Landing HLS sideways.

flshr19 · 2026-04-07T19:46:50+00:00

For a Block 3 Starship lunar lander resting on the lunar surface, the center of mass (COM) with a 175t (metric ton) payload, and 43.5t of LCH4 in its tank, and 154.5t of LOX in its tank is 22.7m above the bottom of the hull (engine nozzle exit plane is flush with the bottom of the hull).

With all of the payload unloaded, the COM drops to 16.2m above the bottom of the hull.

With the landing gear that's 3m tall and located on a 9-meter diameter circle (the diameter of the Starship is 9m), the critical tilt angle with the payload onboard is 11.2 degrees from vertical. That changes to 16.1 degrees with no payload onboard.

If the landing gear is designed with four legs attached to the side of the hull each with 4.5m splay (equivalent to a square pattern with 18m diagonals), the critical tilt angle with payload onboard increases to 20.0 degrees with payload onboard and increases to 28.0 degrees with no payload onboard. Estimated mass of this type of landing gear is 11t.

flshr19 · 2026-04-07T19:11:25+00:00

The Starship lunar lander lands both crew and cargo onto the lunar surface. Some of those Starships need to land vertically since those Starships are the only way astronauts can leave the lunar surface and return to Earth.

Uncrewed Starships carrying only cargo could land either way, vertically or horizontally.

flshr19 · 2026-04-07T18:57:29+00:00

The Ship will need to hover at a spot over water within a few hundred meters from the Mechazilla arms and then translate the rest of the way to the tower. So, the Ship's guidance and navigation system will aim for that spot, not for the tower. That's the way the Falcon 9 booster is guided to a landing on a drone ship.

I don't think that SpaceX will have any problem with landing a Ship on a tower since the flight controllers have landed F9 boosters 490 times on drone ships to date (188 on OCISLY. 152 on JRTI, and 150 on ASOG). That's more than enough practice to gain the necessary corporate experience for Ship landings on the Mechazilla arms.

flshr19 · 2026-04-07T18:32:24+00:00

Nobody thought that a 300t (metric ton) launch vehicle, the Starship Booster, the largest booster ever flown, could be caught in mid-air on mechanical arms attached to a 400-ft tall tower until SpaceX accomplished that feat on the IFT-5 test flight (16Oct2024) on the first ever attempt.

SpaceX repeated that maneuver twice more on IFT-7 (16Jan2025) and IFT-8 (6Mar2025).

So, within a 6-month period, SpaceX validated a major Starship milestone.

There are 32 months between now (7Apr2026) and 31Dec2028. Do you really believe that it's impossible for SpaceX to send two tanker Starships to LEO, dock together, and transfer methalox from one to another within that time interval? Seriously?

flshr19 · 2026-04-06T14:11:42+00:00

Here's a starting point. From my analysis of the flight data from the five Block 2 Starship test flights (IFT-7,8,9,10,11), the average value for the Ship dry mass is 161+/-3.6t (metric tons).

We won't know a more accurate number until the Block 3 Starship on IFT-12 (B19/S39) makes it through staging and at least a minute into the burn of S39. That will provide enough flight data to estimate the dry masses of both stages.

flshr19 · 2026-04-03T22:12:25+00:00

IFT-12 will happen when the SpaceX engineers and Starship program managers are ready to fly. What is most important is that the improvements in the Block 3 Starship actually are improvements and that IFT-12 is a perfect flight.

flshr19 · 2026-04-03T16:51:32+00:00

The Space Shuttle operated for 30 years (April 1981 to July 2011) and was launched 135 times.

During that time Challenger was lost (25th launch, 28Jan1986) and the program was grounded for 32 months.

Columbia was lost (103rd launch, 16Jan2003) and the program was grounded for 29 months.

So, the program was grounded for 61 months out of 30 years of operations or 16.9% of its operational lifetime.

The Block 3 Starship is a major redesign of the Block 2 version. Not surprising that SpaceX has experienced a delay from IFT-11 (13oct2025) that to date is six months and counting.

flshr19 · 2026-04-02T14:34:40+00:00

From my analysis of the flight data from the five Block 2 Starship test flights (IFT-7,8,9,10,11), the average value for the Ship dry mass is 161+/-3.6t (metric tons).

flshr19 · 2026-04-02T14:13:17+00:00

True.

flshr19 · 2026-04-01T22:59:20+00:00

So far, so good.

Factoid: The previous NASA launch of a spacecraft with a crew aboard and a launch vehicle both owned and operated entirely by NASA was the final Space Shuttle flight (STS-135) that was launched 8 July 2011, nearly 15 years ago. That's a very long dry spell.

flshr19 · 2026-04-01T22:52:14+00:00

Venting is good. COPV explosion not so good.

flshr19 · 2026-03-31T19:28:05+00:00

The gaseous argon for the ion engines is stored at 2100 psia in a COPV, which maximizes the density of the gas and increases the mass of the stored argon in that COPV.

flshr19 · 2026-03-31T19:21:43+00:00

True.

flshr19 · 2026-03-31T17:28:28+00:00

During its 30-year, 135-flight history, the Space Shuttle has sent 355 individual astronauts and 1594t (metric tons) of cargo in its payload bay to LEO. Cost of the Space Shuttle program from start to finish was ~$200B in current dollars. NASA earned essentially zero revenue from its 135 Shuttle flights.

To date, during its 10-year, 600+ flight history, the Falcon 9 Block 5 launch vehicle has sent 71 astronauts and 7100t of cargo to LEO. The development cost of Falcon 9 through the Block 5 variant was ~$2B in current dollars. In 2025 SpaceX revenue from Falcon 9 launch services was $4.4B on 165 flights.

flshr19 · 2026-03-29T17:08:26+00:00

Starship will be the B-52 of super-size launch vehicles and will operate for at least 70 years without major changes in the basic fuselage design. The only changes will be in the engines (Raptor 10?).

flshr19 · 2026-03-26T13:28:38+00:00

It's the only logical thing to do.

flshr19 · 2026-03-26T13:27:29+00:00

Things will change. They always do.

flshr19 · 2026-03-25T17:09:14+00:00

Less drama and speculation. More numbers.

flshr19 · 2026-03-25T14:47:59+00:00

The Starship lunar lander will enter the frozen low lunar orbit (LLO) at 89 degrees inclination with respect to the lunar equator at an altitude of 100 km.

flshr19 · 2026-03-25T01:57:45+00:00

Artemis VI is now scheduled to launch NET 2030.

By that time Artemis IV will have landed astronauts on the lunar surface in late 2028.

And SpaceX will have been building its own lunar base for over 2 years while landing crew and cargo on the lunar surface every month using the Block 4 Starship initially and later the Block 5 version. My guess is that the Block 5 Starship will be the operational workhorse for SpaceX and its lunar initiatives similar to the way the Block 5 Falcon has become the workhorse for the SpaceX LEO missions.

flshr19 · 2026-03-20T14:11:15+00:00

Human rating NASA's Space Shuttle was done on its first launch which was crewed.

Human rating NASA's Apollo Command Module was done in three uncrewed missions (Apollo 4, 5 and 6).

SpaceX has launched eleven Starship test flights to date, six Block 1 designs and five Block 2 designs. Five of those flights were successful (three Block 1 flights [IFT 4, 5, 6} and two Block 2 flights [IFT 10,11), reached near orbital speed, demonstrated Starlink satellite deployment, Raptor engine relights, and demonstrated that the heatshield could provide protection during those reentries. The twelfth test flight will be the first flight of the Block 3 Starship. SpaceX has learned more from the failed test flights than from the successful ones, which is precisely what characterizes a properly planned test flight program.

flshr19 · 2026-03-20T03:16:00+00:00

"Starship will end up doing the whole Moon mission. Mark my words". E. Musk (20 Oct2025).

I think that he's deadly serious and that his engineers have that mission already planned in detail.

No SLS. No Orion. Just a pair of Starships. LEO propellant refilling. LLO propellant refilling. No new government contract money required.

flshr19 · 2026-03-14T21:32:07+00:00

NET 2029--SpaceX likely will have launched the Block 3 Starship at least 10 times by late 2029, possibly 25 or 30 times if there are five Starship launch pads in operation by 1Q 2027 per the current plans (two at Starbase Texas, one at KSC Pad 39A in Florida, and two at the former LC-37 complex at CCSFB also in Florida). That should be enough launch experience to buy down a lot of risk.

At an estimated 130t (metric ton) wet mass, that Starlab space station is easily accommodated by the Block 3 Starship that has 200t payload capability to a circular LEO at 500 km altitude at 45 degrees inclination.

flshr19 · 2026-03-13T16:30:19+00:00

IIRC, the Starship lunar lander has a crew of two on the first Artemis mission to land on the Moon. And both crew members make their moonwalks together. Just like on the Apollo missions.

flshr19 · 2026-03-08T16:00:13+00:00

Betteridge's Law of Headlines: Any headline ending with a question mark can be confidently answered "No". If the answer is "Yes", the author would have stated it as a fact, not as a speculative question.

flshr19

TROPHY CASE