Booster 7

History

Construction

The thrust puck for Booster 7 was spotted by a Reddit user on 29 September 2021, before being delivered to the production facility on 2 October. The forward dome sleeve was spotted on November 14.

Booster 7 stacking operations were underway as of December 27, with the NASA SpaceFlight Now stream capturing the aft section of the booster being raised in the High Bay. As of January 8, 2022 the aft LOX tank section was spotted being moved into the High Bay before the methane tank section began stacking on January 16. The Booster’s four grid fins were sighted on March 4. The next day on March 5, a new aft section design was spotted before it was rolled to the High Bay. The methane tank continued to be stacked in the Mid Bay.

While the Booster was being stacked in the High Bay, it was observed that the layout of the Composite Overwrapped Pressure Vessel (COPVs) was different to previous boosters. Older boosters  arrayed the COPVs in a ring, but on Booster 7 they were in two vertical columns. On March 10, the two sections of Booster 7 were stacked in the High Bay. Booster 7 was moved out of the High Bay twice on March 25 before being placed back in it.

Booster 7 was rolled out the launch site on March 31, being observed on its journey by Mary (BocaChicaGal) and Starship Gazer, when Cosmic Perspective observed that crews began to prepare it for being lifted.

NASASpaceFlight have documented a number of design changes to the Super Heavy booster, including:

• The thrust section has been changed to a four high stack with a non-standard ring height of 1.4m tall
• The stringers on Booster 7 have been extended further, possibly to provide additional reinforcement due to the use of Raptor 2 engines
• A new header tank design
• Pressure lines have been reduced from four on Booster 4 and Booster 5 to two.
• New aero surfaces are being installed on the Boosters, which will sit over the Composite Overwrapped Pressure Vessels. The aero covers could allow for a more efficient boost back burn, allowing the booster to save fuel and increase the payload to orbit.

Testing

Plans to move Booster 7 were delayed after it was detached from the SpaceX LR 11000 Crane on April 1, however the next day on April 2 the Booster 7 was successfully lifted and placed on Orbital Launch Pad A. The first cryogenic pressure test took place on April 4. April 8 saw Booster 7 be lifted off the launch pad, and placed on a structural test stand. An ambient pressure test took place on April 11 (observed by a friendly bird).

On April 18, Booster 7 was transported back to the production facility, being moved to the High Bay presumably to have its engines fitted. A leaked image on April 23 showed damage to Booster 7 after the downcomer pipe had been crushed. By May 6 the damage had apparently been repaired, as Booster 7 was rolled out once again from the High Bay and moved to the Orbital Launch Pad. Later during an interview with Tim Dodd that was released on July 10, Elon confirmed the damage that took place saying:

We had a slight issue with the Booster 7 test, where we collapsed part of the LOX transfer tube. So we’re going to go in and repair the LOX transfer tube […] and will probably take us a week to fix.

Preparations to fit Booster 7 with raptors were observed, with a Raptor installation platform being moved near the launch pad on May 8. Another cryogenic pressure test took place on May 9.

New preparations for removing Booster 7 from the pad commenced on May 12 when it was connected to a load spreader crane. Booster 7 was then rolled back to the production site on May 14 where it was placed into the new Mega Bay. A grid fin was connected to the booster on June 3. Elon Musk posted a photo on Twitter on June 10 showing 33 raptor engines fitted.

Booster 7 was once again rolled out to the launch site on June 23, this time with the 33 Raptor 2 engines fitted ahead of its static fire test campaign. At the launch site it was positioned between the chopstick arms of the tower, before being lifted onto the launch mount during the night. Not long after the lift, the igniters on the Raptor engines were tested with a raptor maintenance platform spotted underneath the booster during the night. Another cryogenic test was carried out on June 27.

On July 2, the official SpaceX twitter account tweeted an image showing the installed engines on Booster 7. On July 9 a SpaceX filing to the FCC was found, according to Michael Baylor’s analysis:

• After launch the Booster would perform either a partial return, or a full return and catch attempt at the launch site
• Starship would reach an altitude of 250km, before doing a powered reentry and splashing down near Hawaii
• Starlink terminals would be utilised for “high-data-rate communications”, particularly during re-entry.

An engine test was scheduled for July 11, as the test was in progress at 4:20pm local time an unexpected explosion occurred under the booster, accompanied by a shockwave and visible signs of damage, with a fire then starting on the pad. Elon Musk was asked on Twitter whether the blast was planned, in a deleted tweet he indicated that engine testing was in progress but later responded to a video uploaded by Chris Bergin with “Yeah, actually not good. Team is assessing damage.” Tim Dodd reported that the explosion was felt at MARS [Studio B] as it “shook like crazyyyyy“. Exact damage to Booster 7 at this point in time is unknown.

Follow up tweets from Elon Musk later that night indicated that the “Base of the vehicle seems ok by flashlight.”, and the following day that “Damage appears to be minor, but we need to inspect all the engines. Best to do this in the high bay.”.

On July 14 the booster was lifted off the launch mount in preparation for being rolled back to the High Bay.

Milestones

All dates & times are local unless otherwise indicated.