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Fighteer Lost in Space from The Time Vortex (Time Abyss) Relationship Status: TV Tropes ruined my love life
Lost in Space
#9451: Nov 29th 2021 at 7:57:32 AM

  • If the "no-hair" theorem is correct, then Hawking radiation is not entangled with anything, but then quantum information is invariably destroyed when the black hole evaporates. This is paradoxical.
  • If Hawking radiation is entangled with the interior topology of the black hole, then we have a similar problem because that topology is nowhere to be found after total evaporation.

These two paradoxes can be resolved if the black hole interior flows into some alternate region of spacetime that is causally disconnected from the exterior. When the black hole evaporates, there is no longer a path from our spacetime to the other one, but it still remains along with any entanglement.

On the other hand, if all quantum information that falls into a black hole is preserved on its event horizon, such as in the holographic principle or the "fuzzball" theorem, then there is no paradox because that information is encoded in Hawking radiation and remains causally connected all the way to the end. There is no "interior" that matters to us.

At least, this is my best understanding of these ideas without doing the actual math.

Edited by Fighteer on Nov 29th 2021 at 10:58:56 AM

"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"
SeptimusHeap from Switzerland (Edited uphill both ways) Relationship Status: Mu
#9452: Nov 29th 2021 at 9:37:41 AM

Anyway, I am inclined to agree with demarquis that discussions about energy conditions are among the most confusing in physics. And arguably the least productive too since they have virtually no empirical footing.

I am more interested in exoplanet habitability. For example, how events in the mantle of a moderately volcanically active moon might restore an atmosphere after it was lost. And how long an ocean would have to exist for life to originate in it. Or even in no ocean.

"For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled." - Richard Feynman
Fighteer Lost in Space from The Time Vortex (Time Abyss) Relationship Status: TV Tropes ruined my love life
Lost in Space
#9453: Nov 29th 2021 at 9:44:17 AM

Well, if we want to be pedantic, exoplanet habitability is very nearly as esoteric a question as energy conditions because in both cases we have no hope of empirically testing them for a very, very long time.

At least with the former, we can potentially detect life-bearing planets via transit spectrography, but only in very particular cases. Detecting the potential for life is much harder, and of course this precludes the possibility of alien life coming to visit us or sending us messages.

It is my personal hypothesis that the most promising idea for confirming extrasolar life is the Breakthrough Starshot program or something similar: postage-stamp-sized probes boosted to relativistic velocity by lasers and sent en masse to neighboring solar systems in the hopes that they will transmit usable data as they blaze through.

At 10 percent of the speed of light, it would take ~43 years from launch to get to Proxima Centauri and an additional 4.3 years or so to receive the signal back. Given how long it will probably take us to get to the point of launching these probes, this puts us into the next century at the earliest.

Edited by Fighteer on Nov 29th 2021 at 12:49:27 PM

"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"
SeptimusHeap from Switzerland (Edited uphill both ways) Relationship Status: Mu
#9454: Nov 29th 2021 at 11:17:38 AM

Yeah, I've read about the Breakthrough project. I am guessing, if turns out that Proxima Centauri b and/or the TRAPPIST-1 planets or any other planet within the first few parsecs have atmospheres that aren't Venus-like hot or Jupiter-like stellar it might draw some momentum to these projects.

"For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled." - Richard Feynman
amitakartok Since: Feb, 2010 Relationship Status: Don't hug me; I'm scared
#9455: Nov 29th 2021 at 12:01:47 PM

A French company successfully tested an ion engine design that runs on iodine instead of xenon, making it substantially cheaper and simpler due to the fuel not requiring pressurized tanks. On the other hand, corrosion is a serious problem that requires ceramic coating of drive components.

Fighteer Lost in Space from The Time Vortex (Time Abyss) Relationship Status: TV Tropes ruined my love life
Lost in Space
#9456: Nov 29th 2021 at 12:03:27 PM

What's the specific impulse difference? I know that SpaceX has been using krypton ion thrusters for its Starlink satellites despite the lower efficiency because krypton is much more abundant (and thus cheaper) than xenon.

"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"
amitakartok Since: Feb, 2010 Relationship Status: Don't hug me; I'm scared
#9457: Nov 29th 2021 at 12:06:25 PM

“Iodine is significantly more abundant and cheaper than xenon, and has the added advantage that it can be stored unpressurized as a solid”. Xenon by comparison must be stored under high-pressure (typically 100-200x atmospheric pressure). Iodine also has a storage density almost 3x higher than xenon (and 9x higher than krypton). This enables significant simplification and miniaturization of propulsion systems. “ThrustMe has developed a revolutionary propulsion system with an iodine ion thruster, the NPT30-I2, which includes all needed subsystems and fits within a single package of roughly 10 cm x 10 cm x 10 cm” says Dmytro. Comparison with xenon shows that iodine gives an almost 50% performance enhancement.

Apparently this was the payload of the Long March 6 rocket that launched on Nov 6.

Edited by amitakartok on Nov 29th 2021 at 9:08:07 PM

amitakartok Since: Feb, 2010 Relationship Status: Don't hug me; I'm scared
#9458: Nov 29th 2021 at 12:12:35 PM

Found it. The product page states it comes in two sizes that pack an Isp of 5500 and 9500, respectively, and takes 3 minutes to go from cold start to full thrust.

For reference, Wikipedia says the DART probe's ion engine has an Isp of 4170.

Edited by amitakartok on Nov 29th 2021 at 9:16:08 PM

Fighteer Lost in Space from The Time Vortex (Time Abyss) Relationship Status: TV Tropes ruined my love life
Lost in Space
#9459: Nov 29th 2021 at 12:15:43 PM

Compared with krypton at ~5000 s, that's extremely good. And this is a Chinese demonstration? [shakes head]

The rest of the world had better get a move on.

"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"
SeptimusHeap from Switzerland (Edited uphill both ways) Relationship Status: Mu
#9460: Nov 29th 2021 at 12:19:12 PM

Does the corrosion make problems.

"For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled." - Richard Feynman
amitakartok Since: Feb, 2010 Relationship Status: Don't hug me; I'm scared
#9461: Nov 29th 2021 at 12:33:06 PM

[up][up]The cubesat said engine was mounted onto (Beihangkongshi-1) is built and operated by the Chinese Spacety company, but the engine itself is French and ThrustMe even got a grant from the EU in 2018 for the project. So it's closer to being an international cooperation.

Also, the sat was launched last year, not this year. My mistake. Spacety has also launched a second satellite since that uses the same engine to eventually deorbit itself at the end of its service life.

[up]Based on its position in the periodic table (same chemical group as chlorine and fluorine), I'd hazard a guess that ionized iodine is a really nasty oxidizer that would eat away the reaction chamber over time.

Edited by amitakartok on Nov 29th 2021 at 9:34:58 PM

SeptimusHeap from Switzerland (Edited uphill both ways) Relationship Status: Mu
#9462: Nov 29th 2021 at 12:54:48 PM

Incidentally, I was thinking how likely it is that there is life on Europa or Enceladus that does not have a common ancestor with Earth's. I think there are probes on the way there, right?

"For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled." - Richard Feynman
Fighteer Lost in Space from The Time Vortex (Time Abyss) Relationship Status: TV Tropes ruined my love life
Lost in Space
#9463: Nov 29th 2021 at 12:57:42 PM

Europa Clipper is in development with an anticipated launch date in 2024 atop a SpaceX Falcon Heavy rocket. It's designed specifically to look for signs of life there.

"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"
SeptimusHeap from Switzerland (Edited uphill both ways) Relationship Status: Mu
#9464: Nov 29th 2021 at 1:10:55 PM

...you know, on Wikipedia it says that Congress initially wanted to launch it on the SLS. Some well-placed cronies?

"For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled." - Richard Feynman
Fighteer Lost in Space from The Time Vortex (Time Abyss) Relationship Status: TV Tropes ruined my love life
Lost in Space
#9465: Nov 29th 2021 at 1:12:48 PM

Oh ho ho ho, there's some fun drama in that story. Yes, it was supposed to go on SLS because of Congressional cronyism, but as that rocket got delayed again and again, Falcon Heavy emerged as a clearly superior solution. It will take two years longer from launch to get to Europa because of gravity assists, but the mission price is something like a tenth that of SLS and it will be able to launch at least two years earlier, so the times balance out.

Clipper will be the most massive spacecraft ever sent beyond the Earth-Moon Hill sphere note  and it will need every single scrap of delta-V that Falcon Heavy can give it. Thus, it will launch in fully expendable mode.

Edited by Fighteer on Nov 29th 2021 at 7:45:17 AM

"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"
Fighteer Lost in Space from The Time Vortex (Time Abyss) Relationship Status: TV Tropes ruined my love life
Lost in Space
#9466: Nov 29th 2021 at 5:49:15 PM

Back on those iodine ion drives, I put 5000 as the specific impulse of krypton, but that's probably way over its actual value in the Hall effect thrusters employed on Starlink satellites. It's devilishly hard to get precise values but the Wikipedia article suggests values between 1000 and 3000.

A practical value of 5500 would be pretty amazing if they can deal with the corrosivity of the propellant.


In launch schedule news, that Chinese Galactic Energy launch was postponed again to NET December, so I'm going to ignore it until it actually happens... it's not like we'll get any live coverage.

This means that next up to bat is SpaceX Starlink Group 4-3 on Wednesday at 23:20 UTC (6:20 PM EST). This one I'll be able to watch live without muting it during meetings or staying up late.

Launching barely an hour later will be an Arianespace Soyuz rocket with two Galileo navigation satellites. After that we get Virgin Orbit's fourth launch.


Of course, the main event tomorrow will be the spacewalk by astronauts Thomas Marshburn and Kayla Barron aboard the ISS to replace a faulty antenna. It should start at 12:10 UTC (7:10 AM EST) and will be streamed live here. Tune in for the drama and the excitement! Yeah, no. Drama and excitement are what we don't want.

"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"
Fighteer Lost in Space from The Time Vortex (Time Abyss) Relationship Status: TV Tropes ruined my love life
Lost in Space
#9467: Nov 30th 2021 at 4:11:09 AM

Today's spacewalk has been postponed due to a possible collision risk for the ISS with a debris object. The object's identity has not been specified as far as I know, so it's not clear if it's from the recent Russian ASAT test or something else.

The NASA press release has been updated accordingly.


Space Explored: Elon Musk says SpaceX could face ‘genuine risk of bankruptcy’ from Starship engine production

A leaked email from Elon Musk to SpaceX employees purports to show a rush to address critical issues with Raptor engine production lest the company face bankruptcy. Space Explored has published it as a scoop. While assessing the credibility of the email, several things must be noted.

  • SpaceX recently fired its vice president of propulsion due to a "lack of progress" on engine manufacturing.
  • The email states that achieving Starship flight rates of "once every two weeks" is necessary for "next year", meaning 2022.
    • This is odd because Musk has previously stated that they are targeting as many as ten flights in 2022, most of which would be for testing purposes. There's quite a difference between ten and twenty-six. We haven't been expecting operational flights with payloads until 2023 and the FAA environmental assessment that is currently under review doesn't support the indicated flight rate.
  • The email states that Starlink V1 is unprofitable, which is almost certainly true, and that "V2 is strong", meaning the second-generation satellites that are intended to launch on Starship. Without Starship, it won't be possible to put them in orbit in the necessary volume.
  • The email states that Musk returned from his holiday to work at Hawthorne and he expected all employees who were able to do to the same.
  • The email states that without fixing Raptor issues, SpaceX could go bankrupt, referring to the immense investment in Starlink and the need to get profits from it.
    • This strikes me as a weird argument since Musk has access to immense personal financial resources and can raise capital basically for asking. Further, if the company were really facing bankruptcy, NASA and its other major partners would have a significant interest.
  • Lastly, SpaceX is building an engine factory at McGregor, TX, which is intended to support high-volume production. Until this is complete I wouldn't expect a massive improvement in build rate.

All in all, while the tone is plausible, I'd like to see some confirmation.

Edited by Fighteer on Nov 30th 2021 at 7:14:19 AM

"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"
petersohn from Earth, Solar System (Long Runner) Relationship Status: Hiding
#9468: Nov 30th 2021 at 4:28:33 AM

Didn't SpaceX intend to fund Starship development from Starlink's profits? If the first generation of Starlink satellites are unprofitable, then something must have gone really wrong with their calculations.

Fjón þvæ ég af mér fjanda minna rán og reiði ríkra manna.
Fighteer Lost in Space from The Time Vortex (Time Abyss) Relationship Status: TV Tropes ruined my love life
Lost in Space
#9469: Nov 30th 2021 at 4:33:17 AM

No, Starship is definitely necessary to support high-volume Starlink launches. That was going to happen no matter what. The future profits from Starlink are intended to support Mars colonization, which will require at least a thousand Starships. It's synergistic.

Edited by Fighteer on Nov 30th 2021 at 7:33:44 AM

"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"
Fighteer Lost in Space from The Time Vortex (Time Abyss) Relationship Status: TV Tropes ruined my love life
Lost in Space
#9470: Nov 30th 2021 at 7:39:27 AM

NASA's Office of the Inspector General (OIG) has released a report (PDF) on the status of the International Space Station and the plan to replace it by 2030 via the Commercial LEO Destinations (CLD) program.

OIG expects "significant challenges" with this plan, particularly in avoiding a gap between the end of life of the ISS and the deployment of commercial space stations. Jeff Foust tweets about the report highlighting issues with the Zvezda module, which according to models should not have experienced the types of cracking that are currently being observed. This calls into question the long-term integrity of the other elements of the station, or at least of that specific module.

Edited by Fighteer on Nov 30th 2021 at 10:48:24 AM

"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"
amitakartok Since: Feb, 2010 Relationship Status: Don't hug me; I'm scared
#9471: Nov 30th 2021 at 7:47:25 AM

Can't they decommission the Zvezda?

Fighteer Lost in Space from The Time Vortex (Time Abyss) Relationship Status: TV Tropes ruined my love life
Lost in Space
#9472: Nov 30th 2021 at 7:48:48 AM

No, it's a core module. They'd have to disassemble half the station, I think. Yeah, look here. Zvezda is the hub for two of the solar arrays, the Poisk airlock, and the Nauka lab.


Ars Technica: Russia threatens criminal charges against a NASA astronaut

This is a continuation of that 2018 incident in which a hole was found in a Soyuz spacecraft docked to the International Space Station. Roscosmos has been chest-thumping about the incident ever since, suggesting that it was sabotage from NASA astronaut Serena Auñón-Chancellor. NASA contends, citing Russian engineering reports, that the hole was caused by a ground technician and improperly repaired prior to launch.

Now, Roscosmos claims that it has provided the results of its "investigation" to Russian law enforcement officials. A new article in Russian media suggests that Auñón-Chancellor drilled the hole as revenge over a "failed romantic relationship". NASA cites its own records as definitive refutation of these claims since it tracks the positions of its astronauts aboard ISS at all times.

It is unclear what Russia hopes to gain from these accusations. Roscosmos is in the middle of negotiations for an astronaut exchange program on Soyuz and Crew Dragon and has recently launched two new modules for the ISS. However, it had two highly publicized incidents recently in which improper thruster firings caused loss of attitude control on the station, and even more recently Russia's military destroyed a defunct satellite in an ASAT test, threatening the station with debris.

This sort of grandstanding is often used to deflect from national embarrassments.

Edited by Fighteer on Nov 30th 2021 at 10:53:35 AM

"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"
Smeagol17 (4 Score & 7 Years Ago)
#9473: Nov 30th 2021 at 8:29:18 AM

I don't think anyone who knows or cares about such things can be "deflected" by some unsubstantiated allegation. If there is nothing there, they just will remind people of incident that was unpleasant mainly for Roskosmos.

Fighteer Lost in Space from The Time Vortex (Time Abyss) Relationship Status: TV Tropes ruined my love life
Lost in Space
#9474: Nov 30th 2021 at 8:38:21 AM

Yeah, so why are they making a big deal of it? They have to know it's BS, or at least that NASA would never subject one of its own astronauts to humiliation and/or prosecution on the basis of a crazy conspiracy theory without definitive proof.

Edited by Fighteer on Nov 30th 2021 at 11:39:40 AM

"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"
DeMarquis (4 Score & 7 Years Ago)
#9475: Nov 30th 2021 at 11:08:00 AM

Asking "Why did the Russians do X?" tends to be a futile exercise. Half the time I don't think even they know.

I'm done trying to sound smart. "Clear" is the new smart.

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