SpaceX is building and launching prototypes of Starship — a reusable launch system designed to send people to the moon and Mars — from Boca Chica, a site at the southern tip of Texas.

But that's not how SpaceX originally proposed to use the site. When it got approval in July 2014, the rocket company said it'd build a commercial spaceport to launch Falcon 9 and Falcon Heavy rockets.

The Federal Aviation Administration has reviewed SpaceX's new plans for the site, and the government regulator has published several "written reevaluation" documents following inquiries from Business Insider.

Though SpaceX has turned Boca Chica into a Starship skunkworks, the FAA believes the company is operating within bounds of its original assessment in terms of safety and environmental impact.

In addition, the documents describe a three-phase development plan for Starship over the next two or three years. The pages also contain graphic layouts of planned launch-site construction.

Visit Business Insider's homepage for more stories.

Update (1:40 p.m. ET on September 9, 2019): The FAA on Friday posted the two documents that it'd emailed to Business Insider, as well as two related files, to its website.

New regulatory documents sent to Business Insider, and later published online, provide a glimpse into SpaceX's plan to develop a disruptive new rocket system over the next two to three years.

Every day at Boca Chica — a hot, humid, narrow, and sandy strip of clay at the southernmost tip of Texas — SpaceX workers toil over the rocket company's big project, called Starship.

An illustration of SpaceX's Starship vehicle on the surface of the moon, with Earth in the distance. Elon Musk/SpaceX via Twitter

Elon Musk, the company's founder and CEO, envisions the vehicle as a shiny steel two-stage launch system that may stand nearly 400 feet tall and reduce the cost of access to space by a factor of 100 to 1,000 by having fully reusable hardware.

It may be capable of sending massive payloads into orbit, humans to the moon and Mars, and scores of passengers around the world in half an hour.

Read more: SpaceX is eyeing these 9 places on Mars for its first Starship rocket missions

The new regulatory reviews, which the Federal Aviation Administration released this week, came after the company substantially changed its vision for Boca Chica. Business Insider was sent PDFs of two files via email from an FAA representative after inquiring about their status.

The FAA's main document is a 23-page "written reevaluation," finalized in May 2019, which addresses the potential impacts of SpaceX's new plans. It's accompanied by a separate five-page addendum, finalized in August 2019, that addresses a large brush fire the company accidentally started during an experimental launch in July.

Following publication of this story, the FAA published the same two files to its website as well as two other written reevaluations, one from November 2014 and another from October 2017.

The documents followed a years-long environmental assessment that the FAA, SpaceX, the state of Texas, and local authorities hammered out by July 2014. That original corpus of more than 1,600 pages is an exhaustive (though now dated) official review of SpaceX's site that the FAA uses in part to approve or deny the company's launch licenses there.

The latest documents covers SpaceX's shift away from developing a commercial spaceport and confronts its new reality as a skunkworks for Starship.

The FAA reevaluated SpaceX's site after a big change in the company's plans

A May 2014 rendering of a Falcon Heavy rocket at SpaceX's South Texas launch site near Boca Chica Beach. The company ultimately changed its plans and design for the facility. SpaceX via FAA

SpaceX's site is located about 20 miles east of Brownsville, a few miles north of the US-Mexico border, and about half a mile from Boca Chica Beach.

The company originally agreed to build a commercial spaceport by spending about $100 million on the effort, including some $15 million worth of incentives from county and state governments. Space missions were supposed to start launching by the end of 2017, with up to a dozen trips each year.

Falcon 9 and Falcon Heavy rockets were to take off from a large launchpad equipped with a flame trench (to redirect hot rocket exhaust), a 250,000-gallon deluge system to flood the pad with water (to suppress sound and cut fire risk), lightning protection towers, and other safety features.

Yet before SpaceX could do anything, it had to go through a gauntlet of filing an environmental impact statement with the FAA. The company spent years studying the site and meeting with local, state, and federal officials.

The resulting EIS captures the potential environmental impacts to the area, and it was finalized in July 2014. For a variety of reasons, though, SpaceX's construction in the area slowed to a crawl almost as soon as it began.

Read more: Elon Musk is building SpaceX's Mars rockets in a tiny Texas hamlet. But getting them off the ground there may be harder than he imagined.

By May 2018, Musk said that SpaceX was dropping its commercial-spaceport plan and instead dedicating the site to building and flying Mars rocket-ship prototypes. The company is now using different launch vehicles (Starship prototypes), different fuel (methane instead of RP-1, a rocket-grade kerosene), and a new rate of launches, as well as switching up construction projects and other details.

A comparison of SpaceX and NASA rocket systems. Yutong Yuan/Samantha Lee/Business Insider

This shift in plans prompted the FAA to step in, reevaluate, and square these new details with the original EIS to see whether there'd be any unaddressed public-safety threats or environmental damage.

The document neatly lays out the crux of SpaceX's experimental test program:

"SpaceX remains committed in its mission to colonize Mars. To achieve this mission, SpaceX is developing a new rocket called the Starship and Super Heavy. A key part of the mission is developing the Starship spacecraft. In order to fully develop the vehicle, an experimental test program is needed. The proposed experimental test program involves testing a spacecraft — the Starship — which would serve as the second stage of the rocket. The objective of the experimental test program is to perform a suborbital space flight from the Texas Launch Site."

Despite SpaceX's substantial evolution of its Boca Chica site, the FAA found few major deviations, at least from an impact standpoint — so it determined a new (and very arduous) supplemental EIS process was not required. If anything, the documents suggest SpaceX's new Starship development would decrease the company's disruption in the area, including noise levels, wildlife effects, and wetland impacts.

"The modifications remain entirely within the property boundary and project area described and analyzed in the 2014 EIS," the FAA said.

SpaceX built its first launch pad within about 1.5 miles, or 2.4 kilometers, of a nearby community called Boca Chica Village. Despite this, and the company's inadvertent brush fire coming within a few thousand feet of the hamlet, the FAA determined "there were no public safety concerns" due to a "pre-established safety zone."

"All mitigation efforts due to the brush fire were controlled by US Fish and Wildlife Fire Management and the Brownsville Fire Department," a SpaceX representative told Business Insider. "The determination that this fire presented no risk to public safety was made by those agencies."

Though the FAA can request public feedback to incorporate into its written reevaluations, a representative for the regulator told Business Insider the document "is final" and "will not have any comment period."

The documents also outline a 3-phase Starship development program

A "Phase 1" construction layout for Starship. (The underground water tank was swapped for three above-ground tanks.) FAA/SpaceX

The main FAA document, which was finalized May 21, contains figures on the amounts of methane, oxygen, water, helium, and other "commodities" SpaceX thinks it needs for Starship testing in Texas. (The company has since built a second Starship development site in Cocoa, Florida.)

The document also lays out a three-phase test program, which it says "would last around 2 to 3 years":

Phase 1 : Tests of ground systems and fueling, a handful of rocket engine test-firings, and several "small hops" of a few centimeters off the ground. The document also includes graphic layouts, like the one above, showing the placement of water tanks, liquid methane and oxygen storage tanks (Starship's fuels), and other launch pad infrastructure.

: Tests of ground systems and fueling, a handful of rocket engine test-firings, and several "small hops" of a few centimeters off the ground. The document also includes graphic layouts, like the one above, showing the placement of water tanks, liquid methane and oxygen storage tanks (Starship's fuels), and other launch pad infrastructure. Phase 2 : Several more "small hops" of Starship, though up to 492 feet (150 meters) in altitude, and later "medium hops" to about 1.9 miles (3 kilometers). Construction of a "Phase 2 Pad" for Starship, shown below, is also described.

: Several more "small hops" of Starship, though up to 492 feet (150 meters) in altitude, and later "medium hops" to about 1.9 miles (3 kilometers). Construction of a "Phase 2 Pad" for Starship, shown below, is also described. Phase 3: A few "large hops" that take Starship up to 62 miles (100 kilometers) above Earth — the unofficial edge of space — with high-altitude "flips," reentries, and landings.

A "Phase 2" layout for Starship's launch site from the Federal Aviation Administration's written reevaluation. FAA/SpaceX

SpaceX's representative said the company had officially ended Phase 1 and was in the midst of Phase 2.

Phase 1 centered on SpaceX's first Starship prototype, called Starhopper. Sections of the shiny steel vehicle were first spotted in social-media photos posted from Boca Chica in late 2018.

The vehicle was mostly completed in February, though its nose cone was quickly blown off by powerful Texas winds. SpaceX decided the nosecone wasn't needed and launched Starhopper as a stubby version of its former, rocket-shaped self. The vehicle flew on short tethered flights in April, a roughly 6o-foot, or 20 meter, "hop" in July, and a flight in August that soared the vehicle to about 490 feet, or 150 meters — a key step described in Phase 2.

Read more: The FAA made SpaceX boost its accident insurance 33-fold, to $100 million, before Starhopper's last launch. Here's why.

During that latest and final flight in August, Starhopper also translated across its launch site and landed on a new concrete slab that matches the layout of the Phase 2 Pad.

Construction of the Starship Mk1 prototype in Boca Chica in April. Dave Mosher/Business Insider The FAA document says Phase 3 — SpaceX's most ambitious near-term goal in Texas — had not yet begun, adding that its exact details would depend on how the company's first two phases went.

"SpaceX would be required to submit data and information to the FAA so the FAA can conduct another environmental review before issuing any new or modified licenses or permits to conduct these operations," the FAA wrote of Phase 3.

It's unclear whether the rough Phase 3 plan in the FAA document is still valid. SpaceX is known for rapid shifts in development, and when asked about the phase, the company said only that it was "working directly with FAA to maintain environmental compliance as our testing plans develop."

Phase 3, however, is likely now more ambitious. Based on tweets from Musk, it may entail launching a new, roughly 180-foot prototype known as Starship Mark 1 (Mk1) a dozen miles high and beyond this fall.

"Aiming for 20km flight in Oct & orbit attempt shortly thereafter," Musk tweeted on August 28.

Musk added that he would provide an update on the overall Starship development program on September 28. Previously, he said he would deliver that presentation from Boca Chica, Texas — possibly to do so with a fitting backdrop.

"Starship Mk 1 will be fully assembled by that time," he said.

Have a story or information to share? Send Dave Mosher an email or consider more secure communication options listed here.