SpaceX assembling orbital Starship

 From Teslarati

SpaceX has begun rapidly assembling the first orbital Starship prototype and the Super Heavy booster set to launch it isn’t far behind.

SpaceX’s Boca Chica, Texas rocket factory seemingly turned a corner in early July as sections of Starship 20 (S20) began to pop up around the site. Though parts labeled Starship “SN20” first appeared as far back as March 2021, the only unequivocal work on SpaceX’s first purportedly orbital-class Starship began in mid-June with the integration of the first engine section with mounts for six – not three – Raptors.

However, in line with SpaceX’s strict focus on maximizing the speed of Starship development and shortening the path to orbit, the company has frequently built Starship hardware before firmly assigning that hardware to any given ship, booster, or tank. In other words, until SpaceX actually begins stacking multiple completed rocket sections, there’s always a degree of uncertainty about the fate of any given ring, dome, or tank barrel. With Starship S20, that process began earlier this month and Super Heavy Booster 4 is likely to follow suit within the next few days – if it hasn’t already.

Since SpaceX unceremoniously rolled Starship prototype SN16 to an empty lot in mid-May, the company didn’t stack a single Starship part until the first week of July – unusual after a frenetic seven months spent building, qualifying, and launching Starships SN8, SN9, SN10, SN11, and SN15 and testing test tanks SN7.2 a nd BN2.1. Around the same time as Starship SN15 became the first prototype to successfully complete a high-altitude test flight and land in one piece, news broke that SpaceX was striving to perform Starship’s first orbital test flight with Ship 20 (S20) and Booster 3 (B3) as early as July.

Eventually, Booster 3’s orbital launch assignment shifted to Booster 4 as it became clear that the former prototype wasn’t meant to fly, but Starship S20 remained. More likely than not, the almost two-month gap between Starship SN16’s instant retirement and the start of the next flightworthy prototype’s assembly can be explained by the significant changes, upgrades, and undecided design decisions required to jump to S20.

Two weeks after the first stack, Starship S20 is already approximately half-assembled and the last section of the vehicle’s tanks is almost ready for installation. What could be Starship S20’s nosecone is also in the late stages of assembly, though SpaceX has yet to even attempt to fully cover a nose in heat shield tiles and getting that process right could take an attempt or two.

Musk has emphasised that there will probably be several mishaps along the way before Starship orbital flights work.  In the first attempt to get Starship orbital, the booster will try to make a soft landing in the sea off Boca Chica,  and Starship will splashdown off Hawaii.  We're so used to SpaceX reusing its rockets that the apparent waste is actually quite shocking, but I expect SpaceX thinks that things could go wrong, possibly badly wrong, and doesn't want to completely destroy its Boca Chica base.   The Super Heavy booster and Starship itself are far too large to land on the drone ships that SpaceX currently uses for its Falcon 9 boosters, so that option is out.  It says a lot about how SpaceX has changed space paradigms that we should be surprised that the spaceships  from the first orbital Starship launch should be dropped into the sea, but of course that's exactly how all other rocket manufacturers still operate.

If the development of orbital Starship seems unbearably slow, that's because we are watching it happen in front of us, day by day.  Musk only announced the stainless steel Starship in January 2019, two and a half years ago.  By contrast, NASA's SLS was announced in 2011, uses old technology, and hasn't flown yet.  Oh, and when it does, the booster will be dumped in the ocean.  Plus each Starship launch will cost roughly $2 million while each SLS launch will cost roughly $1.5 BILLION.

Starship to take over Starlink launches

 Here, I talked about how Starlink and Starship were linked: Starlink would provide the cash to help build Starship and Starship would be so big it could launch the thousands of satellites needed to get the Starlink's satellite constellation working.  Prophetic!  Remember, you read it here first (2017).

Now, Musk has announced that Starship will take over Starlink launches, replacing Falcon 9 in this rôle.

Since dedicated Starlink launches began in May 2019, Musk, COO and President Gwynne Shotwell, and a few other SpaceX officials and executives have made it clear that the company would ultimately transition the task of launching and maintaining the Starlink constellation from Falcon 9 to Starship. Barring major surprises, Starship is being designed to be fully and rapidly reusable from the ground up, nominally making the system far cheaper to launch.

After Musk announced a radical redesign that replaced carbon composite structures with simple steel, Starship may even be far cheaper to build than Falcon 9 or Falcon Heavy – despite being several times larger, heavier, more powerful, and more capable. Despite its relative shortcomings, though, Falcon 9 has become an extraordinarily reliable and available workhorse for SpaceX and has completed 28 operational Starlink launches – delivering ~1670 satellites to orbit – since November 2019.

However, while Falcon 9 has done and continues to do an extraordinary job of routinely launching satellites and astronauts, Starship promises to blow it out of the water. It might be several years before Starship is deemed safe and reliable enough to launch humans but SpaceX could feasibly start launching Starlink satellites on the rocket almost as soon as it begins orbital flight tests.

Thanks to the low cost of each Starlink satellite, likely now around ~$250,000, it would be surprising if SpaceX didn’t include at least a few dozen satellites in the early phases of orbital Starship flight tests – even if success is far from guaranteed. At some point, though, and perhaps quite quickly, Starship will safely make it to orbit, reenter, and touch down beside a Super Heavy booster a few times in a row, effectively demonstrating fitness to launch (uncrewed) payloads.

It could take a bit more proof to convince paying customers with satellites worth tens to hundreds of millions of dollars to entrust launch contracts to Starship but SpaceX itself – likely to be the builder and owner of the world’s largest satellite constellation for the indefinite future – has more flexibility to tailor its appetite for caution. With the capabilities Starship could feasibly offer, SpaceX might also be hard-pressed to just sit and wait.

[Read more here]

The first test flight of Starship and Super Heavy will prob'ly take place in July, though SpaceX won't try to land either vessel for re-use--both will splash down into the sea.  Could the first launch of a few Starlink satellites on Starship happen before the end of this year?  At $2 million per launch, Starship will be just 4% of the cost of a Falcon 9 launch, but will be able to launch 400 satellites at a time instead of just 60, cutting the effective launch cost of each satellite by 2 orders of magnitude.

Starlink will provide a truly global high-speed internet service, and it will change the world as well as making SpaceX the sort of cash needed to build an inter-planetary space fleet.  

The plunging cost of lifting a kilogram to orbit won't just change space.  It will change the Earth too.

Source: Neopork

First successful flight of Starship

 

SpaceX has successfully launched and landed Starship, without it blowing up.  It wasn't perfect: there was a methane fire after landing (soon extinguished); the rocket appears to have skipped a metre or so when it landed; and one of the Raptor engines appeared not to ignite.   

All the same, it was a magnificent achievement.  Remember, everything about this rocket is new technology: the methane Raptor engine; the use of steel as a construction material; and the "belly-flop" landing manoeuvre.  And they all worked.  In development, SpaceX started with the Starship upper stage first, because this was the hardest  part of the two-stage Super Heavy booster + Starship combo. The success of Starship brings the colonisation of Mars much closer, because SpaceX knows all about making re-usable boosters.  That's what the Falcon 9 rocket is.  

There is much further to go.  To make Starship truly re-usable, the ceramic tiles used as a heat shield must be easily replaceable.  Starship must demonstrate that it can return to Earth at orbital velocity without burning or breaking up.   But all the -out-there concepts that SpaceX pushed have been shown to work, at a cost 1 thousandth of current rockets, even before they are re-used.

Starship will change everything about space and a great deal about Earth.  Technology responds to need.  As Musk says, the colonisation of Mars will drive a forcing function in technologies, like genetic engineering, air and water purification, construction techniques, AI, to name just a few.  The most obvious right now is high speed internet access round the world via SpaceX's Starlink.  Here's an interesting article about that from The Economist.  Starlink is being used to fund Starship, but it's also being advanced by Starship because Starship will cut launch costs so much.

Here's The Guardian's take on the launch:

Success came on the 60th anniversary of the flight of first American in space, Alan Shepard. And it capped a stunning two weeks of achievements for SpaceX: the launch of four more astronauts to the space station for Nasa, the nation’s first night-time crew splashdown since the Apollo moonshots, and a pair of launches for its mini internet satellites.

Less than a month ago, Nasa chose SpaceX’s Starship to deliver astronauts to the lunar surface in the next few years. The $3bn contract was halted last week, however, after the losing companies – Jeff Bezos’s Blue Origin and Dynetics – protested against the selection.

And here's a video of the whole sequence from launch to landing, with however the sections where signal from the rocket was lost omitted:

Starship SN8 ready to fly

 Over the last few weeks, SpaceX has been testing various prototypes of its Starship spaceship.  Today, it's assembled a working version ready for a hop test to 150 metres.  If that works, and they may do several hop tests to suss out all the problems, then they'll do a flight to 15 kms.  

(Picture from SPadre)

On its way down from the 15 km 'hop', the Starship will test out the 'skydiving' manoeuvre, using its flaps to slow itself down, before turning vertical (tail first) to land retro-propulsively.  This will be a key test, because SpaceX is relying on this technique to bleed off the very high velocities that will happen on re-entry from orbit.  If Starship cannot stand up to the stresses of a 15 km 'hop', then it will be unable to handle re-entry.

If the 15 km flight is successful, then Musk has said that the next step is orbit.  I don't think  Starship will be able to fly to 160km and still have enough fuel for a retro-propulsive burn, and the first stage (Super Heavy) has only just started construction, so Musk may just mean a flight to the Kármán line (100 km above the Earth) which is the conventionally accepted definition of where space begins.  But Super Heavy may be finished early next year, and genuine orbital flight will begin.    For faster re-entry from orbit, Starship will need a heat shield made of ceramic tiles and this will be when they start testing them.

If this works, it means that regular launches with payload will start soon after.  In a video from the Mars Society's annual conference, Musk hinted at a new timetable for Mars, with unmanned flights starting in 2024, instead of 2022.  (Mars is in opposition in December 2022 and January 2025) But if Starship has proved itself be safe, we may yet have crewed flights in late 2022. Starship is so cheap that the fleet heading to Mars could take 6 or 8 cargo Starships as well as 3 or 4 crewed ones.  

We shall see.  The probability is high that something will go wrong, delaying the whole timetable.  But I hope it doesn't.  I want to see the vids as the first humans on Mars open the hatches and look out on the red planet's surface.

Starship's first 'hop'

SpaceX's Starship is new technology.  Its 'Raptor' engine burns cryogenic methane, not the purified version of jet fuel most rockets burn.  It was developed by SpaceX from scratch.  And Starship is built from stainless steel, not carbon-fibre composites, like most other rockets.

So there have been pauses for running repairs on the road.  Although the first cutback version of Starship, Starhopper, 'hopped' 150 metres, demonstrating the efficacy of the Raptor engine, all subsequent tests of versions of the Starship failed.

Until now.

The methane and liquid oxygen is held at 7.5 bars (i.e. 7.5 times the pressure of the atmosphere at sea level), and each tank tested (bearing in mind that they were made of a novel aeronautical construction material) sprung leaks, or exploded, or, in one case, imploded.  But with each failure, SpaceX learned something.  And yesterday, a real Starship, though without its nose-cone and fins, but still nine storeys tall, and with a steel cube to simulate the weight of a payload, lifted off from the company's base in Boca Chica, Texas, and 'hopped', reaching 150 metres altitude.

Of course, this is a long way from reaching Mars.  All the same, it is a huge step forward.  SpaceX has demonstrated that rocket ships can be built from steel. And can take off.  And land again.  The next step will be higher hops, and then testing of a full version of the spaceship, with a full complement of Raptor engines, flying to 20 km above the Earth, and trying to land again using the famous skydiver or belly-flop technique to burn off orbital velocity.






This is a prodigious achievement.  SpaceX only pivoted away from carbon-fibre composites to steel in December 2018.  Compare this swift development to the sluggish, even glacial, pace of conventional space companies and bureaucracies.

Stainless steel is about 3% of the cost of carbon-fibre composite, withstands both cryogenic temperatures and the 1500+ degrees C of re-entry.  Musk has stated that each Starship will cost just $5 million, and each launch of the Starship/Super Heavy combination under $2 million.  This compares with NASA's SLS (Space Launch System) of $1.5 BILLION  per launch.  Starship will lift 150 tons or 100 passengers to LEO (low Earth orbit).  This is a cost per kilogram of $13, compared with the cost, until SpaceX broke open the monopoly of dinosaur space companies, of $22,000/kg.   0.06% of the previous cost. 0.06%!!!!

Musk has stated that the really hard part of the whole process of constructing Starship and its booster Super Heavy is creating the assembly line that will build them. He's well on the way to doing this.  Already there is another prototype, SN 08, already close to completion.  It's being built of a slightly different steel alloy, as SpaceX continues to experiment and improve.  Starhopper took 8 months to build.  The latest versions of Starship seem to take 3 or 4 weeks.  The assembly line is speeding up.

Musk has said that he plans building 100 Starships a year.  He wants to send the first uncrewed Starships to Mars in late 2022, when Mars is in opposition to the Earth (in "orbit sync" as he pithily describes it)  The original plan was to send 2 cargo Starships in 2022 and 2 cargo and 2 crewed ships in 2024 to Mars.  But that was when the Starships would be constructed from carbon-fibre composites, and would be 10 times as expensive as the stainless steel versions will be.  Does that mean 20 cargo ships in 2022, and another 20 in 2024?  Or am I being overambitious?  Other SpaceX spokesmen have said that the first batch of Starships will be used as temporary habitats for the first settlers, in other words, they weren't going to return to Earth.  Only with subsequent missions would Starships return, because of the time that would be needed to make propellant on Mars to fuel their return journey.

Extraordinary.  Watch the video.  This is it—the first critical step on the road to making mankind multi-planetary.  I hope I live to see the first boots on Mars in 2024.

SpaceX's Mars timetable

Starships at Mars Base Alpha

Elon Musk has confirmed the 2022 cargo and (late) 2024 crewed expedition dates to Mars.

From the Orlando Sentinel:

Falcon 9 is a means to an end, for Elon Musk, and while the rocket that just helped transport astronauts to the International Space Station celebrated its 10-year anniversary on Thursday, Musk is keeping his eyes on the prize with Starship.

Musk took to Twitter to reiterate the company’s plans for the next-generation space vehicle and its timeline to get to Mars.

Responding to questions on the social media platform, Musk confirmed SpaceX plans to get Starship on an uncrewed mission to the fourth planet from the sun by 2022 and with humans by 2024.

“Starship is the key to making life multiplanetary & protecting the light of consciousness,” Musk wrote.

He also figures that it will take about 25 years, or roughly 12 transfer windows - when Mars and Earth are in the right position to make the trip economical - for whatever presence is on Mars to be self-sustainable, not relying on support from Earth. 

Musk has previously stated his belief that the human species needs to branch out and colonize on other planets.
“We’re faced with a choice. Which future do you want? Do you want the future where we become a space-faring civilization and are in many worlds and are out there among the stars or are forever confined to Earth? And I say it’s the first, and I hope you agree with me," Musk said in a speech last September to SpaceX employees at the company’s testing site in Boca Chica, Texas.

“The reality is as far as we know this is the only place at least in this part of the galaxy, or in the Milky Way[as a whole], where there is consciousness and it’s taken a long time for us to get to this point,” Musk said.

On Wednesday, in response to a dire tweet about the eventual demise millions of years from now of the Earth at the hands of the sun, Musk tweeted, “That’s when all life on Earth will be boiled off. What matters is how long civilization is capable of making the jump to Mars. This could be a very short period of time measured in decades. It took 4.5 billion years to get to this point & civilization isn’t looking super stable.”

This has been my estimate of the timetable for over a year now, with minor tweaks:

H1 2020: Tests to 20+ kms altitude. [Now delayed till July 2020]

End 2020: Full stack (i.e., Super Heavy booster plus Starship) operational.  First orbital flights of the Starship.

Early 2021: First commercial customers (for satellites), launches of Starlink constellation

Late 2022: Uncrewed mission to Mars (Mars is in opposition in December)

2023??: First commercial space station.  Launched on Starship, built by non-SpaceX companies—or maybe even by SpaceX  [Not part of SpaceX's plans]

2023: 'Dear Moon' circumlunar expedition

2024: Moon Base Alpha [Depends on NASA]

Late 2024/Early 2025: Crewed mission to Mars  (How many ships?  Here's my analysis)

Early 2027: Second expedition to Mars.  Return of at least one Starship.  

2029: Third expedition to Mars.  Martian population reaches 300.  If Starship works, SpaceX will start designing even bigger rockets, capable of carrying more than 100 passengers, so Mars's population in 2029 could be more than 300.  Return of some Starships.

A city on Mars

Source: Inverse

A while ago, Elon Musk stated that creating a self-sustaining city on Mars would cost between $100 billion and $10 trillion, and that at a minimum, it would require 1 million tons of cargo, which means that it will have to cost as little as $100,000 per tonne to ship cargo to Mars, if this city is to be feasible.

So, let's redo the sums.  Musk has said that the cost per launch including all elements (fuel/depreciation/sunk costs) of the Starship plus its booster will be $2 million, provided both Starship and Super Heavy are fully re-usable.   According to Wikipedia, the weight of the propellant (methane plus oxygen) needed to fill Starship's tanks is 1,200 tonnes.  Each Starship will be able to lift around 150 tonnes to LEO (low earth orbit).  So that would mean that 8 launches of Starship's tanker version would be needed to provide enough propellant for one journey to Mars.  This means the cost of just getting enough propellant into orbit for a Mars mission will be $16 million.

However, the first two fleets of Starships sent to Mars won't return.  They'll be useful as habitats while surface habitats/domes/caves are built, but in any case, there won't be enough propellant to bring them all back.  Here, I estimate that 3-5 Starships will be needed just to bring the generation equipment (KRUSTY nuclear generators, solar panels and wind turbines) needed to produce the electricity to make the propellant to send one Starship home.  Each expedition will bring more generators, so the ratio of ships able to return home will rise each time.  If half the ships contain cargo or passengers, and the other half power generation equipment, it will take something like 10 expeditions, or 20 years, for enough spare generating capacity to exist on Mars to send the whole fleet of 10 ships home.  Maybe, that time line can be improved, because I'm sure colonists will quickly start making their own wind turbines and solar panels and KRUSTY nuclear generators.  All the same, in all likelihood, for the first decade or so, only some of the ships sent to Mars will return. 

Musk has said that the capital cost of each Starship will be $5 million, which won't be spread over many launches for the Mars fleet, because in the beginning they'll only be used once.  So the total cost for each ship going to Mars will be $16 million + $5 million, or $21 million.  At 150 tonnes payload, that works out to $140,000 per tonne.  Still 40% too high. 

Yet there is a very steep learning curve here.  SpaceX chose a totally unexpected material to build Starship and Super Heavy—stainless steel.  They've had to learn how to build tanks that don't rupture, a body that doesn't collapse under its own weight (the steel is just 4 millimetres thick), structures that hold up to the stresses of launch and re-entry, the Raptor engines that burn methane rather than paraffin (kerosene).  These are all totally new technologies. 

To cut costs, production has to be automated.  Musk has stated that the difficulty lies not in building one Starship (!), but in creating an assembly line that will build hundreds of Starships, efficiently and cheaply, as well as hundreds of the Raptor engines.   Building an efficient assembly line, he maintains, will be 10 times as difficult as building one Starship.  We've never had a rocket assembly line before.  Talk about a learning curve!

Perhaps the biggest cut in costs per tonne has yet to come.  Each increase in the size of the rocket causes an exponential increase in the load it can lift.  Falcon 1 (with one Merlin engine) could lift 180 kg to LEO.  Falcon 9 (with 9 Merlin engines) can lift 15,600 kg (and that's re-using the booster).  Starship's booster, Super Heavy, will lift 150 tonnes (150,000 kgs) using 25-37 Raptor engines.  Raptor engines have twice as much thrust as the Merlin, so that's equivalent to 50-74 Merlin engines.  The ratio of payload in tonnes to number of engines goes from 0.18 →1.73→2.4.  Each increase in the size of the rocket results in a more than proportionate increase in payload, and therefore a fall in cost per tonne.  Musk plans a larger version of the Starship/Super heavy combo, with a 12 metre diameter as opposed to the current 9 metres, a more than doubling of the space inside the hull.  This will increase payload to perhaps 450 tonnes, which will cut launch costs per tonne to about $100K to Mars.  My guess would be that the new giant Starship will be in operating in time for the 2027 expedition.

Who will pay for this new city, these new cities?  They will quickly start paying for themselves.  As I discuss here, the first exports will likely be tourism, both recreational and scientific.  And the settlers on Mars will start making their own hardware, because the cost of bringing stuff from Earth will be so high: solar panels, wind turbines, nuclear generators; rovers; dome construction materials; life support systems (water purification, CO2 extraction, N2 extraction); space suits; robots (for mining water and minerals, for exploration); food production.  All these will be much cheaper to make on Mars than to import.  The Mars city/cities will be a ferment of new ideas and new technologies, and some of those will be sellable—ideas/patents cost nothing to send to Earth.  The first expedition of 10 ships (cargo only) , will cost $210 million, ignoring equipment like rovers/solar panels, etc.  The crewed expedition will cost the same.  But after that cost will start to decline, as the Mars learning curve falls.  Larger Starships will take over, local enterprise starts generating income and cutting costs, infrastructure on Mars will allow Starships to be re-used.  Even without that, these sums are well within SpaceX's capacity to pay (Starlink, their high-speed broadband internet system should earn them billions annually), but it is very probable that governments, scientific organisations, millennial cults, and immigrants will be willing to pay the price of a ticket to Mars.

As I said here, the timetable still looks intact.  First cargo mission in 2022, first crewed expedition in 2025, second in 2027.  With each mission, the costs of sending one tonne of cargo or one person to Mars will fall, and as they do, the movements between the worlds will increase exponentially.  Within two decades, the Mars settlements will be paying for themselves.  And there will be thousands of Martians.

Starship full stack

Image from Gravitation Innovation via HumanMars.  SpaceX is prob'ly going to tweak the design again (see the Moon version of Starship), and Musk is muttering about a wider span for the landing legs, but this is what it looks like for now.

Starship assembly line starts

If Musk's claims that Starship will cost just $5 million to build are going to be right, then Starship will have to be built on what is effectively an assembly line.  He's planning to build 2 Starships a week.  And recent images from Teslarati show a nascent assembly line in Boca Chica.

Nose cone construction at Boca Chica

Tank bulkhead construction at Boca Chica

Elon Musk has posted a new glimpse inside SpaceX’s South Texas Starship factory, revealing a nearly-completed rocket nosecone and indicating that the first upgraded Starship prototype’s flight debut is imminent.

SpaceX teams have been working around the clock for a little over a month to build the first full-scale, flightworthy Starship prototype, a process that only began after two ‘test tanks’ were fabricated, assembled, and pressurized until they burst on January 10th and 28th. Built with improved tools and methods, those test results – particularly from the second test tank – allowed SpaceX to empirically confirm that its current infrastructure and techniques are ready to manufacture orbital-class (and even human-rated) Starships right now.

And so work on the first truly flightworthy Starship prototype – known as SN01 (serial number 01) – thus began in earnest around mid-January, perhaps less than a month ago. Over the course of that month, SpaceX’s South Texas team has made spectacular progress. Starship SN01’s business half – comprised of a Raptor engine section, a liquid oxygen tank, a methane tank, and all associated tank domes and plumbing – is likely just a single big stacking and welding event away from being structurally complete.

Without exaggerating, it’s safe to say that SpaceX has effectively gone from a handful of parts worth of Texas rocket production to a multi-vehicle, Starship production line concurrently manufacturing multiple vehicles in about eight weeks. While it would be theoretically easy for critics and a more general audience to see little more than some cheap stainless steel parts in a few hastily-constructed temporary tents, the reality is that SpaceX has already proven – at a minimum – that a steel Starship built with the exact same tools, facilities, and methods will likely be capable of spaceflight.

SpaceX’s January 2020 Starship test tank program proved as much, demonstrating that thin steel tanks built in tents can serve as orbital-class pressure vessels and survive at internal pressures greater as high as 8.5 bar (125 psi) while filled with cryogenic (extremely cold) liquid. Meanwhile, Tesla’s Fremont factory General Assembly line 4 (GA4) – having continuously churned out high-quality Model 3s for more than a year – has proven that sprung structures can make for fast, cheap, and more or less permanent factory solutions. Prospective SpaceX competitor Blue Origin even based its own brand new headquarters – opened in January 2020 – around an odd U-shaped sprung structure.

So the first flight of SN1 is perhaps weeks away.  Initially, SpceX will do 150 m "hops", then it will increase to 1 k "hops", steadily increasing to 20 k flights, where they will test the "skydiver" landing technique on the way back (and we will see whether SN1 can withstand the associated stresses).

From a piece I wrote earlier (slightly amended):

The SpaceX/Mars timetable still looks doable, unless there is a disaster:

H1 2020: Tests to 20+ kms altitude.

End 2020: Full stack (i.e., Super Heavy booster plus Starship) operational.  First orbital flights of the Starship.

Early 2021: First commercial customers (for satellites), launches of Starlink constellation

Late 2022: Uncrewed mission to Mars (Mars is in opposition in December)

2023??: First commercial space station.  Launched on Starship, built by non-SpaceX companies—or maybe even by SpaceX

2023: 'Dear Moon' circumlunar expedition

2024??: Moon Base Alpha

Early 2025: Crewed mission to Mars  (How many ships?  Here's my analysis)

Early 2027: Second expedition to Mars.  Return of at least one Starship.  

2029: Third expedition to Mars.  Martian population reaches 300.  If Starship works, SpaceX will start designing even bigger rockets, capable of carrying more than 100 passengers, so Mars's population in 2029 could be more than 300.  Return of some Starships.

Zubrin talks Starship with Musk

From an interesting YouTube video from What about it?, covering a conversation between Dr Robert Zubrin, president and founder of the Mars society, and Elon Musk, founder of SpaceX, which took place at the recent SpaceX employment fair in Boca Chica.

1.  There are currently 300 employees at SpaceX's Boca Chica operations.  This will be rapidly increased to 3000.
2. The new (again) LA facility will be used to build raptor engines, while Boca Chica will be where the rest of Starship and Super Heavy are assembled.  Musk plans to build 2 Starships a week.
3. Each Starship will cost—wait for it—just $5 million.  (The Super Heavy will be extra.) My earlier guesses were 10-15 times as high.  This is extraordinarily cheap.  It confirms that SpaceX will be running an  assembly line for Starship/Super Heavy.  Musk's earlier estimate of $2 million per launch (i.e., both Starship and Super Heavy) seems very plausible.  9 launches will be enough  to get a Starship to orbit and to refuel it for the trip to Mars, which means (at 100 passengers) a Mars ticket cost of just $180K.  Just a reminder: SLS will cost $1.5 to $2.5 BILLION per launch.  For the same cost, NASA could send 8000 astronauts to Mars.  Just saying.  Meanwhile, the whole fleet of 1000 Starships would cost just $5 billion.  You'll need fewer Super Heavys because they'll be re-usable several times a day, whereas Starships will have a more limited re-use because they'll be en route to Mars, or on the red planet itself, but on the other hand, the Super Heavys will cost at least twice the cost of the Starship itself.  So $10-$15 billion for the whole fleet?
4. The first 5 Starships will stay on Mars, which makes sense as they will be so cheap.  These will be the cargo versions of Starship, but there is no doubt they could be used as temporary habitats while permanent habitats are built.
5. No nuclear reactors (he means, presumably, NASA's KRUSTY kilopower reactors).  Zubrin pointed out that 6 to 10 football fields of panels would be needed to refuel a single Starship, and Musk replied "Fine!  That's what we'll do."   I still think that will require more Starships than SpaceX has been talking about so far, just to carry the solar panels.  But if Starships are so cheap ....  On the other hand, the next settlers may well be happy to have a diversified mix of nuclear, wind and solar, given the reality of planet-wide dust storms lasting months at a time.
6. The first crew ships will carry just 20-50 people, instead of the 100 each ship is capable of carrying.  Most prob'ly because  of the need for cargo space.
7. Musk also dismissed the whole "mini Starship" idea that Zubrin has been promoting.  Starships will be so cheap and production so rapid that leaving a Starship on Mars for 2 years (the Mars-Earth orbits only "sync" every 26 months) will only add a small amount to total costs.   
8. SpaceX will go for a 100 km high launch immediately after the 20 km launch.  Though he didn't say whether this would be SN1 (Serial number 1) or SN2 (both under construction at Boca Chica right now) which will attempt these landmark milestones.  100 kms (suborbital) will allow Starship to do point-to-point flights, and to circumnavigate the globe.  
9. Zubrin thinks that it is very likely that SpaceX will put boots on Mars before NASA gets to the Moon.  Looks very likely, doesn't it?
10. Progress constructing the first two test models of Starship, SN1 and SN2, has been extraordinarily rapid.  Subject to bureaucracy, the first test flights could happen as soon as April.

SpaceX ready to build first real Starship

SpaceX's progress building its new stainless steel Starship is extraordinary.  SpaceX's pivot away from carbon-fibre composites to stainless steel started just over a year ago.  Although SpaceX had lots of experience building carbon-fibre rockets, it had none with stainless steel.  Things have changed a lot since then.  And as usual, SpaceX is moving at incredible speed, and each apparent setback in fact gives them a chance to improve the design or the construction techniques.  In effect, each new rocket is a sort of prototype, tweaked and improved from the previous one.

From Teslarati:

After a busy several days of rocket hardware testing, Elon Musk says that SpaceX may be ready to build the first Starship prototype destined for space.

According to Musk, one test in particular – performed in South Texas just yesterday – is an encouraging sign that SpaceX’s Starship team is becoming increasingly competent at building the massive steel parts that will ultimately make up the generation launch vehicle. For SpaceX, the particular skills and expertise needed to precisely and consistently build a launch vehicle – let alone a rocket as large and complex as Starship – are quite a bit different from those it has mastered with Falcon 9, Falcon Heavy, and Dragon.

A lot of the expertise – particularly engineering talent, countless lessons-learned, and insight into reusability – is directly transferable from Falcon rockets to SpaceX’s Starship/Super Heavy program. Where it really isn’t transferable, however, is in the methods required to actually build the steel subcomponents that must ultimately be assembled together to form the rocket’s upper stage and booster. As a result, SpaceX has spent more than a year focused on building, testing, scrapping, improving, and re-testing any number of critical Starship components. Over the last four weeks (and last few days in particular), that testing has come to a head and Elon Musk believes the results have opened the door for SpaceX to begin building its first space-bound Starship prototypes.

SpaceX’s latest round of full-scale Starship hardware tests began just 10-20 days ago, depending on how one counts. Back around the start of the new calendar year, SpaceX began rapidly integrating two new Starship bulkheads and two cylindrical steel rings (barrel sections), ultimately delivering a finished ‘test tank’ after just 20 days of work. On January 10th, scarcely 24 hours after the two halves of the test tank were welded together, SpaceX sent the Starship test tank to its nearby launch pad and pressurized it with water until it quite literally burst.

Musk tweeted the results of that intentional test-to-destruction just a few hours after it was completed, revealing that SpaceX’s upgraded production and integration techniques enabled the tank to survive pressures almost 20% greater than the minimum Starships will need to perform orbital launches.

“Critically, the tank reached a maximum sustained pressure of 7.1 bar (103 psi), 18% more than the operating pressure (6 bar/87 psi) Musk says Starship prototypes will need to begin orbital test flights. At 7.1 bar, the test tank would have been experiencing an incredible ~20,000 metric tons (45 million lbf) of force spread out over its interior surfaces — equivalent to ~20% of the weight of an entire US Navy aircraft carrier. Perhaps even more impressive, that same Starship test tank was built from almost nothing extremely quickly, going from first weld to said pressurization test in just three weeks (20 days).

With relatively minor improvements to welding conditions and the manufacturing precision of Starship rings and domes, Musk believes that SpaceX can reliably build Starships and Super Heavy boosters to survive pressures greater than 8.5 bar (125 psi), guaranteeing a safety margin of at least 40%. Even a minor improvement of ~6% would give Starship a safety margin of 125%, enough – in the eyes of most engineering standards committees – to reasonably certify Starships for orbital test flights.”

In the last few days, two new bulkheads and steel rings came together to form Starship test tank #2, which was subsequently prepped for transport and moved about a mile down the road to SpaceX’s launch facilities on the morning of January 27th. Scarcely a few hours later, well before anyone was paying close attention for test activities, Elon Musk took to Twitter to reveal that the second tank had already been subjected to a pressure test with water. That second tank reportedly survived up to 7.5 bar, an improvement of about 6% compared to the first tank.

This time, however, the tank wasn’t actually catastrophically destroyed by the pressure test, instead developing a leak around the weld connecting the two halves that lead SpaceX to back off. Musk says that that presumably small leak will now be repaired, after which the same tank will be tested again but with one significant difference. Musk says that Test Tank #2’s second pressure test will be performed with a cryogenic liquid — most likely liquid nitrogen (LN2).

In replies after his reveal, Musk noted that he believed the second test tank could perform significantly better if pressurized with a cryogenic liquid. That’s because certain types of steel – particularly those SpaceX has chosen for Starship – exhibit something known as cryogenic hardening when exposed to extremely cold temperatures, producing steel that can be dramatically stronger by some measures.

Ultimately, as mentioned above, a tank pressure safety margin of 125% is the minimum most engineering standards provide for any given orbital-class launch vehicle. At 7.5 bar, even under the very unlikely assumption that Starship tanks will not see even a marginal strength increase at cryogenic temperatures, SpaceX’s second Starship test tank has officially hit that 125% safety margin. As Musk himself noted on Monday, he is now confident that SpaceX can immediately start building the first Starship destined for spaceflight and further revealed that two of that particular Starship’s three tank domes are already nearing completion.

From a piece I wrote earlier this month (slightly amended):

The SpaceX/Mars timetable still looks doable, unless there is a disaster:

H1 2020: Tests to 20+ kms altitude.

End 2020: Full stack (i.e., Super Heavy booster plus Starship) operational.  First orbital flights of the Starship.

Early 2021: First commercial customers (for satellites), launches of Starlink constellation

Late 2022: Uncrewed mission to Mars (Mars is in opposition in December)

2023??: First commercial space station.  Launched on Starship, built by non-SpaceX companies—or maybe even by SpaceX

2023: 'Dear Moon' circumlunar expedition

2024??: Moon Base Alpha

Early 2025: Crewed mission to Mars  (How many ships?  Here's my analysis)

Early 2027: Second expedition to Mars.  Return of at least one Starship.  

2029: Third expedition to Mars.  Martian population reaches 300.  If Starship works, SpaceX will start designing even bigger rockets, capable of carrying more than 100 passengers, so Mars's population in 2029 could be more than 300.  Return of some Starships.

What will delay the timetable by 2 years will be SpaceX having to ditch stainless steel and go back to carbon-fibre composites.

But Glyn Shotwell, SpaceX's COO, who is less given to "Musk time" than the great man himself, said (in October):

“We want Starship in orbit next year; we want to land it on the moon before 2022 with cargo and with people shortly thereafter,” Shotwell said.

However, much like Musk in his presentation last month, Shotwell hedged her estimate, saying that “every time I make a prediction about schedule I turn myself into a liar.” Most of SpaceX is focused on the company’s Crew Dragon capsule, which is undergoing a final series of tests before it flies two NASA astronauts.

“It’s a critical program for us, as it’s our first step to flying astronauts,” Shotwell said.

Shotwell said SpaceX wants to fly Crew Dragon frequently so the company can learn as much as it can about flying people safely.  

Implication:  they're ahead of the timetable—a Moon landing before 2022 and a crewed landing in 2022.  Will that bring forward the first expeditions to Mars?  Prolly not, because we can only journey to Mars roughly every 2 years.  However .......  If Starship lands easily and repeatedly on the Moon, in 2021 and 2022, proving that it's safe, will SpaceX be tempted to send the first expedition to Mars with a small (10-20) crew in 2022, and not wait for 2024 for the first crewed journey?  Will we see people on Mars in 3 years?  If Starship successfully lands again and again on the Moon, it's not that different in principle to landing on Mars, even though Mars is much further away.  That would be extraordinary.  SpaceX's rapid progress with Starship makes it seem just possible.

Living on Mars -- V

Surprise.  Musk thinks BIG!  Who would have thought?

He's planning that SpaceX will build 100 Starships a year, so that by the end of 10 years there will be a fleet of 1000.  At every 'orbit sync' (i.e., when Mars and Earth are in opposition) a fleet of 1000 ships would set off for Mars over a 30-day period.  They would be prepped for the journey by being refuelled and loaded up first.  He plans to use each Starship 3 times a day—presumably for point-to-point on Earth and for lifting cargoes into LEO (low Earth orbit), since the trip to Mars will take at least 6 months there and back, so that they'll be unavailable to work for shorter trips over and near Earth for at least one quarter of the time.  However, Starships could fly to Mars, unload fast and return after just a couple of weeks on the surface, and when they weren't being used on the Mars run they could be used for the Moon (4 days each way), lifting stuff into LEO to service space stations and space industries, or flying point-to point on Earth.

So plenty of re-usability, just not as much as what you'd get when a Starship is used only for point-to-point suborbital flights.  (Of course, the Super Heavy booster will never go to Mars, so that will be re-usable 100% of the time, and it would make up more than half the total capital cost of the combo.)  I dunno how the finances of that work out, and whether Musk's statement that each launch would cost under $2 million will be correct, because re-usability is key.  If Starship can be re-used like an aircraft, again and again, thousands of times, its per-launch cost will be very low.  On the other hand,  it doesn't have to be used thousands of times to slash costs.   Even if it is re-used just 100 times, the construction and development costs are reduced  by 2 orders of magnitude, because the cost for each ship is spread over 100 launches.  Except for Blue Origin's re-usable space ships (which still haven't yet flown in orbit)  there is nothing comparable out there.  All other launch vehicles are used just once.

Musk had previously talked about a million inhabitants of Mars within 50 to 100 years, but at 1000 ships every 26 months, the target could be reached in 20 years.  Hmm.  He's obviously relying on the Starships paying their way, even on the Mars route, and hopes to create a market by making journeys so cheap that the market is created.  He has previously said that the Starship/Super Heavy combo will cost less than a Falcon 9 to build, i.e., less than $60 million.  So 1000 ships would have a capital cost of $60 billion.  That's an awful lot for a single firm to pay for.  I'm sure Starlink, SpaceX's extraordinary new high-speed, low-latency satellite internet service will be very profitable and will provide the money for this. But SpaceX does after all have other shareholders, who might balk at watching all that money vanish.

The numbers don't add up.  Here, I estimate that the first expedition will need 10 Starships, 2 crewed and 4 just to bring the electricity generators (NASA's Krusty nuclear power plants, wind turbines and solar panels, most of which will be needed to produce fuel for the return journey) and another 4 to bring all the other requirements for life on Mars.  Of these ships, only one will return at the next 'orbit sync' because there won't be enough fuel for the others to return.  Two years later, another 10 ships, with the same crew/cargo ratio will go.  This time, two will be able to return.  Even if a 1,000 ships launch, 80% will be for energy and other cargo.  This is not like letting immigrants loose in America or Australia, where they could build a log cabin, live off the land, and grow food.  Everything will have to be created—soil, food production, safe dwellings, energy production, just to start with.  Without prodigious sums of money, there is no way we'll have 1,000,000 on Mars in 20 years.  Each 'orbit sync', even with 1,000 ships, will only bring 20,000 humans.  And somehow those settlers will have to be funded, found jobs, found shelter etc.

But all this analysis assumes that those who go to Mars would in principle like to return.  Many may not care.  Mars is wilderness.  As soon as the dome, food, etc technology is working acceptably, there is a real likelihood that millennial cults or simply people who want to get away from government intrusion and oversight will want to set up communities on Mars.  There could potentially be tens of thousands of such settlers.  And because they won't be planning on returning, they will not need the huge energy infrastructure required to make methane for the return journey.  The ratio of passengers to freight would be much higher.  They will be mostly self-sufficient, but there will be some trade.  It'll be a while before things like NASA's KRUSTY nuclear power plants will be easily replicated by small Martian communities.

The first Martian export will be tourism.  The second will be technology—techniques will have to be developed on Mars to make things work, and these technologies will be useful on Earth and the Moon and the asteroid belt too.   Millionaires will fly in with the first ships in the biennial convoy and leave with the last.  They'll expect five-star treatment.  So they'll want real fruit and real vegetables.  Somebody will have to grow them.  The construction of the hotels, in Valles Marineris, and on its rim and the rims of craters like Hellas, and on Olympus Mons, will require building material.  So there will be miners and their robots mining for water, iron ore, phosphates, nitrates, etc., and there'll be builders (and their robots) building these hotels and their landing pads and eventually the roads between them.  Millionaires will go for jet-pack flights over Valles Marineris or craters, they'll luxuriate in spas with extraordinary views across wilderness, they'll trek across the Martian surface to see the sights, they'll want cabarets and entertainment, and they'll certainly expect live servitors not robots.  There could be thousands of visitors every 'orbit sync'.  And thousands of employees and small businesses, who will remain on Mars, scraping a living between 'orbit syncs'.

So one day Musk's vision of 1000 ships setting off for Mars will happen.  But eventually, the Martian run will be made with giant spaceliners carrying a 1,000 passengers at a time, which will never land on the surface of either planet, but will be serviced by shuttles descended from Starship from the surfaces of both planets.  Prolly not Battlestar Galactica, but certainly something as spectacular.

The image below shows the liquid oxygen header tank and the nose cone of SN1, the first orbital Starship, being assembled at Boca Chica in Texas.  It really is happening.

SN1 liquid oxygen header tank and nose cone under construction.
Source: Elon Musk

See also:

Living on Mars -- I

Living on Mars -- II

Living on Mars -- III

Living on Mars - IV

Cheap access to space

Starship progress 4x faster than re-usable F9

Elon Musk shares details about SpaceX’s Starship, including estimated 20 to 30-year service life

Elon Musk is still thinking big with SpaceX's Starship Mars-colonizing rocket. Really big.

Cost of the Mars expedition

Starship Mk1 at Boca Chica
Source: TechCrunch, photo by Darrell Etherington

Recently, Elon Musk has said that a single launch of the Starship/Super Heavy combo will cost just $2 million. 

SpaceX’s  goal has long been to achieve truly reusable rocket launch capabilities, and for good reason: The company anticipates huge cost savings through re-usable rocketry versus expendable launch vehicles, which SpaceX CEO Elon Musk  has described as a process akin to an airline throwing away their passenger aircraft every time they complete a flight. They’ve made lots of progress toward that goal, and now frequently re-fly parts of their Falcon 9 rockets and their Dragon cargo capsules — but the Starship spaceship they’re building now should be even more re-usable.

Musk provided an idea of just how much that could save SpaceX — and by extension, its customers — at a surprise guest appearance at the U.S. Air Force’s annual pitch day in LA this week. Speaking with USAF Lieutenant General John Thompson at the event (via Space.com), Musk said that fuel costs for the Starship should be around $900,000 per launch, and that once you factor in operational costs, it’ll probably add up to around $2 million per use. 

[From TechCrunch]

It seems likely that the early Starships will not return from Mars, but will instead be used as temporary habitats while permanent living modules are built on and below the surface of Mars to shelter the first settlers, provide places to grow food, create air, recycle water, and all the other things humans will need on Mars to survive.  So each Starship from the first few expeditions that go to Mars will not be re-usable, or not often enough to cut its cost, though the Super Heavy that launches it will be.  Musk (I think) also hinted that the capital cost of a Starship is less than the cost of an expendable Dragon 9, which is $62 million.  (In a previous piece, I suggested that the cost of each Starship may be as low as $10 million, which is prolly too low.  The stainless steel frame might be just 2% of the cost of a carbon fibre composite rocket, but the engines, life support, fittings, etc, will push this cost up substantially.  But it might nevertheless be way below $60 million.)

So the cost of each Starship going to Mars will be, say,  $60 million for the Starship, plus $2 mill for the ten fuel launches to refill the Starship's fuel tanks in orbit, plus the cost of the fuel for the journey to Mars ($1 mill after rounding), plus the cost of the initial launch.  Less than $100 million.  SpaceX plans six ships to Mars of which four will be cargo and 2 crewed.  $600 million in total.  A single launch of the SLS will be between $1.5 and $2.5 billion per launch.  For an expendable vehicle.  And that won't give us any habitats on Mars, included with the SpaceX option.

$600 million to put boots on Mars.  OK, there will be other costs.  Rovers, power sources (wind turbines/solar panels/NASA's nuclear generators), food for at least 2 years, and of course, there will be a third expedition in 2027.    And although we would all like the first crewed ships to carry 100 people as the first ships did in Red Mars (it seems just right somehow, and, spookily, the arrival of the first Starships on Mars will happen 30 years after the first publication of that seminal work, published in 1992), the number will prolly be much lower, the minimum being set by the needed skillset for starting human life in a new and very hostile environment—engineers, biologists, gardeners, technicians, doctors, electricians, scientists, builders, robot techs, and more I don't know about.  Maybe, after all, we'll end up with the "first hundred", split between two ships.  Or maybe we'll have more ships, because we'll need so much food until the greenhouses and protein vats get going.  Each person eats roughly 1 tonne of food a year, so for 100 people, we'd need 200 tonnes of food, perhaps 300 just to be on the safe side.  That's two Starships for food alone!  Add in the cargoes of power generators, and you get to 4 or 5 Starships just for food and power.  So in all probability, the 2025 expedition will need 7 or 8 ships for cargo alone, as well as the crewed ships.

Despite all the extras costs, we're talking about not much more than $2 billion total for the 2022, 2025 and 2027 expeditions, which works out at $250 million  for each year between now and 2027.   That's just over 1% of NASA's annual budget of  $21.5 billion.   If NASA won't pay, the Air Force might.  And if they don't, I suspect SpaceX will have enough resources to do it itself, if no one else wants to play.  In fact, Musk could pay for it personally.  His net wealth is north of $20 billion.

SpaceX might still fail.  Safely re-entering a vessel as big as the Starship into the Earth's atmosphere will be an enormous technological and engineering achievement.  But remember when rival space companies fell about laughing when SpaceX tried its first retro-propulsive landing and failed?  Now, just 3 years later, it is routine.  Something that no national space agency or private company had ever achieved.  And SpaceX achieved it.  Somehow, I am very confident that in 2022, the first uncrewed Starships will land on Mars, followed by the first astronauts 26 months later.  I have to live just another 6 years to see humans on Mars.  I might just do it.

Musk's 2019 Starship presentation

At Boca Chica Texas, right next to the silvery finished (almost—that'll take another month) Starship Mark 1, lit by searchlights, Musk shared his ideas about the future with us as well as providing us with new renderings of Starship.

The new look stainless steel Starship.  Big fins at the back are (mostly) not for lift but to slow down the descent,
like a skydiver.  The aim will be to slow re-entry enough to reduce heat, so some small lift in the upper atmosphere.
Small nubs are landing leg housings.
Steel costs 2% of carbon fibre composite, is much better at cryogenic temps and also at high temps.
Is also re-usable in an emergency and can be re-welded on Mars/the Moon if needed.
The reason they're being built outdoors is that putting up buildings would have taken too long.

The three sea-level engines (with the smaller bows) are in the centre.  They can
gimbel by up to 15%.  The outer three are for deep space travel, and don't gimbel. 
Musk said in a tweet that there were 6 landing legs. 
Presumably the two not shown are buried in the fins right next to the body.

Starship entering Mars's atmosphere.
Heat shield made of small ceramic tiles (material looking like spaghetti under the microscope???)

Use of steel which has melting point of 1500 degrees C permits thinner and lighter
heat shield.  Carbon fibre composite and aluminium melt at 400 degrees.

Super heavy also of stainless steel.  Little fins at the base serve little aerodynamic purpose.
They're housings for the landing legs.

Height of Starship 50 m, of Super Heavy 68 m.

Super Heavy returning to launch pad.
Musk says aim is to re-use both Starship and Super Heavy within 6 hours of landing.

Starship at Moon Base Alpha.
Musk thinks settlement on the Moon will be unlikely,
but permanent scientific bases as with Antarctica will exist.

Not just our moon, but also the moons of Jupiter and Saturn.

But colonisation of Mars remains primary goal.  We may be the only places with sentience in our galaxy.
There's no evidence of alien civilisations (The Fermi paradox). And it took 4.5 billion years for sentience to emerge here.
If it had taken just 10% longer, it would have been incinerated as the sun heated up over the next
500 million years.  Implication:  we have duty to spread life and sentience through the universe.
 

I'm doing this from memory, as the livestream video won't play, now that the presentation is over.  No doubt, SpaceX will upload the video in the next few days.  His timetable is as usual tight:

• Starship Mk1 flying to 20 km (65 K feet) within a month or two
• Starship Mk 3 and 4 built within 6 months.  These will be full sized.  Can't reach orbit by themselves, so Super Heavy must be built first.  Expects that to happen within 6 months, so first orbital tests next year.
• Is only devoting less than 5% of SpaceX's resources to Starship.  However, cost of testing and iterative development much more expensive than building the prototypes.  Still focused on getting Crew Dragon working ASAP.  
• Expects that they will build at least 10 Starships.  Total annual launch capacity (because they'll be rapidly re-usable) will be 50 times larger than total existing launch capacity, including SpaceX's existing fleet.  (I see capacity is back up to 150 tonnes from 100 in the previous version)  Unstated implication is that launches with Starship/Super Heavy will be super cheap, else where will demand come from? 
• Will use both Boca Chica and Florida for launches.  Was cagey about what Boca Chica would look like in 10 years, but it's obvious: a massive spaceport.
• Because both Super Heavy and Starship will be rapidly re-usable, testing will be able to proceed much more rapidly and much more rigorously.  With expendable rockets you'll need 10 rockets to test the design 10 times.  With Starship, you'll only need one.
• Will test uncrewed first.  So first Mars and Moon missions will be automated and uncrewed.
• The biggest difficulty he sees in the design and construction of the spaceships.  Life support, for example, he sees as a much easier.
• Will ultimately make methane on Earth as well as Mars using the Sabatier method.  Needs 3.5 tonnes of oxygen for each tonne of methane and will extract the oxygen near the spaceport, rather than shipping the huge volumes needed in.
• Rapid technological and manufacturing progress.  For example, will no longer cut the steel into squares, but will just unroll it from the rolled steel coil and shape it to the circumference of Starship with a single cut and weld.  Hence even more rapid timetable than we have seen to date. Will have to step up pace of Raptor engine manufacture from one every 8 to 10 days to one a day by or before Q2 next year.

My conclusions?  SpaceX is very much on track to achieve its timetable.