The SpaceX recently launched SN15. Earlier the initial attempts made to launch the rocket ended in explosions in mid air.

SpaceX rockets exploding

There have been several situations of Space Exploration rocket explosions in the past. This is mainly due to the methane-based propellant used by SpaceX.

The first two prototypes of Starship rockets that were launched in December 2020 and February 2021 failed to land properly and exploded.

The SN8 rocket of SpaceX that was launched in December, 2020 exploded as the engines failed to slow the rocket after it flipped and started descending towards the earth. The pressure in the fuel header tank was low that increased the touch down velocity and exploded the rocket.

The SN9 that took off in February 2021, failed to correct its angle and speed and exploded upon landing.

Latest Test

The latest test that launched SN15 has overcome all the earlier hurdles. This is the first test flight of SpaceX in SN series that did not explode. The pervious prototypes in SN series achieved multiple objectives. However, they all exploded after landing.

The SN15 flew till 10 km and then flipped and descended.

Issue

SpaceX’s Raptor engine uses liquid methane and subcooled liquid oxygen as propellants. The engine is designed to use deep cryogenic propellants, that is, the propellants cooled near to their freezing point. Such propellants increase engine performance, propellant density and also allows to store more propellant in vehicle tanks. However, the issue is that at such low temperatures, the pressure is too low. To the contrary the pressure outside is extremely high where the rocket is burning the fuel to create a forward thrust against the gravity. The scientists believe that the pressure differences probably causes the explosion.