SpaceX achieves the its first soft splashdown of Starship, Super Heavy Booster on Flight 4 mission – Spaceflight Now

For the fourth time in just more than a year SpaceX has launched a test flight of its huge Starship rocket at its research and development center in south Texas named Starbase. The launch, which is dubbed Flight 4, push the rocket towards its aim of becoming a reusable rocket.

Update at 2:32 p.m. (EDT): Updated details about the mission.

For the fourth time in just more than a year SpaceX has launched a test flight of its huge Starship rocket at its research and development center in south Texas named Starbase. The launch, which is dubbed Flight 4, push the rocket towards its aim of becoming a reusable rocket.

Like the previous three launches Flight 4 did not have a payload, and instead flew in a suborbital path. In contrast to the previous flights, Flight 4 saw a gentle downsplash of the Super Heavy Booster (Booster 11) as well as from that of the Starship higher the stage (Ship 29). The liftoff was scheduled for 7:50 a.m. CDT (8:50 a.m. EDT 1250 UTC) at the time of the opening of the 120-minute window.

This Wednesday SpaceX put the Ship 29 over Booster 11 to form the 121 millimeters (397 feet) Starship rocket. In a blog post posted on X (formerly Twitter) on the 1st of June SpaceX its founder Elon Musk said his belief that “the main goal of this mission is to get much deeper into the atmosphere during reentry, ideally through max heating.” In the wake of the mission, Musk was elated at the return of the Starship “despite [the] loss of many tiles and a damaged flap.”

At the time of Flight 3, the upper stage began to roll in uncontrolled ways which prevented the vehicle from relighting any of the 6 Raptor engines. However, because of its capability of connecting to SpaceX’s Starlink satellite-based internet service, a different aspect of SpaceX’s business it was capable of streaming high-definition camera footage of its return to earth through a cloak of plasma.

“The lack of attitude control resulted in an off-nominal entry, with the ship seeing much larger than anticipated heating on both protected and unprotected areas,” SpaceX stated in a blog post-launch. “The most likely reason of the roll that was not planned was identified as blockage of the valves that control roll. SpaceX have since added thrusters for roll control on its forthcoming Starships to enhance attitude control redundancy, and upgraded equipment for better resistance to blockages.”

Additionally it was it was discovered that the Super Heavy Booster from the previous flight closed down six thirteen Raptor engines that were utilized during the boostback burn. The engines did not come back online when it attempted to do the landing burn.

“The booster had lower than expected landing burn thrust when contact was lost at approximately 462 meters in altitude over the Gulf of Mexico and just under seven minutes into the mission,” SpaceX declared. “The most likely root cause for the early boostback burn shutdown was determined to be continued filter blockage where liquid oxygen is supplied to the engines, leading to a loss of inlet pressure in engine oxygen turbopumps.”

“Super Heavy boosters for Flight 4 and beyond will get additional hardware inside oxygen tanks to further improve propellant filtration capabilities.”

After the successful flight of Flight 4, Musk teased ahead to an impressive achievement to be achieved by Flight 5: catching the Super Heavy Booster using the launch tower’s “chopsticks.”

Eyes on the Moon

Flight 4 was an important mission that was not just for SpaceX however, but also for NASA. The rocket will enter the center stage when NASA begins its Artemis 3 mission, which is scheduled for launch in September 2026.

Lisa Watson-Morgan is the director for the Human Landing System program, and her team continue to collaborate with SpaceX to learn more about the development of the rocket that will act as the Moon landing area for the not yet named astronauts on the Artemis 3 and Artemis 4 missions. She spoke to Spaceflight Now in the lead towards the Flight 4 launch.

“It was great to see the lessons that came out of [flights] one and two and to see how that was employed either through manufacturing, production, through operations of how Flight 3 was conducted,” Watson-Morgan explained. “There there were no problems with Raptor. There were no fires and lots of consistency, honestly about the engines. If you can get the engines all lit on, in our case it was an important victory.”

She also noted that although the Raptor light-up on the upper stage of Flight 3 wasn’t able to be achieved, there’s plenty of time for reaching this important milestone. Watson-Morgan declared that they’d have to witness it being demonstrated in the latter part of 2024 or the early 2025.

“As SpaceX continues to mature their Raptors, because they’re working through their design and development, as they do that, they’re making modifications and adjustments and changes,” Watson-Morgan added. “And all of that’s getting incorporated into an updated build sequence.”

One of the accomplishments which Watson-Morgan and NASA observed included the transfer of propellant that transferred the liquid oxygen (LOX) to the ship’s header tank into its main, upper-stage LOX tank. This was a plan to satisfy the $53.2 million Tipping Point contract with NASA’s Space Technology Mission Directorate (STMD) with the requirement of demonstrating how to transfer 10 tonnes of propellant.

Watson-Morgan stated that, while the HLS office was not directly involved in the demonstration however, representatives from STMD agreed with SpaceX in that it was a very successful demonstration. It’s the first step towards the process of conducting the transfer of propellant from ship to ship which is one of the major aspects that will be used in the SpaceX mission to Artemis Moon landings.

SpaceX’s idea would be to send a tanker version the upper stage of the ship in low-Earth orbit. The company would then launch a number of ships that would dock with the tanker, and inject propellant into it, that would then transfer it onto an HLS Starship version Starship before heading out to the Moon.

“Prop transfer” is the key that opens the door to the world. It truly is. It’s the only way to Mars and it’s the only way for our South Pole and really, it’s our long pole. We’re doing everything we can to prepare for that and to assist SpaceX in that regard,” Watson-Morgan said. “In addition, we’re doing all we can to help Blue Origin with it because they have that as well in their concept.”

The number of fueling flights headed towards the tanker does not have a precise and quick number as of now Watson-Morgan explained, since it’s unclear the amount of propellant that needs to be moved.

“It’s dependent on the six tanks. It’s contingent on will we need to transfer. It’s contingent upon what are the other goals we’d like to demonstrate and the length of time we need to complete the flying tests?” Watson-Morgan said. “And that’s why it might be just a couple or there could also be more than just a couple. It all depends on our goals.”

“One thing that I appreciate much about SpaceX is that they are willing to be open and fluid with objectives and open to more objectives, if NASA believes we need them, depending on the timing.”

Though she was limited in what she could talk about it, Watson-Morgan stated that SpaceX is working on a smaller engine similar to a thruster that will aid in the Prop Transfer demonstration. She also said that a milestone in development for that will be announced at the end of this year.

“Our group has been amazed. They’ve created this engine in just a half-year and, thus far, performing very extremely well,” she said.

Starship expansion

A large part of the timetable for the propellant transfer is contingent on the ability to launch several Starship missions using a larger Launch tower SpaceX currently operates. SpaceX is currently working on building another tower at Starbase.

To accomplish this they made additional components and segments at at NASA’s Kennedy Space Center in Florida and barged them down to Texas. Four tower segments were shipped earlier in the year, and earlier this week they loaded two more segments on the barge, as well as the tower’s “chopsticks” and their elevator system’s supports.

Watson-Morgan stated that this propellant transfer operation can be carried out using two towers at Starbase However, NASA is keen on doing everything to ensure there is a Starship launch capabilities can be launched at KSC too. This week is when NASA’s Federal Aviation Administration (FAA) will hold public scoping sessions to get input on permitting around 44 Starship launches annually from the historic Launch Complex 39A.

In parallel, the Department of the Air Force is conducting an identical evaluation for Starship launches either from Space Launch Complex 37, which was the former launch pad of the ULA’s (ULA) Delta 4 Heavy rocket, or an upcoming launch pad known as SLC-50.

“We certainly want to witness the results of that. We must see it through the uncrewed demonstration to be sure, and obviously, we’d like check that out before making sure everything is in order,” Watson-Morgan said. “We will go ahead and have pad checkouts and all that and operational readiness reviews in advance of it.”

One of the provisions of SpaceX’s HLS agreement with NASA is that it will conduct the uncrewed landing Starship in the Moon prior to the Artemis 3 mission.

Humans are in loop

As they work on the Starship for humans, the human-rated version. Starship as well, they’re collecting information from the Astronaut Office, which is located within NASA’s Johnson Space Center. Watson-Morgan, who refers in them the term “the crew” for shorthand says the office provides insights and opinions about the capabilities of specific components of the vehicle, including the control system, interface and where handles are placed.

She noted that the HLS office mostly works alongside astronauts Raja Chari and Randy Bresnik who has been part of this process “since the very beginning.” Watson-Morgan added she also has members from the office of astronauts who are on the control panel.

“We have a Human Landing System control board, where any requirements changes or updates or how things are implemented get to go through their formal board actions and the crew’s a voting member,” she explained.

On April 30 on April 30, at SpaceX Headquarters in Hawthorne, California, NASA astronaut Doug “Wheels” Wheelock and Axiom Space astronaut Peggy Whitson performed the first integrated test of Axiom’s pressure-sensitive spacesuits along with mockups of the Starship elevator and an airlock.

“Overall, I was pleased with the astronauts’ operation of the control panel and with their ability to perform the difficult tasks they will have to do before stepping onto the Moon,” said Logan Kennedy, lead for the surface activities of the NASA HLS Program, in a statement. “The test also confirmed that the amount of space available in the airlock, on the deck, and in the elevator, are sufficient for the work our astronauts plan to do.”

Shorter turnaround?

Through the Starship testing Campaign, SpaceX achieve shorter and shorter time between launches. It’s due in part to the fact that SpaceX can accomplish more every time in a way that is less destructive as well as due to work done with the FAA.

Flight 2 took place just two days later than Flight 1, Flight 3 was just 117 days later than the flight 2 as well. Flight 4 comes just 84 days following Flight 3. Watson-Morgan explained that her understanding is that SpaceX is looking to achieve the monthly launch schedule at Starbase but is aware that they’ll have to integrate the experience of prior flights into the next that could take longer time.

“Even if it’s every two to three months, that’s still quite an achievement for a test campaign and each one of these tests will buy down different risks,” Watson-Morgan explained. “For a NASA standpoint, seeing each one of those launches, we’ll get a little deeper insight into how all the engines act, how they’re performing, with respect to the ISP (specific impulse) and so, we will have that.”

When it approved the launch license modification that allowed SpaceX to launch Flight 4, the FAA stated that SpaceX provided three options for Starship launch at conclusion of mission “that would not require an investigation in the event of the loss of the vehicle.”

“The FAA approved the scenarios as test induced damage exceptions after evaluating them as part of the flight safety and flight hazard analyses and confirming they met public safety requirements,” the agency stated in an announcement. “If a different anomaly occurs with the Starship vehicle an investigation may be warranted as well as if an anomaly occurs with the Super Heavy booster rocket.”

This language, when combined with the efficiency of Flight 4 could open the possibility of a faster announcement of the Flight 5 mission.