It’s been a busy week for SpaceX! Yesterday (Sunday, Aug. 2nd), astronauts Robert Behnken and Douglas Hurley returned from the International Space Station (ISS) aboard the same Crew Dragon spacecraft that had carried them to space two months before. With their safe return, the first crewed mission to launch from US soil in almost a decade (Demo-2) was complete, signaling that NASA has restored domestic launch capability to the US.
In all the hubbub, another major SpaceX accomplishment went largely unnoticed. This was the successful completion of a full-duration static fire test by the SN5 Starship prototype, which took place at the company’s South Texas Launch Facility near Boca Chica on Thursday, July 30th. With this milestone reached, SpaceX is moving ahead with the next major test of the SN5, the long-awaited 150 meter (~500 foot) hop test!
This successful test occurred after the company was forced to scrub multiple attempts over the past week. This was the result of Hurricane Hanna, the first storm of the 2020 hurricane season, that touched down in South Texas just days before the test took place. Nevertheless, conditions had improved by Thursday to the point that ground crews at Boca Chica were finally able to conduct a static fire test.
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It began at 03:02 pm local time (04:02 pm EDT; 01:02 pm PDT) when the single Raptor engine attached to the SN5 was ignited and burned for several seconds straight. Compared to previous tests, very little dust or debris was created by the engine and no fires broke out around the launch pad. This has boosted the company’s confidence that that SN5 is ready to take the next step and perform the first hop test with a full-scale prototype.
Two minutes later, Musk took to Twitter to announce that the test was a complete success and indicated that the path was now clear for the hop test. Based on a Notice to Airmen (NOTAM) issued on Thursday by the US Federal Aviation Administration (FAA), this test could have taken place on Sunday, with a launch window opening at 08:00 am local time (06:00 am EDT; 09:00 am PDT) and closing 08:00 pm tonight (06:00 pm EDT; 09:00 pm PDT).
Unfortunately, this attempt was scrubbed and followed by the FAA issuing a new NOTAM, which established a backup launch window that will open at 08:00 am on Tuesday, Aug. 4th, and close at 08:00 pm on Wednesday, Aug. 5th. Public notifications for Cameron County also indicated road closures in the area that began on Sunday and will last until 8:00 pm on August 4th.
The SN5 hop test will be the first flight involving a Starship prototype in 11 months, the last one involving the Starship Hopper, which made a 150 m (500 ft) hop with a single Raptor engine back in August of 2019. This time around, it will be the first flight test involving a full-scale prototype, bringing the Starship and Super Heavy launch system one step closer to making commercial launches.
It’s been a long and troubled road to get the Starship to this point. Over the past eight months, SpaceX has lost four prototypes to testing-related accidents. This has included the loss of Mk1, SN1, and SN3 prototypes, all of which experienced blowouts during the cryogenic load test. Then there was the SN4, which passed the cryogenic load test only to explode on the launch pad during the static fire test.
However, these losses were anticipated, and are a fundamental part of SpaceX’s rapid-prototyping process. By testing one iteration after another to failure, SpaceX has been able to test its Starship design to its very limits and make changes along the way. With SN5 having passed both the cryogenic load and static fire test, it is now the closest to achieving flight of any full-scale prototype.
If all goes well, SpaceX could be making a 20 km (12.5 mi) hop test using a three-engine prototype later this year. The company also has a number of design elements that they are waiting to incorporate, like the new steel alloy they want to use to build the hull. In the near future, SpaceX is likely to begin developing the Super Heavy element, the first stage booster that will no less than 31 Raptor engines providing thrust.
Small steps, small hops, and eventually, orbital flight!
Further Reading: Ars Technica