Image Source: SPadre (@SpacePadreIsle via Twitter)

SpaceX teams are actively working on building the first flight design of their Starship spacecraft, referred to as Version 1.0 Serial Number 1 (SN1) at their South Texas facility located in Boca Chica Beach, Brownsville, Texas. Musk spent the last weeks of December 2019 working alongside engineers and mechanics. He shared some details about their progress via Twitter. He wrote:

"We’re now building flight design of Starship SN1, but each SN will have at least minor improvements, at least through SN20 or so of Starship V1.0."

We’re now building flight design of Starship SN1, but each SN will have at least minor improvements, at least through SN20 or so of Starship V1.0.

— Elon Musk (@elonmusk) December 28, 2019

SpaceX will build as many as 20 flight vehicle prototypes of Starship. During the vehicles' testing process engineers will incorporate some minor changes needed towards improving it. They have been building prototypes for a year to test the stainless steel design structure and their next generation rocket engine, the Raptor.

Starhopper/Scaled down Starhopper/Starship Mk1. At Boca Chica, Texas.

Image Source: Elon Musk and @JaneidyEve

Several successful low-altitude flights with a scaled down version of Starship, called Starhopper were conducted in Texas last year. Starhopper was the first prototype, under construction outdoors. The craft was 'scaled down' unintentionally due to harsh weather conditions at Boca Chica. Starhopper's top section was hooked to a concrete base and it tipped over during a wind storm in 2019. To save time, SpaceX decided to only use the bottom half of the craft to test the Raptor engine during low altitude flights.  Read more: A look back at SpaceX's 2019 Starship Development in Texas.

The first prototype of #Starship hopper will take a few weeks to repair. 50 mph winds broke the mooring blocks late last night & fairing half was blown over.
photos 20 min ago :/ #SpaceX

Best of luck to all the hardworking @SpaceX teams. ♡ Y'all got this! pic.twitter.com/JfRX86TyyG

— Evelyn Janeidy Arevalo (@JaneidyEve) January 23, 2019

Boca Chica is a beach zone with no large buildings to block air flow. Sometimes winds coming from the ocean are very strong, can surpass 50 miles per hour. Climate in South Texas is also very humid and hot, especially near the ocean where mist with salty sand dust flows along winds. The coastline has been struck by hurricanes in the past. Musk shared that Starship SN2, the second prototype out of 20 in the V1.0 series, will be assembled inside an enclosed environment:

"Moving to an enclosed (fairly) clean room environment for SN2 in Jan, although, unlike aluminum, stainless steel welding is not super sensitive. Our main issue here in Boca is that it can get very windy, which affects weld arc & steel melt pool."

That statement also provides some insight of the quick work pace they aim for -SN2 could begin construction during January, simultaneously with SN1. Maybe all future prototypes will be assembled inside a building, some large structures can already be seen under construction at the assembly site along the road leading to Boca Chica Beach. Read more: Elon Musk shares Starship progress from SpaceX Boca Chica.

Panorama of starship construction area pic.twitter.com/N14bcUHUN4

— SPadre (@SpacePadreIsle) January 1, 2020

The Starship SN series is expected to perform higher altitude (sub-orbital) flight tests, differing from all their previous prototypes that only conducted flights under 200 meters. Musk also shared that Starship SN1's first test flight will take place in Texas, approximately 2 or 3 months from now. So, we could see the first high altitude launch, of several kilometers, take place sometime in March. This year they aim to conduct an orbital Starship flight test as well, after sub-orbital launches. 

Musk also stated that Starship's development will be focused at Boca Chica at the moment, while SpaceX’s Florida teams will focus on their Falcon 9 rocket and Dragon spacecraft. 

"We’re focusing on Boca right now for Starship & Cape is focused on Falcon/Dragon"

Which makes sense because this year, SpaceX aims to launch NASA astronauts aboard the new Dragon spacecraft on their first crewed mission to the International Space Station, from NASA's Kennedy Space Center in Florida. Read more: New SpaceX video shows what will happen during their first manned mission scheduled for 2020.