SpaceX is really coming along with its development of the Starship and Super Heavy launch system. After repeated delays caused by structural failures (aka. explosions), the company got back on track late in April when their fourth prototype (SN4) passed the crucial cryogenic load test. This was followed by a successful static fire test on May 4th, followed by a second static fire test the next day.
And, after being scrubbed three times since last Friday (May 15th), SpaceX conducted the third static fire test with the SN4 on Tuesday, May 19th. Unfortunately, an unexpected fire near the base of the rocket caused the prototype to get a bit scorched and caused some internal damage. However, the prototype survived and is back in working order, which means SpaceX is moving ahead with more tests in preparation for a full-scale launch.
The fire in question occurred immediately after ignition, apparently due to a methane line bursting because of the sudden change in pressure. The engine continued to burn for a few more seconds and shut down as planned, but the fire continued and managed to ignite insulation wrapped around the rocket’s launch mount. Luckily, the remotely-controlled water jets positioned around the pad managed to suppress the fire before long.
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In addition to scoring the hull, the fire is believed to have caused damage to the prototype’s wiring, which resulted in the ground crews partially losing control of it. Fortunately, the electrical damage did not prevent ground crews from safely offloading its remaining propellant and vent the gases building up inside the cryogenic tanks, which preventing the SN4 from bursting like its predecessors.
This third static fire test was also significant because it was the first test involving an integrated SN20 Raptor engine, which replaced the SN18 Raptor engines that were used during the two previous test firings earlier this month. Nevertheless, the anomaly and the resulting fire that occurred have complicated SpaceX’s planned testing schedule, which has suffered several setbacks so far this year.
For starters, it delayed attempts to inspect and repair the damage to the prototype for two whole days (until Thursday, May 21s) as well as SpaceX’s planned hop test. According to recent filings with the Federal Aviation Administration (FAA), which were issued before this latest test, SpaceX hoped to conduct the 150 m (500 ft) hop test this week.
While the FAA has not issued a license yet, they did issue a Notices to Airmen (NOTAMs) on May 18th, advising that pilots avoid the airspace over Boca Chica up to an altitude of 4875 m (16000 ft). The notice went into effect on Thursday, May 21st, and ran from 12:00 p.m. to 06:00 p.m. local time (10:00 a.m. PDT to 04:00 p.m. PDT). While the delays with the test and the fire have pushed this back, its clear SpaceX and the FAA are
The NOTAMs issued this past week by the FAA suggest that they are close to issuing an official license for the hop test. It’s clear that SpaceX also wants to move ahead with the testing of a full-scale prototype, effectively picking up where they left off with the Starship Hopper. Back in August of 2019, this single-engine prototype achieved a maximum altitude of 150 m (500 ft) during its final hop test.
So while this test didn’t quite go as planned, there are no shortages of silver linings, not the least of which is the way that such anomalies allow engineers to identify and fix unforeseen issues with the prototypes. Speaking of which, this is what SpaceX will be doing in the meantime, looking over the data from the static fire test to determine the exact cause of the fire cause and rectify the issue.
It is also a foregone conclusion that the ground crews will not be installing highly flammable insulation to the launch mount again.No indication has been given yet as to what the next steps are, but NASA SpaceFlight’s own Michael Baylor has indicated that road closures have been announced for May 28th, 29th, and June 1st around Boca Chica.
This suggests that testing will resume by the end of the month, and Baylor further ventures that SpaceX will opt for another static fire test to make sure they’ve resolved the issue that caused this one. Better safe than sorry, after all. And while we might have to wait a little longer for the much-anticipated hop test (and the orbital flight that will follow), the progress we’ve seen so far cannot be denied.
Musk has always been known for being optimistic about his timelines, but he always seems to get the job done sooner or later!
Further Reading: Teslarati