2 launches, 2 landings in 48 hours or a record weekend from SpaceX

Not so long ago, experts and ordinary people wondered if SpaceX could succeed with the landing of the first stage. And now such landings have become such a routine that they do not even always get into the news.

Nevertheless, this weekend SpaceX set a kind of record. Having launched 2 rockets and landed their first steps a little more than 48 hours. Moreover they did it on the east and west coast of the USA. And besides, the first rocket that launched the BulgariaSat-1 satellite used the already flown first stage and made the most difficult landing in the history of Falcon 9.

The rocket launch took place from the LC-39A launch complex at Cape Canaveral (Florida) on Friday, June 23.

Due to the fact that BulgariaSat-1 was launched into a super-synchronous geo-transfer orbit, it was estimated that this increased the service life from 15 to 18 years. But on the other hand, the first stage had too little fuel for landing. Ilon Mask even expressed uncertainty about a successful landing.

For such a complex landing, even the floating platform had to be sent to 680 km from the launch site (for example, when the same first stage launched the Iridium NEXT satellites, the floating platform was 371 km). The first stage entered the dense layers of the atmosphere at a speed of 1,835 meters per second, it was the highest speed, and accordingly the load and heat for all previous landings. The force acting due to the deceleration of a rocket against the dense layers of the atmosphere increases as the square of the velocity, and the heating increases as the cube of the velocity. Aerodynamic steering wheels are heated to red.

Half a minute before landing, three engines came on in order to slow down the rocket as quickly as possible and to reduce losses to overcome gravity. This method is used when there is no significant supply of fuel for a more gentle and controlled single-engine landing. Which is preferred for Falcon 9. SpaceX were able to improve the three-engine landing maneuver, once called the “suicide maneuver”.

A few seconds before landing, the connection was lost, after which it turned on when the rocket was already standing on all its 4 folding legs on a floating platform. At the same time, the floating platform noticeably “roasted”, and the rocket fell a little on its side.

This launch makes the stage with the number B1029 the first rocket of the orbital class launched from both sides of the United States and landing in the Pacific and Atlantic oceans.

Ilon Mask noted that the stage turned out to be “extra roasted” and almost reached the strength limit of its landing legs due to the hard contact with the floating platform. But nevertheless landed successfully.

In the second launch, on Sunday, June 25, the next 10 Iridium NEXT satellites were output from Vandenberg USA Air Force Base. Landing successfully carried out on a floating platform in the Pacific Ocean. Compared with Friday's launch, the landing was very easy, despite the bad weather.

It is also noted that in this mission were used new titanium steering wheels, which will withstand more heat than the previous version. Now the steering wheels are not painted, as they heat up to red with a quick landing using 3 engines.

Ilon notes that the new rudders have exceeded expectations, and most likely will be able to fly several times without maintenance.

New wheels in comparison with old ones

Thus, after this weekend, SpaceX has already launched 9 launches this year, which is about 22% of the launches in the world, and 70% of launches in the USA.

The next launch is expected in early July, the satellite Intelsat 35e.

Full translation of launches for those who missed:



For those who want to be aware of upcoming launches: launch schedule and launch statistics

Source: https://habr.com/ru/post/404855/

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