SpaceX Starship: Key milestones for the world's most powerful rocket

SpaceX's Starship program is the tallest and strongest rocket in the world. It will eventually transport people and cargo to Mars. The latest prototype, SN20 is currently in orbit and waiting to be launched. Many other prototypes have been tested on ground and air, making mistakes sometimes in an effort to improve future flights. Here are some key milestones along Starship's journey to the Red Planet.
Video: Elon Musk's lessons from every SpaceX Starship Explosion

Twenty years of making it happen

SpaceX's Starship SN9 prototype flew 6.2 miles (10 km) from its South Texas location on February 3, 2021. SpaceX image credit

SpaceX was founded by billionaire Elon Musk in 2002 after he sold two businesses, Zip2, a software-service internet company, and PayPal, an online payment provider. His ultimate goal was to establish a Mars settlement business. SpaceX is busy, however. The company has built Dragon cargo ships for the International Space Station and Crew Dragon astronaut spaceships. It also launched satellites for many customers aboard Falcon 9 and Falcon Heavy rockets.

Musk regularly releases far-fetched Mars visions and sometimes alters the names and metrics of systems to send crews, cargo, and rockets. In 2018, Musk renamed his Mars-colonizing spaceflight platform Starship. Musk stated in 2018 that there were two parts to his Mars-colonizing spaceflight system: Starship (or the upper stage) and Super Heavy (or the rocket booster required to escape Earth's deep gravitation well, not needed for other planets and moons).

Similar: View the evolution of SpaceX's rockets through pictures

Key design change

Aerial view of SpaceX's Starship Mk1 prototype, as seen by Elon Musk during his Starship update in South Texas Sept. 28, 2019. SpaceX image credit

Musk initially planned to build Starship from carbon fiber. However, Space.com reported that Musk announced in January 2019 that Starship would instead be made of stainless steel. Stainless steel is heavier than carbon fibre initially, increasing the fuel required for launch. However, Musk stated that stainless steel has better thermal characteristics for spaceflight and would lower the overall cost. Musk later stated that this design change was the best decision for the project.

Starship has seen a few design updates since 2019. Musk decided to install six Raptors engines on the Starship vehicle, instead of seven. Musk also increased the number of Raptors aboard the Super Heavy. He initially decreased the number to 35, then increased it to 31, and finally to 37 Raptors. Musk stated that although not all engines will be required on every flight, at least 24 Raptors will be required to transport the massive craft into space.

Space.com reported that Starship's design was changed unexpectedly in 2021. Musk stated that he was inspired by the 2012 film "The Dictator", and made the vehicle pointier after watching it. "Round doesn't scare me. Pointy is frightening," Cohen's Adm. General. Aladeen, a fictional dictator, said about a missile that he and his engineers had created.

Round-the-moon journey

March 2, 2021. DearMoon invited applicants to its eight-person crew. (Image credit: dearMoon/SpaceX)

Yusaku Maezawa, the Japanese billionaire and founder of Zozo Japanese e-commerce company, purchased a round-the moon trip aboard Starship in September 2018. He was able to fly with several artists on a lunar mission. Back then, Starship was known as Big Falcon Spaceship and Super Heavy was Big Falcon Rocket. Musk stated that Starship had not yet started testing, but that he believed it would be ready for the mission in 2023.

Maezawa briefly considered holding an unpopular "girlfriend contest" with the dearMoon flight in January 2020. However, Maezawa pulled the offer in 2020 just two weeks after the announcement. DearMoon organizers stated that they are looking for eight crewmembers to fly with Maezawa around the moon in March 2021. As of August 2021 there has been no announcements regarding the crew members. The mission is still scheduled for flight in 2023.

Starhopper test program

SpaceX's Starhopper prototype is brought down to land during its fourth and last test hop on August 27, 2019. (Image credit: Elon Musk via twitter)

Starhopper, a Starship prototype at low altitude, looked more like an aerodynamic rocket than a tank. SpaceX conducted two static fire tests at its Boca Chica facility, Texas to assess the engine's performance in 2019. Four short test flights were then performed that year.

The Starship's 1 foot (0.3 meter), first tethered hop took 3 seconds. Starhopper just lifted off and hit the tether limits! Musk tweeted April 6, 2019, a fiery video of the initial static fire test. The vehicle flew four times in total, two with a safety tether and two fully unassisted.

The prototype flew to 65 feet (20m) at its expected altitude on the first free flight on July 25, 2019. The prototype's final flight, before it retired on August 27, 2019, was to reach 500 feet (150 m) in accordance with a limitation set by the U.S. Federal Aviation Administration.

It took two hops to fly high.

Starship's program tried several ground prototypes before it attempted flight. MK1 was destroyed during a tank pressure testing, MK2 was abandoned for a newer design, MK3/SN1 was destroyed during a pressurization trial, SN2 had been pressure tested successfully, SN3 was destroyed during a pressure tank test and SN4 was destroyed after a static fire test. These were just a few of the major prototypes that Starship's program had failed to test.

Starship's SN5 prototype and SN6 prototype performed low-altitude test hops. SN5 reached a height of approximately 500 feet on Aug. 4, 2020 and moved in the sky sideways to reach its landing zone. SN6 also took a 500-foot flight on September 3, 2020. Musk tweeted, "Turns Out, You Can Make Anything Fly Haha!" Musk also shared a video of a tank-like structure moving through the air.

SpaceX intentionally destroyed SN7 in a ground test to collect data for future flights. SN8, which was launched on December 23, 2020, did complex aerial maneuvers and flips at high altitude during its first launch. According to video taken from the landing pad, it flew 7.8 miles (12.5 km) but did not land. This was due to lower than expected pressure in the fuel tank head.

Crash and crash all over again

SpaceX's Starship SN10 Rocket prototype explodes following a successful liftoff at its Boca Chica launch site in Texas on March 3. This view was provided courtesy of SPadre.com. (Image credit: Spadre.com via YouTube

The Starship program launched three additional prototypes to high-altitude flight in a fast sequence between February 2021 and March 2021: SN9 and SN10. Each vehicle flew for 6 minutes, but they all experienced technical issues during landing which resulted either in fiery crashes or aftertouchdown explosions.

Musk tweeted after each flight to explain what happened and to inform Starship prototypes of the modifications he was planning to make to the Starship prototypes in order to improve the program. Musk tweeted, "Looks like engine 2 had problems on ascent & didn’t reach operating chamber pressure during the landing burn, but it was not necessary."

The controversial moon contract

NASA chose SpaceX to be the contractor for future moon missions. This illustration shows the lander design that will carry astronauts to the Moon's surface. SpaceX, Image Credit

NASA chose SpaceX's Starship to replace Blue Origin and Dynetics for the $2.9 billion Moon-lander contract. This contract is part of NASA's Artemis program. NASA hopes to send astronauts to the moon in 2020. The previous target of 2024 was "not feasible" in August 2021 because of delays in spacesuit development. NASA initially wanted to select two companies as the contractors for this stage, but Congress gave NASA less money than it needed for human landing systems.

Blue Origin and Dynetics protested this decision. However, the Government Accountability Office affirmed NASA's choice in Aug 2021. NASA's decision to change its contract to a sole source option at the last minute was acknowledged by the GAO. However, the GAO added that it did not find any basis for the protests as the protesters had failed to prove any competitive prejudice.

Perfect landing for SN15

View of Starship SN15, as it descends to Earth during a May 5, 2021 test landing and launch. SpaceX, Image Credit

SpaceX's Starship SN15 proto-starship made the landing on the 60th Anniversary of America's first ever crewed spaceflight. This was when astronaut Alan Shepard flew into space aboard NASA’s Mercury capsule. SN15 flew 6.2 miles (10km) in the air and performed several maneuvers in midair on May 5, 2021. Six minutes after takeoff the prototype made a safe landing on Boca Chica's concrete landing pad. This was the Starship's latest flight as of August 2021.

SpaceX representatives stated that the new prototype had several changes. SpaceX representatives stated that SN15 includes vehicle improvements across structures and avionics, as well as the engines that will allow for more speed and efficiency during production and flight. This includes a new enhanced avionics suite and updated propellant architecture in aft skirt, as well a Raptor engine design, configuration, and design.

Amazing heights

SpaceX's new Starship prototype briefly stood on top of a Super Heavy rocket booster, marking the highest-ever rocket ever made. Musk tweeted about the Starship stacked, "Dream come to life."

Boca Chica's stacking test involved mating the two vehicles for one hour. The combined Starship system stood 395 feet (120m) tall. NASA's huge Saturn V moon rocket, which was used in the Apollo missions, stood just 363 feet (110m) tall.

SpaceX's first orbital Starship SN20 was stacked atop its Super Heavy Booster 4 at its Starbase facility in South Texas. It was stacked on top of the booster 4 for the first times Aug. 6, 2021. They were 395 feet tall, higher than NASA's Saturn V lunar rocket. (Image credit SpaceX/Elon Musk via Twitter

The Super Heavy is 230 feet tall (70 m) and Starship SN20 stands at 165 feet (50 m). To prepare for orbital attempts, the two vehicles will be subject to numerous technical tests in August.

Orbital flight attempt

SpaceX's Starship prototype in Black-and-White. (Image credit to Elon Musk/Twitter).

Starship is still waiting for its orbital flight test and regulations remain the biggest uncertainties. Space.com reports that the spaceship will launch from the Gulf of Mexico and make a round trip around the globe. The first stage of the Super Heavy rocket will return to Earth in 6 minutes.

The FAA conducted an environmental assessment of Starship's mission. This delayed SpaceX's plans for July 2021 flight. There could still be additional certifications after the assessment is complete.

"Depending on the results of that [environmental] evaluation, it [SpaceX] might also need to undergo a more thorough review which will result in an updated environmental impact report. CNN Business reported that the Federal Aviation Administration can only license a possible orbital Starship Launch after this process is completed.

Original publication on Live Science