Chapter 287 - 280 Sky Question_1

By December 10th, the Aerospace Development Committee had officially established the Tianwen series of exploration missions for 2018:

The launch vehicle was tentatively set as the New Yuan-2B (three-stage configuration), with a Mars orbital capacity of 10.4 tons.

In total, plans were made to launch four Mars surface explorers, designated from Tianwen-1 to Tianwen-4, all with identical functions.

The Tianwen-1 to -4 missions’ explorers consisted of two parts: the lander and the propulsion system, with the latter responsible for decelerating and delivering the 6.5-ton lander into the Martian atmosphere.

Each lander had three components: a heat shield, a surface rover, and a decelerator.

Encased together with the surface rover within the heat shield, the decelerator would first deploy a parachute for preliminary braking upon entering the atmosphere, discard the heat shield after passing through the atmospheric layer, then use retrorockets to slow down, and at a distance of 4-5 meters above the ground, lower the surface rover using cables before breaking away to crash at a distance.

Compared to the lunar lander model, this method aimed to maximize the rover’s mass to enhance its detection capabilities.

The rover would adopt a traditional wheeled design, temporarily named the "Firefly" Mars Rover, with a substantial mass of 2.3 tons.

It was equipped with a new high-power nuclear battery provided by New Yuan, weighing 650 kilograms with a power output of 5.2KW, which could meet all the needs of the Firefly Mars Rover.

The capability of "Firefly" was quite powerful, carrying 16 types of analytical equipment and a multi-functional mechanical arm, relying on its abundant power to explore a roughly 200-kilometer-radius area controlled by AI within two years.

Four rovers were to be sent to four suspected water sites; confirming just one location suitable for synthesizing fuel would be enough.

The Firefly Mars Rover was the absolute mainstay in the selection of Martian landing sites, with the core being the 5KW high-power nuclear battery.

The Aerospace Development Committee placed its trust in New Yuan’s nuclear technology, as the 50-kilogram, 280W RTG nuclear battery supplied for this month’s second-generation lunar spider, Explorer 2, had already been delivered and met the design goals.

The Mars rover’s nuclear battery was basically an increase in the number of battery units, and Mars’s atmosphere offered much more comfortable heat dissipation than the Moon’s, rendering the 5.2KW power output not difficult to attain.

The first nuclear-powered Mars rover, Curiosity, had a weight of 900 kilograms and was equipped with a 45-kilogram, 140W nuclear battery, whose power was far less than that of Firefly.

However, Curiosity’s mission did not include the frantic search for water in preparation for manned landing, so a 140W nuclear battery was sufficient, and therefore, it wasn’t exactly a lack of technology.

Additionally, four resource exploration satellites were prepared for launch into Mars orbit, each weighing about 2 tons. Two CZ-7A Rockets would send them, sufficiently coordinating the completion of the resource survey mission.

Of course, this was just the Tianwen plan, with New Yuan being one of the key contractors.

For Lin Ju himself, although the March spacecraft was already capable of accomplishing the Mars landing mission, the uncertainty of the system made the Mars mission likely more complex than he had anticipated.

The set of operations from the Moon program, such as the synthesis of lunar fuel, the repetitive unmanned spacecraft delivering fuel to the Lunar Orbital Station, and providing supplies to the spacecraft, also needed to be transplanted to Mars.

Because Mars’s higher gravity and atmospheric interference would inevitably double the mass of the entire fuel supply system, and considering that Mars was much farther away and required waiting for an opportunistic window, each mission would have to seize the chance to send as much mass as possible.

Therefore, there was a necessity for the Rocket-4 with a Mars capacity of 200 tons, which was four times that of the Rocket-3.

Furthermore, Xie Liaofu had made some adjustments to the configuration of Rocket-4; Core Stage One would house 39 juxtaposed hydrogen-oxygen engines, and solid rocket boosters would be recovered reusable after splashing down at sea.

The combustion chambers of the hydrogen-oxygen engines used by Rocket-4 would be pressurized by more than 30%, increasing the sea-level thrust to 280 tons without changing the volume, making the core stage thrust alone exceed ten thousand tons.

Xie Liaofu was very fond of Rocket No. 4, mainly because the hydrogen-oxygen fuel was so clean; he disregarded solid rocket boosters.

Rocket No. 4 was now finalized in three configurations: the basic type, type A, and type B.

The basic type would hardly be produced, it was just a 1.5-stage configuration with only the Core Stage One and boosters, and the core stage’s 39 engines could flexibly adjust their working number to operate continuously for 600 seconds, sending the payload into a near-Earth orbit at 300 kilometers with a capacity of 550 tons.

Type A was a two-stage configuration, which could deliver 800 tons to low-Earth orbit, but its purpose was the Moon, capable of sending a payload of 360 tons to lunar orbit.

Type B was a three-stage configuration designed specifically for Mars and was the configuration Xie Liaofu valued the most. With a Mars capacity of 200 tons, the importance lay in the fact that the third stage, which used liquid hydrogen and liquid oxygen fuel, would go to Mars with the payload and complete the deceleration process.

Getting to Mars, even quickly, takes 4 to 6 months, and storing liquid hydrogen and liquid oxygen fuel in space is a significant problem.

Liquid hydrogen requires ultra-high pressure and ultra-low temperature storage environments and constantly corrodes the metal inner walls, leading to catalysis. Long-term storage is highly prone to leakage, and there have been multiple examples in the history of spaceflight.

Generally, for large spacecraft on deep space missions, it is advisable to use storable propellants at ambient temperature, which can be preserved for a long time, with no problem lasting for years.

But this kind of fuel... it is highly toxic, and its specific impulse is barely over 200 seconds, half of what you’d want.

Therefore, Xie Liaofu decisively ruled it out, deciding to use zero boil-off storage technology on the third-stage fuel tanks of Rocket No. 4.

Existing liquid hydrogen storage methods all require venting gas regularly to control the high pressure caused by the evaporation of liquid hydrogen inside the storage tank. The aim of zero boil-off storage technology is to store liquid hydrogen for extremely long periods without any leakage.

Both the Union and NACA had conducted research in this area, but they had stopped after failing to make significant progress. Nevertheless, Xie Liaofu planned to solve this problem in about a year.

Not for any other reason, but for the high specific impulse and clean fuel—long live environmentalism!

And the specifics of the New Yuan’s Mars project were still slowly taking shape in Xie Liaofu’s mind, which is why Androff still didn’t know that for the next two years they would have to continue working on these large rockets, even though he felt that Rocket No. 3 was already sufficient for use throughout the entire era of chemical energy.

...

"Detach!"

seconds after the launch of the Artemis 1 mission, at an altitude of about 160 kilometers, the upper stage carrying the spacecraft detached from the core stage.

The antiquated RL-10 engine started up, and it would continue to accelerate, delivering the Orion spacecraft to the Moon within 48 hours.

The data sent back were extremely perfect, and Claire’s heart, which had been in suspense, was finally able to relax.

The Orion spacecraft was mature and hardly needed any testing. It was only the SLS rocket that was always worrying, but fortunately, everything went normally during the 500 seconds of flight, and the booster debris had already fallen into the ocean, indicating that the design was successful. The more than 5 billion US dollars spent on the first rocket hadn’t been wasted.

"Thank God, it seems that Xiaohei can leave a little happier. Although he canceled the Constellation program, the restart of Artemis couldn’t happen without his support," Claire murmured.

Claire quietly steadied her beating heart and thought she had done quite well. If they were to go to the Moon with three SLSs and a Heavy Falcon Rocket in collaboration, they could implement it by March 2018.

Even without the Heavy Falcon, two SLS launches could still complete the lunar landing mission before the originally promised August 2018.