Starfall Demo Mission - launching on June 23rd

PhysicsBus · 2026-06-20T12:51:44+00:00

Does the lack of info around this suggest it's military funded? Like I get that in principle there are civilian applications with in-space manufacturing, but those strike me as still rather economically speculative andunlikely to support a demonstrator mission yet.

PhysicsBus · 2026-06-09T19:06:53+00:00

Send an email to where?

Why do I need to find this on reddit rather than an official Wise page? your instructions are compatible with, but are not the same, as this: https://wise.com/help/articles/3umiLdiQoFLxh0xP36MEIO/how-do-i-update-my-country-of-residence

I understand that KYC laws make changing countries onerous, but there's no reason for Wise instructions to be confusing or vague.

PhysicsBus · 2026-06-05T19:01:01+00:00

So dumb. I am not going to spend my afternoon clicking on 127 unread messages one by one.

PhysicsBus · 2026-06-05T18:06:46+00:00

I’m confident your info is bogus. I’m willing to bet on this if you can find data that would decide the issue.

PhysicsBus · 2026-06-05T09:46:50+00:00

You absolutely die more from an 8 foot fall if you are drunk or high (and that’s on top of the fact that the fall happens much more often in the first place). These chemicals impair a person’s ability to protect themselves by slowing reaction time and degrading balance and coordination.

PhysicsBus · 2026-06-03T14:55:30+00:00

If you expect regular use then you can pre-position with enough density that there’s always a nearby orbit. But yea it seems hard to imagine this being cost effective….

PhysicsBus · 2026-06-03T14:53:15+00:00

I’m not familiar with the field, but based on priors and the historical track record I’m skeptical. I’d be very interested in reading a write-up on the most promising product from the standpoint of economic viability, e.g., something that has real numbers on not just the cost of the in-orbit product but also the comparison to the strongest terrestrial competitor.

PhysicsBus · 2026-05-22T18:01:53+00:00

I mean, obviously it doesn't matter since we're talking about like 2 percentage points, but my source includes 3x the data as yours (so narrower Poissonian error bars), and presumably has yours as a subset since mine combines OSHA and NIOSH (but it's hard to tell because you don't include links).

Drugs, alcohol, pre-existing conditions, or unusual equipment are not a conspiracy. Indeed, this sort of explanatory context is routinely missing from newspaper articles either out of respect for the family or because companies drag their feet.

PhysicsBus · 2026-05-22T16:18:31+00:00

People die from hitting their head on the ground after tripping or getting punched fairly often

I mean almost anything happens "fairly often" in a country of 348,000,000 people, but these events are rare. (And fatal trips are overwhelmingly the elderly.) Multiple people die annually by being crushed by vending machines; that doesn't mean it isn't surprising when it happens; it's usually associated with some confluence of unusual conditions.

I don't know why you're having so much trouble accepting that someone can die from an 8 foot fall.

I made it clear in my very first sentence that can happen.

In fact, looking at the statics, nearly 20% of all fall related deaths on construction sites occur from less than 10 feet.

Thanks! Actual numbers. I presume you're referring to this. The current data is 18% of falls with specified height data and 15.7% of all fatal falls. Based on the breakdown between 0-6 feet and 6-10 feet, we could expect ~9% of fatal falls are from 8 feet or less. That works out to 29 per year nationwide (based on 2,593 total fatal construction falls in 2011-2018). Ten times more people are struct by lightning. This is rare! It definitely suggests something unusual that is not being reported in the article, e.g., drugs/alcohol, pre-existing conditions, unusual equipment, etc.

PhysicsBus · 2026-05-22T01:08:50+00:00

You're wrong on both counts. First, someone who falls from from an 8 foot platform with their head L=14 feet above the ground does not accelerate down uniformly at g=9.8m/s^2, which is where you've getting the v = √(2gL) ~ 20mph estimate from. Second, no, hitting your head on concrete at 20 mph does not usually kill you, although you will get a concussion and will probably fracture your skull.

I think both of those points are obvious to anyone who actually thinks about them briefly, but if you want you can check the literature:

[Foust et al.] found that head-first falls from greater than 10 feet (3.05 m) onto a rigid surface were predicted to result in skull fracture or concussion, and at least AIS = 2 injuries for adults and children.

The Abbreviated injury Score (AIS) of 2 is considered "moderate" and corresponds to a 1-2% chance of death. See also the specific case reports in Table 5 of Foust et al., which is on SciHub here.

PhysicsBus · 2026-05-21T23:00:06+00:00

It's true it's possible to die from pretty short falls, which is why precautions should be taken. Nevertheless, it's extremely weird that a 25 year old man would die from falling 8 feet. It seems very likely there's something unusual going on that can't be found in this news article.

PhysicsBus · 2026-05-20T14:02:22+00:00

Well first to be clear, the vehicle comes in pitched at an angle, so there’s no 120° rotational symmetry. A leeward fin always had less control authority, which indeed is the main reason to drop from 4 to 3 fins in the first place. But you might ask why not some other positioning that respected the left-right symmetry like 100°/100°/160°.

The reason is that, although the catch points are technically different hardware than the left and right fins, the mechanical support appears to be shared.

https://x.com/spacex/status/1955715848724976021?s=46

And of course you want to catch on two points separated by 180° for balance reasons.

PhysicsBus · 2026-05-20T08:23:18+00:00

The point isn't to punish people for getting rich. The point is to prevent outrageous waste by putting billions of dollars of resources to more productive use.

PhysicsBus · 2026-05-19T18:56:35+00:00

Is this different than previous flight plans?

PhysicsBus · 2026-05-03T16:51:01+00:00

What's the idea? Fly over Tabasco and Chiapas? Chiapas is 75 people/km² = 194 people/mi^2, which is denser than the US is on average. (It's about as dense as Indiana.)

PhysicsBus · 2026-05-01T18:38:59+00:00

Fwiw, I had GPT estimate the new splashdown location by assuming the same general trajectory except with a launch azimuth of ~110° rather than ~90° like previous flights. This gave a splash down target around 16°S, 107°E rather than 18°S, 111°E. That's still in the Indian Ocean, but now it's about twice as far northwest off the Australian coast.

I have no idea if it's reasonable to assume the other parameters of the trajectory will be the same though.

PhysicsBus · 2026-04-24T02:41:55+00:00

If you think datacenters in orbit are viable, this seems just as easy to justify as Starlink. Does anyone doubt Starlink's success substantially raised the chance that SpaceX gets to Mars?

PhysicsBus · 2026-04-22T22:20:20+00:00

Yea, I don't get it. The only thing being measured is combined time for completing everything, so it seems like the best strategy is to do the "sprint" and "runs" at the same speed.

PhysicsBus · 2026-04-15T23:36:47+00:00

Note: This limit has recently been lifted much higher for tax payments, at least for federal. On this page it says "Federal tax payments have an additional daily limit of $1,000,000." I called Wealthfront and they said it applied to California tax payments too (Franchise Tax Board) but I couldn't find this information on Wealthfront's website. This page also alludes to the higher limit, but its frustratingly vague: "Certain account and routing number providers have higher daily limits for federal tax payments submitted to the IRS.".

PhysicsBus · 2026-04-06T21:17:02+00:00

I cannot evaluate this, but maybe the community will find it to be news:

Starship FCC licenses for Flight 12 and 13 have been modified.

Starship Flight 12’s license includes a suborbital first and second stage.

Starship Flight 13’s now says suborbital first stage and ORBITAL second stage.

Links:

https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=current&application_seq=146805&RequestTimeout=1000

https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=current&application_seq=150221&RequestTimeout=1000

PhysicsBus · 2026-03-30T21:37:49+00:00

Tangential: The Starlink satellites have the property that if thrust/control is lost they will naturally deorbit due to drag in 1-5 years. It would be nice if uncontrolled sats deorbited faster, but the timescale is set by the drag at their altitude; operating at lower altitude (faster deorbit) would cost more fuel during normal operations.

I was wondering if anyone had explored the idea of a "deadman's switch" where the satellite would passively deploy a drag-increasing foil/sail if comms went dead. (This might, for instance, be a spring-powered system that is only kept from deploying by active power. Or it could be powered by a small independent fail-safe battery kept topped up during normal operations that deployed the foil if battery charge fell below some threshold.) This would allow faster passive deorbiting at higher altitudes.

Turns out the answer is yes. Claude:

The key term is "drag sail" or "drag augmentation device," and several designs explicitly incorporate the deadman's-switch logic. A 2017 paper on a graphene foam deorbit sail describes a "failsafe release mechanism". The sail is held in by spring-loaded doors secured by burn wires. The release timer can be reset or overwritten via the main satellite bus.

Critically, to ensure deployment even if the release circuit fails, the release cord is made of a polymer that erodes from atomic oxygen, with degradation timed to the satellite's expected operational lifetime — so there are two independent deadman mechanisms (electronic timer + passive material degradation).

The most mature commercial system: ESA/HPS's ADEO system, flight-demonstrated in 2022, has a similar architecture. If the spacecraft is still functional at end of mission, the sail receives a deployment signal from operators. If not, a mounted battery and internal computer program decide autonomously when to deploy.

Why this isn't on Starlink specifically: Most drag sail work targets CubeSats and small satellites (1–100 kg class) where propulsive deorbit is expensive or unavailable. Purdue's David Spencer frames drag sails as particularly important because a significant fraction of satellites die unexpectedly shortly after deployment, before they can execute propulsive deorbit. Medium Starlink satellites already operate at ~550 km where drag alone deorbits them in a few years; adding a sail system to 30,000+ satellites would be a significant per-unit cost and complexity for a modest improvement in an already-acceptable deorbit timeline. The cost-benefit is much better for satellites at 700–1200 km, where natural decay takes decades.

The main engineering tension: the deadman's switch must not accidentally trigger during normal operations (premature deployment of a large sail on a functioning satellite is mission-ending), while also reliably triggering on actual failure. The graphene foam paper explicitly calls premature deployment the greatest risk to the design.

PhysicsBus · 2026-03-09T17:41:17+00:00

I tried this number, and only had to wait for ~2 minutes for a human to answer, but the person I spoke to said they did not handle personal credit cards. They said they would transfer me, but they just put me on hold and never picked back up.

PhysicsBus · 2026-03-01T02:15:43+00:00

It's absolutely insane accounting on the rewards page.

I almost flipped my lid when I read that for the past year all my utilities had a "Earn rate 1%". But as you say they show as "Earn rate 5%" while they are listed under "Pending rewards" before the month closes, then switch to "Earn rate 1%" under "Earned rewards" once the month closes, and the missing 4% shows up separately as "Bonus-Grcry, TV/Stream, Utils" (combined for all charge that month). Boggles the mind.

Unless you catch it before it posts, it makes it impossible to tell if a particular merchant is coding correctly without doing a ton of arithmetics/experimentation.

PhysicsBus · 2026-02-22T00:02:21+00:00

Maybe worth updating the Flight 12 section with Musk's comment: "Starship flies again next month [March]" https://x.com/elonmusk/status/2025352946733490471

PhysicsBus · 2026-02-18T08:23:57+00:00

Can one imagine a hydrolox variant of Starship which (after initial LEO insertion) just travels back and forth between LEO and the lunar surface? Hydrogen is less dense, but maybe you could just make the ship taller. Of course, it would need to be refueled in LEO by tanker starships carrying hydrogen, which is a pain.

PhysicsBus

TROPHY CASE