SpaceX Starship Can Reach Mars in Just 45 Days

28 thoughts on “SpaceX Starship Can Reach Mars in Just 45 Days”

1. Don’t forget the Mars Cycler concept…a ship that does a continuous Earth Mars elliptical transit primarily using gravity…then ferrying to and from both planetary surfaces to move people and cargo. Slower but cheaper and less fuel demanding…can supplement the faster ships.

2. What would Gerard O’Neill do to get to Mars?
   I bet it would not be what Musk is planning.
   A million Starship flights with this, that, and another.
   That guy just uses to much hyperbole, exaggeration and embellishment for my taste.
   He’s a freaking Wizard of Oz. and in some ways a snake oil salesman on pot and LSD.
   I bet O’Neill would use mass drivers to deliver smaller but more frequent payloads to Mars.
   Setup a solar powered linear accelerator in space and pew pew pew those supplies to Mars in 10-14 days.

   • Oh please … at least TRY to do a calculation or two to back your propositions!

        V = at … velocity is acceleration times time (seconds)
        D = ½at² … and for a bunch of [a], it’ll go D meters in the same time down track

     So, we need ΔV of about 16 km/s or 16,000 m/s. To keep D shortest, use highest acceleration reasonably tolerable. If ‘people’ then 3 Gs or 30 m/s². If cryogenic tin cans of fuels and oxidizer, then (maybe) 5 Gs. Otherwise the thickness of the cans gets too much and we’re just pew-pew-pewing can mass.

        16,000 = 30 t
        t = 530 seconds

        D = ½at² = ½ × 30 × 530²
        D = 4,270,000 m or 4,270 KILOmeters.

     That’s one long, long track. Even if ‘bent into a suitably large circle’, then the centripetal force to make the curve — again limited by 3 G = 30 m/s² from the formula is:

        F = V² / R (radius)
        30 = 16,000² / R
        R = 256,000,000 ÷ 30
        R = 8,500 km.

     Nope, that didn’t fix our acceleration forces problem. Might as well just be a straight track. Zipping away for almost 9 minutes at 3 Gs. Travelling over 4,200 km down the track. Better be a wickedly straight track!

     And that in turn brings up the next problem. If ‘the track’ is viewed (in the mind’s eye) as a long, think piece of dry spaghetti noodle, given 2.5 mm spaghetti, and I’m assuming maybe what, 25 meters or so ‘wide’ for the mass thrower? then spaghetti is is 10,000× narrower, so 4,200,000 m ÷ 10,000 = 420 m. Imagine a piece of spaghetti 420 meters long! Over 4 football pitches.

     Hanging in space.

     What would you want to figure would be its bending, subject to being pushed in the opposite direction of the tin can racing down the track by the counter electromagnetic force? It’ll wiggle like crazy! One could of course build a much, MUCH wider truss contraption to stiffen the track a bunch.

     But it still would need to be more or less 3% to 5% of the length, in width. 3% of 4,200 km is 126 km. Just saying … that is a HYOOJ structure to build, to chuck various tin cans toward Mars.

     ⋅-⋅-⋅ Just saying, ⋅-⋅-⋅
     ⋅-=≡ GoatGuy ✓ ≡=-⋅

3. Purely a guess, but it would be unthinkable if Musk did not turn his sight to nuclear propulsion once the BFR fleet is done. It is a rational and only upgrade, with impossible political an regulatory obstacles. That is where Lunar base comes in. There are no politicians or regulations there, and NTP motors can be tested in vacuum without little green people protesting against everything. Also, out there it would be possible to collaborate on it with those interested parties that already have such tech, because politics would be 384kkm below, and clear path to Mars. But same as Musk makes his own battery cells, he will want to do his own NTP motors and fuel in situ. No mining permits on Luna, and free vacuum opens technological possibilities impossible on Terra. He would save 10~20 years though by simply buying all that for the whole fleet for the rest of his life. But BFR fleet is a foot in the door only, NTP is the definitive solution for the Mars project. That is what NTP was meant to be back in the day.

4. For All Mankind is pretty decent tv series. It shows what would happen if space race never ended.
   https://www.imdb.com/title/tt7772588/

5. Anyone can do Tsiolkovsky’s rocket equations … practically on a napkin, and confirm numbers like cited both by commenters and the original author’s article. You need very few parameters to get an idea of duration and speed.

   ISP = 380 for methane-oxygen “MethaLOX” SpaceX engine (Google)
   M₀ = 620 tons (600 fuel, 20 shell-and-payload)
   M₁ = 20 tons, right?

   Tsiolkovsy’s:

   ΔV = ISP G₀ ln( M₀ / M₁ )
   ΔV = 380 ⋅ 9.81 ⋅ ln( 620 ÷ 20 )
   ΔV = 12,800 m/s

   See? Easy-peasy. And what does 12.8 km/s do for a rocket anyway in terms of time? Well … one has to know how far said rocket is going to have to go. Mars optimally is 1.38 AU (perihelion), but doesn’t correspond well with Earth’s aphelion (furthest out from Sol). So, figure the conservatıve 1.5 AU. And for Terra, 1.0 AU. After all its just cocktail napkin math.

   ΔAU = (1.5 – 1.0) = 0.5 …× 150×10⁹ m/AU = 75×10⁹ m

   In a co-rotating frame. Basically a nearly straight line. Lots of meters.

   t = distance/velocity = 75×10⁹ ÷ 12,800 = 5,860,000 sec = 68 days

   OK, not quite 45 days (but as Brett says in a nutshell, “who cares”), but on the same order. If you are becoming dâhmned tired of your cramped quarters in a week of 7 days, and going crazy by 45, an extra 20 isn’t going to lead to a mutiny. More provisions all around!

   I’m sure it was included somewhere, but not said, that to climb from Earth to Mars against Sol’s gravitational field also takes ΔV down a notch. Not exactly sure of the math, but either 1.5 km/s or 3 km/s. Orbital dynamics are far beyond napkin math.

   That adds to the time. Start off near Terra at 12.8 km/s, and end up near mars at ‘only’ about 10 km/s. Our 68 day simple trip becomes (grind, grind, smoke, curses) about 82 days. Precariously close to the 90 day transit.
   ________________________________________

   While it has been said in this article that the trip can be trimmed to 45 days using ‘wasteful’ chemical means (and it can, apparently), it must also be said that Brett’s money quote “who wouldn’t rather get to Mars with plenty of supplies” (or something akin to that) is prescient. Sure, lots of big ol’ tin cans full of cryo-fuels can be shipped in tandem to Mars from Earth well before needing them (or who knows, because of boil-off, maybe “just in time”?), allowing all sorts of maneuvering to be done. Like getting down to the surface, shedding the ΔV of getting to Mars itself, all that. Aerobraking, Smaerobraking. With plenty of cheap fuel, just retro-grade rocketry to a halt.
   ________________________________________

   However, in writing up this response, I was struck by one big nugget. Basically, that it is insanely stupid to be sending a bipropellant up to orbit, and off toward Mars, to try to capture it at the end and then use it … compared to sending the same MASS up there, and not even necessarily cryogenics (tho’ Argon has advantages), and use it as reaction mass for a nuclear FISSION powered rocket engine of far higher ISP, allowing much lower burn-down, with plenty of reserves for both the landing phase, and in case we forgot … the RETURN FLIGHT. Oh hêll yah. That part.

   Fusion is a great idea, much too talked about (in my humble opinion), compared to using our nuclear bearskins and stone knives approach with high enrichment, high intensity fission. We’re not talking reactors with replaceable core parts and fuel rods. Welded together, a hundred missions, or while the fission business is possible. Reload with reaction mass (exactly as envisioned for the Musk-a-GoGo rocket) every time its on the refueling elliptic orbital highway.

   With conservative ISPs of 1000 to 3000, using ions and electric fields, 50% of the fully loaded mass could transit Earth to Mars in under 40 days. (Isp of 2000). That is a LOT of payload, assuming that maybe ⅔ of the delivered-to-Mars mass is payload. ⅓ of the Now-Leaving-Earth mass. 200 tons out of 600. A lot of soylent green in those food tubes. And all the reaction mass (and food!) to get back after a few months of toodling around on Mars’ surface.

   ⋅-⋅-⋅ Just saying, ⋅-⋅-⋅
   ⋅-=≡ GoatGuy ✓ ≡=-⋅

   • With nuclear, the game changer isn’t getting there faster, though that’s nice. Just “nice”, but nice.

     The game changer is not having to launch at synodic periods. Which between Earth and Mars are about every 780 days. The extra delta V nuclear permits lets you launch whenever you want.

     So, instead of a 90 day transit every couple of years, you’re doing it twice a year. With six of those beasts, you launch once a month, land at Mars once a month.

     That’s a lot more important than the 90 days, the fact that you’re not having to wait a couple years between missions.

     Note that the extra delta V from nuclear does NOT have to be high acceleration delta V. A measly 0.02m/s^2 would be fine. 0.1m/s^ would be fantastic.

     The nice thing about chemical rocketry isn’t the ISP, which is pathetic next to nuclear. It’s the thrust to weight ratio. Which on Earth has to be higher than 1 or else you’re not going anywhere.

     So, chemical rocketry from Earth’s surface to LEO is unavoidable until we either us non-rocketry, or hang nuclear regulators from the nearest lamp post. Even in the latter case, it’s tough getting a decent thrust to weight ratio pushing hydrogen through a fission reactor, though; Nerva engines had a thrust to weight ratio of 5, without any tankage or payload. Maybe you could have launched from Earth’s surface using the nuclear lighbulb engine.

     But for going between planets? Yeah, nuclear it the obvious way to do that, given that you’ve hung the regulators.

   • With fission as the means, water becomes the universal medium of exchange, storage & supply of fuel, air for breathing & how you wet your whistle. Unlimited power changes everything wrt the design of a spacecraft, just as it does for ships. Mostly for the better.

     • What you say is true: H₂O, water … becomes VERY attractive as the universal ‘stuff to move around’. It conveniently isn’t a really low boiling point cryogen, it can be broken apart for it H₂ and O₂ constituents, useful in their own right, and … if we think ‘how about as ions’, for direct electrical propulsion, it might be good at that too.

       Except it is not.

       Hydrogen, as a propulsion-by-ionization-and-acceleration medium offers wickedly high ISP numbers for modest acceleration voltages. Crazy attractive. With the small drawback that it is the worst possible species for imparting momentum into one’s spacecraft going the opposite way. At the opposite end — Xenon — has such a high per-ion mass (and nearly perfect non-reactiveness) that it was chosen for super-deep space missions as the ion gas. The downside is that it is RARE stuff. Millions of liters of air needs to be liquified, then distilled to conserve it as a trace gas … to produce a measly liter or two.

       By comparison, argon Ar is an almost perfect compromise. Middling heavy (40 AMUs) between H (1 AMU) and Xe (131 AMU), but completely abundant. 1% of the atmosphere. A copious byproduct of the liquid-air industry, so cheap to make that it is a common steel/iron welding gas.

       So, I think it is argon.

       One COULD make an argument for SF₆, (146 AMU) sulfur hexafluoride, a totally non-toxic, almost completely non-reactive molecular gas. Kind of a cryogen (–50.8°C boiling point). Stable for eons. Given how much fluorine we produce, and ridiculous amounts of sulfur, this might be a good candidate. Dunno.

       ⋅-⋅-⋅ Just saying, ⋅-⋅-⋅
       ⋅-=≡ GoatGuy ✓ ≡=-⋅

6. I do not want to dismiss falcon rockets, they demonstrated that they can work and work well. My criticism is about: 1) tesla fsd claims while just few months ago they had to do the software recall for millions of vehicles introducing new warnings, because it is not fsd and would be a safety risk claiming otherwise (and false advertising). 2) The celebration of starship blowing up while there is constant downplay of other programs that delivered much more (for example artemis). 3) the assumption that diffused use of robotic automation is defacto equivalent to the success of teslabots, while Boston dynamics has already products on the market. 4) all the sub par performance of the boring company/tesla solar/twitter(!) depicted as disruptive successes.

   • “2) The celebration of starship blowing up while there is constant downplay of other programs that delivered much more (for example artemis).”

     My God the delusion. Artemis has delivered nothing. If Starship had a payload then it would have made LEO. We are on the cusp of fully reusable super-heavy boosters that can put 100 metric tons in to LEO (and have a pathway to up to 200 metric tons) and you are crying about Artemis not getting praise.

     • So sending a capsule in orbit around the moon following exactly the mission abjectives is NOT a success while exploding starship twice is a success? Ok.

       • After this amount of time (basically since GW Bush reign) and this amount of money a single use rocket launch and unmanned flight to the Moon is understandably less appealing than even a Starship RUD: a RUD still gives some hope for something meaningful (new) in the near future. And why NASA doesn’t even try to design its own lander? And when is the next Orion flight really due? Besides, if SX makes it to orbit and then land it, what will even be the point in Orion, and its launcher?

     • Test launch explodes while doing something dead simple and the official cope is “It’s fine, next time we probably won’t explode in that specific way?” Suppose this issue went undiscovered until a crewed mission? Unbelievable disrespect for engineered safety. Musk and fans could show even a little concern for the glaringly foreseeable and avoidable accident, rather than immediately trying to save face.

       A crewed space program is a deadly serious commitment with no place for hubris or ego. We owe our astronauts nothing less than engineering perfection. Every time you send them up, you might watch them die. And excuses won’t bring them back.

   • Every failure with starship so far was basically expected. Go read up on early Apollo! They overstress the system on purpose to judge exactly what it can take.

     • Apollo never lost… anything, once it left the ground. Like, ever. Shockingly successful program. We could all really learn a lesson from Apollo. Like the usefulness of rockets that don’t explode.

7. This is dumb. If you do want a rapid 45day transit, separate cargo and crew. Stage cargo in orbit around Mars for RDV and landing. For crew don’t use Starship but inflatable+ interplanetary stage. For interplanetary crew flights, this reduces tanker flights to <4, accounting for boil off margin of 25% (which is too much as cryocooling in LEO has become simple affair). All this is done in LEO.

   Crew vehicle is ~20T burnout mass with ~600Ton Methalox. You get 12KM/s delta-V
   Or
   Crew vehicle is ~20T burnout mass with ~600Ton Hydrolox. You get 15KM/s delta-V

   A 10 ton inflatable is quite large for a 6 person crew for <2months.

   Earlier you sent Starships on slow efficient 9 month trajectories to Mars.

   For descent to Mars, board one of the Starships in orbit around Mars.

   • You’re just not doing 45 day transits, period. This is a colonization effort, not a race. Any technology that can get you to Mars in 45 days can get you there in 9 months with enormously more payload. Enough payload that the payload is your radiation shielding!

     What colonist is going to prioritize a short trip over plentiful supplies?

     OK, if we had some major SF technology, such as fusion rockets with high thrust to weight, maybe the time savings would be worth it, though the cargo would still take the lowest energy route.

     Now, with aerobraking, you can get to Mars in roughly half the time, since the aerobraking saves a lot of delta V. So you might see cargo taking the 9 month Holman transfer ellipse route, and the people taking a 4-5 month passage in ships with lower mass ratio, but still feasible for chemical rocketry.

     But I’m betting that even then, many of the colonists would prefer taking the slow trajectory and arriving with twice as much cargo.

     • Let’s agree to disagree, even in a colonization effort. On 45 day trips radiation shielding by soft goods and water/food bags on an inflatable is ample. With Starship (lifeboats) staged in Mars orbit, awaiting crew, there is no need to stretch crew boredom in interplanetary stint out to 6 or 9 months.

       Besides, what I propose is only relevant to first decade. You probably know this, but the Philip Lubin crew is starting to build hardware with land based and in space tests of laser propulsion demonstrators supposedly in the pipeline for this decade (DEEP-IN, Directed Energy Propulsion for Interstellar Exploration).

       As it comes online -and if Musk succeeds in Landing on Mars investors for the laser propulsion will be found easily- no chemical prop will be needed. All crew will become a ping pong ball in an interplanetary laser bank infrastructure. You’ll do the trip in a small 3-5 metric ton capsules reaching Mars in 3 days and slowed down by counterpart laser bank in 3 additional days. All this at below 1G acceleration. Within the solar system interplanetary-laser-station commutes beat fusion propulsion unless you absolutely need flexibility.

       Starships will be very useful for reusable landing and liftoff at Mars, and forming part of the MARS orbital infrastructure, but not for the crewed interplanetary legs.

     • “What colonist is going to prioritize a short trip over plentiful supplies?”

       No colonist. Going fast and light will be military.

     • That’s a great argument if you’re only sending one rocket. If you’re sending lots of rockets, you can send slow cargo and then fast people.

8. I said it before and still think this will be the case:

   Starship project is progressing, but very slowly, many years will pass until it will take humans to Mars.

   We will have AGI, maybe even ASI before reliable, advanced ship, which is able to transport people to Mars.

9. Ok, it’s possible, but no sane person would do it, because it requires about 6-12 times the resources necessary to do it more efficiently on a shorter timescale. It would be a stunt, nothing more.

10. The level of hype around everything Musk does is absurd. Until starship does not demonstrate that they can complete one orbit before blowing up they cannot even start troubleshoot in orbit refuelling, and then they will need dozen of refuelling trips in a very short time (you need to remember that the that the system is planned for supercooled cryogenic fuel) for a mars mission. Furthermore even with everything going right you forget to mention that the 45 days trip journey is possible only when earth and mars are in the correct orbital positions (which happens approximately every two years)

    • Agreed. They are a long way from proving safe for even one orbit, let alone safe for crewed missions. At the present rate of testing, it’ll be 2-6 years before the latter is proven, with the 6 year worst case if there are repeated blowups.
      Also, instead of refueling a finite tank with tankers that themselves need refueling to get to Mars alongside – or ahead of in a less fuel-burning more elliptical pace – it would make more sense to devise a way to attach extra boosters to Starship in LEO, where most of the mass penalty has already been paid getting to LEO. This is reminiscent of how Star Trek built its (true) starships off-planet. It makes far more sense than a series of refueling ships that need more refueling ships and ultimately Mars refueling ships too.
      Some pre-landing fuel creation facility should be established on Mars with robots before any humans are sent to this dangerous destination. Actually, it would make much more sense and be immensely safer to establish a lunar colony first, with just a 3-4 day trip, anytime, instead of a 45-90 day trip only once every 2 years.
      The problem is Musk: he wants to retire on Mars, and he’s running out of time. He’ll be 60 in 8 years – which just happens to be when he recently announced he expects the first crewed landing on Mars by SpaceX. His need to be first should not dictate planetary priorities.

    • Actually, the text mentions the specific date of 2033 for this 45 days to Mars trip. So it’s a very specific alignment that allows that.

      As for the Musk hype, while true, bear in mind that SpaceX launched over 100 times in 2023. 2/3 were Starlink launches, but the other 1/3 was STILL more than the rest of the world combined, excluding China. And about 4/5 of those Falcon launches were REUSED first stages. Just 5 years ago, your kind was saying “landing rockets is probably impossible, if possible, it won´t be profitable, if profitable, it won´t be safe and probably can´t reuse more than a couple times”.

      Starship is completely revolutionary, so a difficult path was expected. However, the only reason the last launch didn´t make to orbit was the venting of oxygen… extra liquid oxygen that was there because of a lack of payload.

      Were you also this pessimistic when Falcon failed to land several times?

      • Indeed, we’ve gotten pretty blase about Falcon, it’s easy to forget that their first successful launch was in 2010, and they were successfully landing them 5 years later.

        And that was a company that was starved for resources compared to today’s SpaceX.

        They will most likely make orbit with the next test flight, and if I had to bet, will be, (Barring regulatory interference!) successfully landing at least the booster this year.

        And that’s enough, even treating the 2nd stage as expendable, for Starship to be more economical than Falcon. So their test program for landing the 2nd stage will actually be producing revenue.

        • And remember that the first three Falcon 1 rockets failed.

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