- Elon Musk has confirmed that SpaceX hopes to try "very short" launches or "hops" of a new spaceship prototype in Texas this week.
- Called the "Test Hopper," the vehicle is a prototype of a more advanced, 400-foot-tall launch system called Starship, which SpaceX is designing to send people to Mars.
- Musk also shared critical updates about Starship's heat shield, test-launch plan, construction timeline, and more.
This story has been updated with new information.
When updates about SpaceX's plans rain from Elon Musk, they tend to pour.
Such was the case on Sunday, when Musk — the rocket company's founder — opened Twitter to divulge the latest information about a roughly 40-story launch system called Starship.
The ultimate goal for the Starship system is to ferry up to 100 people and 150 tons of cargo to the surface of Mars. It's also being designed to be fully reusable, which may reduce launch costs by 10- to 100-fold (and further disrupt the launch industry).
But to prove the technologies required to get Starship into orbit will actually work, SpaceX has feverishly developed a prototype called "Test Hopper" at its launch site in southern Texas. The shiny steel vehicle can't reach orbit, and will instead just do short launches or "hops" of no higher than 16,400 feet (hence its name).
Over the weekend, following reports that SpaceX was preparing for its first hops this week, Musk took to Twitter to answer questions from his followers. In the process, he shared new details about the Test Hopper's launch testing, changes to Starship's heat shield, construction of orbital-class spaceships, and more.
Here are five of the most important things we learned.
The first hops of the Test Hopper may indeed happen this week.
On Sunday afternoon, one of Musk's Twitter followers asked if the first hops were really happening this week.
"Hopefully," Musk said in response, though he noted that there are always "many issues" when attaching large engines to rocket stages. In this case, the Test Hopper will rely on a next-generation Raptor engine, which is roughly the size of a delivery truck and can produce nearly 450,000 lbs of thrust by rapidly burning liquid methane with liquid oxygen.
"First hops will lift off, but only barely," Musk added.
Prior to Musk's comments, SpaceX also revealed a few details about the imminent test launches.
"SpaceX will conduct checkouts of the newly installed ground systems and perform a short static fire test in the days ahead," the company said in an email to Business Insider. "Although the prototype is designed to perform sub-orbital flights, or hops, powered by the SpaceX Raptor engine, the vehicle will be tethered during initial testing and hops will not be visible from offsite."
On Tuesday, Cameron County (where SpaceX's Texas launch site resides) posted an online notice. The notice suggests Test Hopper will test-fire and possibly launch for the first time on Wednesday, Thursday, or Friday between 11 a.m. and 5 p.m. EDT.
SpaceX ditched the Test Hopper's damaged nosecone.
Activity at SpaceX's Boca Chica site began to boom in November. Residents in the area said crews were working almost 24/7 to weld together a structure that at first appeared to be a water tower. Later, it became apparent that they were building a rocket ship: the Test Hopper.
Musk confirmed the vehicle's construction in December. A few weeks later, he shared a rendering of what it'd look like, followed by a photo showing that SpaceX had completed construction on the outer hull.
But soon after, gale-force winds in Texas blew the nosecone over and damaged it. Musk initially said it'd take a few weeks to repair, but he revealed on Sunday that the nosecone is now in the scrap pile.
"We decided to skip building a new nosecone for Hopper. Don't need it," Musk tweeted.
A full-scale Starship is under construction.
In his recent tweets, Musk also addressed photos of another vehicle currently under construction at SpaceX's facility in Boca Chica, Texas.
"What you see being built is the orbital Starship vehicle," he said.
Musk previously suggested that SpaceX would finish building a taller, orbit-capable Starship prototype " around June." That rocket ship would have "thicker skins (won't wrinkle) & a smoothly curving nose section" compared to the Test Hopper, he added.
On Sunday, Musk said that the orbit-capable Starship would be "full size," though he didn't say whether he was referring to the roughly 180-foot-tall Starship spaceship, or to both the spaceship and its 220-foot-tall Super Heavy booster. (The booster is the part of the system that would help heave a Starship into orbit and conserve its fuel supply.)
If SpaceX builds both parts concurrently, a mirror-polished rocket ship the size of a 40-story building may appear in south Texas this summer.
Starship's heat shield has changed radically — again.
On Sunday, Musk shared a video (above) of heat-shield tiles passing a "full duration" test.
These tiles are the most recent iteration of the technology SpaceX is developing to cool and protect Starship as it re-enters Earth's atmosphere and attempts to land. Such protection is necessary because spacecraft plow through Earth's atmosphere at roughly 25 times the speed of sound when they return, creating scorching-hot plasma that can vaporize steel.
Previously, Musk had said that Starship's heat shield would "bleed" rocket fuel from tiny pores in the spaceship's skin, thereby cooling it down. But a full "bleeding" system would have faced a number of unprecedented challenges, since clogged pores could lead to the destruction of Starship.
Musk's new video suggests that SpaceX has decided to go with a combination of hexagonal tiles and sections of Starship that'd transpire fuel.
"Hexagonal tiles on most of windward side, no shield needed on leeward [back] side, transpiration cooling on hotspots," Musk said, later adding: "Transpiration cooling will be added wherever we see erosion of the shield. Starship needs to be ready to fly again immediately after landing. Zero refurbishment."
In effect, Musk was hinting at SpaceX's iterative test plan for Starship: Build one with a tile-based heat shield, get it into orbit, land it, then examine the tiles for wear. In the spots where tiles look especially battered by 2,000-degree-Fahrenheit plasma heating, engineers will try to implement the "bleeding" cooling system.
Musk wants to launch Starships in Florida, too.
SpaceX has not yet been clear about where, exactly, the company plans to build the Starship vehicles.
In April, LA mayor Eric Garcetti approved the company's plan to build Mars vehicles at the Port of Los Angeles. But that plan was made when SpaceX was attempting to manufacture large carbon-fiber structures. So there's now doubt about whether and how SpaceX might use the LA site going forward.
That uncertainty increased on Sunday, when a Twitter user asked Musk where Starship's first orbital flights would occur.
"Working on regulatory approval for both Boca Chica, Texas, and Cape Kennedy, Florida," Musk said. "Will also be building Starship & Super Heavy simultaneously in both locations."
Transporting sections of a roughly 30-foot-wide, 400-foot-tall vehicle from LA to launch sites in Texas or Florida would not be cheap or easy.