.


    It is only 4.8 kilometers from the intended landing center.


    This number is quite satisfactory within the reservation plan.


    It’s not even the best result in previous recycling.


    But with the two previous accidents in the United States and Russia, everything on the Shenzhou 5 was not so normal...


    Helicopter No. 736, which was responsible for the search and rescue mission, was the helicopter that Chang Haonan flew in before. He quickly landed near the return capsule. The medical team and search and rescue team quickly arrived to help the astronauts open the hatch cover and perform the first operations inside the capsule. medical examination.


    27 minutes later, China''s first astronaut completed the exit independently and confirmed that all physical indicators were normal...


    At this time, the atmosphere in the command and control hall was much calmer than before.


    For many people who have been fighting for this for several years, or even more than ten years, the emotions burst out at this moment cannot be expressed by cheers and celebrations.


    According to the plan, the commander-in-chief of the manned space program should officially announce at this time that the Shenzhou-5 mission was a complete success.


    But he stood behind the small podium and opened his mouth several times in a row, but he was unable to complete a sentence that he was already familiar with.


    Some of the older comrades even had red eyes, but they restrained themselves from showing it because of the cameras surrounding them.


    Originally, there was a high probability that Shen Junrong should be included.


    But he was diverted by Chang Haonan in advance. After confirming that the Shenzhou 5 return capsule and astronauts were fine, he switched back to the previous topic at the speed of light.


    "Comrade Haonan?"


    Obviously, as an expert in the field of measurement and control communications, Shen Junrong can no longer get rid of this idea in his mind.


    Chang Haonan was also clapping along at this moment. He was called twice by Shen Junrong before he heard someone calling his name, so he quickly turned around.


    "You just mentioned changing the shape of the reentry body to a pointed cone shape...but the effective space inside this shape is too low, and more importantly...the high temperature and ablation caused by aerodynamic heating will be more serious. In addition, There are also problems with the structural strength of the thin-shell cone... About ten years ago, one of our rockets was successfully launched but the payload was damaged because this structure was used inside the fairing..."


    Contrary to many people''s intuition, in fluid dynamics, the shape with the lowest resistance is a rounded blunt nose, which is the bulbous bow of an ocean-going ship, or the shape of the return capsule of a manned spacecraft.


    A pointed cone will actually increase resistance.


    "this…"


    In fact, what Chang Haonan just proposed was just an idea at best.


    Not even an idea.


    Taking the pointed cone as an example, it is just because this shape is easier to calculate, and the result will definitely reduce the thickness of the plasma sheath.


    Therefore, I really haven''t seriously considered the questions raised by Shen Junrong.


    After some thought, he spoke again:


    "High-temperature ablation can be overcome to some extent by increasing the thickness of the heat-resistant coating or using technologies such as active cooling."


    "As for space utilization..."


    After answering this, Chang Haonan was still stuck.


    In fact, the reason why he thought about the communication problem in the black barrier area had nothing to do with the spacecraft -


    After so many years of manned spaceflight, the problem of being disconnected for a few minutes in a black barrier area is actually not a big problem.


    On the contrary, it is very fatal for ballistic missiles.


    As for ballistic missile warheads, they don''t actually care much about space utilization.


    The altitude range of 35-80km is exactly the most critical stage of terminal attitude adjustment.


    Above 80km, the adjustment accuracy is insufficient.


    And the friction during reentry itself will lead to a certain degree of orbital deviation.


    And below 35km...


    Ballistic missiles do not slow down and land. The tail speed can reach up to 15-20 times the speed of sound, which is 5-7km per second.


    After breaking through the black barrier, it took a few seconds to hit the target.


    There was no time to adjust.


    However, due to the existence of the black barrier, the warhead can neither passively receive satellite signals nor actively use radar guidance.


    Therefore, the hit accuracy almost only relies on the gyroscope for orbit calculation.


    Except for short- and medium-range missiles that do not leave the atmosphere during the entire journey, if the circular probability error is 50 meters, it is already a hero among heroes.


    And if the warhead can be guided using synthetic aperture radar...then the hit accuracy of 50 meters is basically the lower limit.


    What''s more, it can also be used to attack targets in action.


    Such as large ships, or important convoys.


    But it was obviously not convenient to share these ideas with Shen Junrong.


    Fortunately, this is not the only way he thinks about reducing or eliminating the impact of the black barrier.


    So quickly change the topic:


    "The pointed cone is just an example. In reality, more complex shapes can be used..."


    "In addition, injecting substances into the plasma flow field...such as sulfur hexafluoride, rhenium hexafluoride, or carbon tetrachloride can also effectively reduce the electron density in the plasma sheath. Of course, these need to be re-entered in the reentry body. The head and side openings, as well as the design of the channel structure, are also a big test for the overall structure..."


    After Chang Haonan finished speaking, it took a while before Shen Junrong spoke again.


    He turned around curiously, only to find that the other party was holding a notebook in his hand and writing rapidly.


    Of course, at this time when so much attention is being paid to them, the "non-business" communication between the two did not last long.


    The media who had been waiting for two days to finally get an interview opportunity swarmed in, and soon someone noticed Chang Haonan and Shen Junrong not far away.


    In the blink of an eye, several microphones with different media logos were handed around...


    …


    A few hours later.


    NASA Headquarters.


    Marville strode into the commissioner''s office and stood in front of Sean O''Keefe.


    There is also a piece of information in his hand:


    "Director, the reconnaissance results from Central Command have been sent back. This is the analysis result."


    As he spoke, he opened the document and put it on his desk:


    "but…"


    Before he could finish speaking, O''Keefe took over:


    "But no abnormalities were found. There was only one S-band signal source, but the communication capacity was extremely low?"


    He didn''t even glance down at the report.


    "Uh...that''s true, but how do you..."


    After the Global Hawk returned, the information was uploaded to China almost as quickly as possible, and was then technically processed by NASA analysts.


    There is no additional process in between.


    "well…"


    O''Keefe shook his head helplessly, took out a few pieces of paper from the side of the computer, and handed them to Marvell opposite:


    "Take a look."


    The latter received it and found it was a translated news briefing.


    Of course, the originals are also attached.


    Chinese.


    The content of the top line is -


    "my country''s first manned space mission was successfully completed, and the space-based digital image transmission system made contributions"


    Although the translation was rather blunt, the title still made Marvell''s heart skip a beat.


    The text is not long, but the content is very important.


    Yun Yun said that we have introduced a set of new technologies that allow the spacecraft to directly transmit data to the Beijing Aerospace Command Center about one-third of the time during orbit, which greatly improves the effectiveness of the spacecraft while in orbit.


    They send signals directly to the capital, while you perform passive reconnaissance missions in Central Asia.


    Being able to get useful information is called having a ghost.


    "They... just reported it directly?"


    Marville is also a veteran of NASA and has some understanding of China''s style.


    Generally speaking, after a new technology is put into use, it will not be said so straightforwardly.


    At least not this soon.


    O''Keefe put his arms on the table and stared directly at the unopened report in front of him. He was silent for a while before continuing:


    "This news is not for their own people, but for us...or, in other words, for other countries that are interested in cooperation..."


    (End of chapter)