SpaceX’s prototype starship explodes on touchdown again

SpaceX's prototype starship explodes on touchdown again
After six months of construction, six firing tests and an FAA moratorium on approval, the Starship Pioneer SN9 has finally set the world on fire, following in the footsteps of the SN8 and once again embarking on a difficult flight. It hits the ground and explodes, repeating itself.

To launch quick reference

Launch site: SpaceX Starship Base Launch Site Pad B, Boca Chica, Texas

Landing site: SpaceX Starship Base Launch Area Landing in Boca Chica, Texas

Test Starship: Second fully functional full-scale prototype Starship (No. SN9)

Engine: three Raptors (SN49, two new ones with unknown number)

Flight time: 6 minutes and 26 seconds

Maximum flight: ~ 10,000 m (32,800 ft)

Test Objective: To replicate the success of SN8 and reverse the loss of SN8 landing. It didn’t work out.

On Dec. 10 last year, SN8 took the lead and, to most people’s surprise, “almost made it,” failing only to make a soft landing at the last minute. Musk gave the reason for the failure: SN8 in the final landing stage, due to the nose cone fuel tank pressure is insufficient, resulting in insufficient thrust reverse, slow down too fast, resulting in a hard landing explosion (Musk technical term RUD).

SpaceX solution: Take a page out of Falcon 9’s playbook and automatically pressurize the propellant with helium instead of oxygen. The SN8 and SN9 hardware devices are basically of the same type, so it is impossible to make major adjustments in the short term. Therefore, this short-term solution is not only an expediency, but also needs practical verification.

The SN9 still didn’t slow down enough to hit the ground and explode again, creating a huge fireball! The dream of a soft landing was disillusioned again, and SN9 failed to successfully skip the failed landing of SN8.

“We still have to work on landing,” John Insprucker, SpaceX’s chief integration engineer, said in a webcast.

But he added: “We got a lot of valuable data, and the main goal was to verify the control of the starship during subsonic reentry — it looked very good, and we got a lot out of it.”

SpaceX's prototype starship explodes on touchdown again
Why drop to 10km?

The flight path and test difficulty of SN9 and SN8 are basically the same, but the flight altitude is reduced by 2500 meters, from 12.5km to 10km from the highest point of SN8. Why is that?

Before this, Everyday Astronautics, a well-known space media, once revealed that the flight altitude of SN9 was reduced to ~ 10km. Simply put, the test team hopes to improve the chances of a successful soft landing by lowering the altitude and lowering the speed of descent during the landing phase.

The biggest goal of the SN9 test is to replicate the success of the SN8 and overcome the failure of the SN8 landing. The reason for lowering the flight altitude of 2,500 meters is to lower the landing difficulty. Due to insufficient fuel tank pressure in the landing stage of SN8, the reverse thrust is insufficient and the deceleration is too fast, resulting in a hard landing explosion. In addition to avoiding the fate of the SN8 by using helium to pressurize the plane instead of oxygen propellant, the test team could also improve the chances of a soft landing by lowering the altitude and lowering the descent speed during the landing phase.

We know that according to the law of conservation of energy, when an object falls from high altitude, the gravitational potential energy decreases and the kinetic energy increases. The faster the speed, the greater the force hitting the ground will be. Kinetic energy theorem 1/2mV1 ^ 2-1/2mV0 ^2= MGH. When V0 =0, it can be simplified into V1 =2gh. This means that: the falling height decreases, the slower the descending speed, the smaller the force to impact the ground, and the landing thrust will be reduced, thus improving the success rate of soft landing.

Launch process

The full-scale Starship Prototypes uses an all-stainless steel hull (mostly 304L, a few 301) that subverts traditional aerospace materials. It is 50 meters high and has a diameter span of nine meters, equivalent to 1.5 times the diameter of a Boeing 747 airliner.

SN9 belongs to the 9th full-size test spacecraft of the third-generation prototype starship SN series developed by SpaceX (the first generation Starhopper, the second generation Mark series). The serial number is SN9, and it is also the one that has gone the farthest in the starship test road as the successor of SN8. After five months of construction, 60 days of trial and test work, six firings, and the FAA’s suspension of approval, the company has finally reached its high flying moment.

SpaceX's prototype starship explodes on touchdown again
The time on February 2, 2021 now (Beijing time) on February 3, laying, located in the southernmost tip of Texas boca chica capsules starship base test launch site B launch pad, today’s leading role, the prototype starship SN9, three raptor engine start almost at the same time, with 600 tons of thrust, majestic, rolling the world of mortals, day you fly high!

Then fly faster and faster, straight up into the sky. The most powerful methane-enriched oxygen engines in the history of space – three Raptors jet long pure tail flame, like a dazzling exclamation mark for the sky!

About 111 seconds after takeoff, the first Raptor is programmed to shut down. About two minutes and 17 seconds into takeoff, the second Raptor also shuts off, leaving only the single one to continue firing. It then reached its highest point, about 10 kilometers, which is higher than the normal cruising altitude of a commercial airliner.

At the same time, it releases liquid oxygen and condenses into a mass of white steam. There are two main reasons for the release of oxygen. Since the heat of the surrounding air during the flight causes some liquid oxygen to reach the boiling point, the cabin pressure must be released to prevent the danger of excessive pressure. When the engine is successively shut down to reduce the consumption of liquid oxygen, it is more necessary to release the pressure, and a comparable amount of liquid oxygen must be discharged. It saves weight for starships, and liquid oxygen is not harmful to the environment, methane is not.

The SN9 crosses the highest point, and when it takes off about four and a half minutes, the SN9 shuts down the last Raptor. With the front and rear wings equipped with liquid nitrogen gas thrusters to adjust their attitude, the Starship gradually tilts, with its nose cone downward, until it is level with the ground and begins to return and descend in 95% free fall.

This controlled aerodynamic descent (in graphic terms: abdominal-slapping dive) uses the front and rear wings for attitude control (pitch, roll, yaw, etc.) in the same way as a wingsuit jumper with his hands and feet outstretched… This is the second SN9 after the SN8 to perform an unprecedented air flight, which lasts about two minutes.

SpaceX's prototype starship explodes on touchdown again

About 6 minutes and 18 seconds when take off, for about 500 meters from the ground, SN9 began to deduce an astonishing landing turn maneuver (image: dragon put tail), successively two raptor engines, automatically adjust the front wing and rear suspension at the same time, the swing for hull 120 degrees, then rotate 90 degrees, let the boat from the horizontal posture into perpendicular to the ground.

Unfortunately, the second Raptor failed to fire properly and consistently, so the SN9 still didn’t slow down enough. Even a little splashed debris, apparently abnormal.

 

Six minutes and 26 seconds after liftoff, it explodes at a wide Angle (Musk’s technical term for RUD), creating a huge fireball! The dream of a soft landing was disillusioned again, and SN9 failed to successfully skip the failed landing of SN8.

 

A few days before the SN9 fly, a poll was conducted by the Everyday Astronaut We Media account. Participants were asked to estimate the test flight results. Nearly 80% of them believed that the SN9 would make a soft landing. Clearly, there is a lot of confidence in the SpaceX team and a lot of anticipation for the Starship Pioneer. Even though it didn’t work out. But only the more rational attitude towards failure, the more likely to be close to success.

Not far from the explosion of SN9, SN10, despite such a situation, still stands tall in the sky, inheriting the legacy of the pioneers, eager to challenge high flying, replicating the success of SN8 and reversing the loss of SN8 landing.

How divine will the future starship be?

On the last day of the first quarter of last year, SpaceX officially released the Starship User’s Guide 1.0, giving the world a glimpse into the future of starships

 

Unprecedented supercapacity

As the next generation of super-heavy space transportation system, the golden pair of super-heavy rocket (the first stage) and starship (the second stage) will achieve unprecedented and amazing super performance by relying on the two-stage carrier mode. You know, the United States and the Soviet Union in those days to build a moon rocket three or four mode.

The Starship can carry more than 100 tons of LEO in low Earth orbit and 21 tons of GTO in a single launch. Most strikingly, using a parking orbit to refuel would greatly increase starship capacity, leaving other launch systems in the dust.

Whether it’s geosynchronous transfer orbit, lunar orbit, Mars orbit, or even the surface of the moon, the surface of Mars, all over 100 tons. Until now, it was the ultimate in space. You know, there’s only 500 to 600 tons of space traffic in the world every year.

Filled with futuristic sci-fi ships

The manned version can carry up to 100 people at a time, which is the lower limit for a mid-sized airliner. The space shuttle has a maximum of eight people, the soon-to-be launched Dragon has a maximum of seven, and the Soyuz has only three. The luxury manned version of the starship carries less than 100 people, and more space is used to create a “space version of luxury cruise ship”, which is not only equipped with private cabins, large public areas, a central warehouse and a space viewing platform, but also equipped with solar storm shelter to avoid high radiation in space. Comfortable and safe.

Starship is not just a lunar spacecraft, Mars spacecraft, deep space spacecraft, but full of futuristic super spacecraft, the future is expected to carry the earth people into the moon, Mars, solar system human “science fiction spacecraft”.

The manned version of the Starship will also dabble in in-orbit transportation, creating hour-long, point-to-point flights around the world, with most intercity flights taking just half an hour and theoretically one hour between any two places on Earth. This is a huge innovation across both aerospace and aerospace that is poised to upend the pace of transportation. Although this crazy idea was first proposed three years ago, it is becoming more plausible as the development of starships rapidly advances.