Washington (AFP)

For the third time on Wednesday, a prototype of the future giant rocket Starship, from space company SpaceX, exploded during a test.

These spectacular images may sound like a fiasco, yet these incidents can be part of a new ship's development cycle - and even, in a sense, benefit it.

- What is this rocket?

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SpaceX is developing this rocket with a view to being able to send humans to the Moon (from 2023), then Mars.

But it will also be able to carry satellites to place them in orbit.

Its cylinder is 50 meters high and 9 in diameter.

The future rocket will also consist of a first stage called Super Heavy, to form a machine 120 meters high in total.

It will be renewable, that is to say, it can be reused - the specialty of billionaire Elon Musk's company.

It is a heavy launcher: it will be able to carry some 100 tons in space, according to SpaceX, which speaks of the "most powerful launcher ever developed".

- Why is it exploding?

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Since December, SpaceX has carried out three tests of three prototypes of this rocket, named respectively SN8 (for "Serial number 8"), SN9 and SN10.

The first two got to the ground too quickly upon landing, and crashed into huge fireballs.

SN10, on Wednesday, managed to land vertically, but exploded on the ground a few minutes later.

SpaceX has so far not provided an explanation.

The rocket was not completely straight and "was slightly damaged" on landing, notes Jonathan McDowell of the Harvard-Smithsonian Center for Astrophysics.

“Even a very small methane leak could have caused” this explosion, he says.

- Did SpaceX take advantage of Wednesday's test?

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The characteristic of the tests is to acquire new data to analyze in order to improve the model.

"The tests are not binary," all black or all white, Glenn Lightsey, professor at the Guggenheim School of Aerospace Engineering, told AFP.

"Since the explosion took place after landing, it is very likely that all the objectives were met."

In particular, the prototype reached 10 km altitude, as planned, and it overturned well to place itself in a horizontal position during its flight.

In addition, "the vertical landing, soft, is a spectacular success," said Mr. Lightsey, because the craft has a new method of deceleration.

After each of the three flights, SpaceX also congratulated itself on the excellent tests.

"Starship SN10 has landed in one piece!" Elon Musk said on Wednesday, an hour after the explosion.

Thomas Zurbuchen, associate administrator for science at NASA, paid tribute to SpaceX: “Well done to the iteration without which there is no innovation!” He tweeted on Wednesday evening.

- More breakage ... for a faster rocket?

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These repeated launches are permitted by the very nature of SpaceX.

"To my knowledge, Elon Musk uses his own money for Starship tests, so he does not have to answer anyone except his shareholders," said G. Scott Hubbard, a former NASA who heads a committee of security experts for the company.

NASA, for its part, depends on Congress for its budgets, and ultimately also responds to the taxpayer.

This allows SpaceX to take more risks.

“In the development phase of a project, it's much better to try something quickly,” says Jonathan McDowell.

"When you put people on board, of course, you change your approach, but at this point SpaceX is doing exactly the right thing," he said.

"By accepting more risks and possible failures, as a private company, SpaceX and other similar companies are turning the space industry upside down," said Glenn Lightsey.

A new Starship prototype is already in development.

© 2021 AFP