Science News Thread (for articles that don't relate to ongoing discussions)

[JoeSchmuckatelli]

For those interested - the volcano on Iceland is rated as 'imminent'. 

Sky news is streaming (for those wanting to watch the last hours of a residential community). 

 

https://news.sky.com/story/iceland-volcano-live-updates-cracks-appear-in-roads-amid-fears-of-imminent-volcanic-eruption-13008004

 

[kerbiloid]

I hope, they already have invented a stylish Icelandic name for it. 

Eyjafjallajökull is usual now.

[AckSed]

Not new news, but I found an interesting article about photonic laser thrusters and their potential to create a 'laser highway': https://spacesettlementprogress.com/enabling-a-multiplanetary-civilization-with-photonic-laser-thrusters/

Essentially, it uses a thin laser amplification medium and 99.99% reflective dielectric mirror on the powering spacecraft, with an identical mirror on the target spacecraft to bounce the laser light back and forth thousands of times, essentially turning it into a very long laser cavity itself. In the demonstration below a 500 watt infra-red laser, incident on a mock 750g cubesat, acts like a 500 kilowatt laser, with a measurable increase in thrust that pushes the satellite away and decelerates it. It's just 3.3 milliNewtons, but like a solar sail, this is continuous thrust that does not use propellant and has extremely high velocity.

Because I know people will ask, the researcher says it is "insensitive to mirror motions". I haven't been able to access the journal he cites, though. (Y.K. Bae, Journal of Propulsion and Power, Vol. 37, pp. 400-407 (2021))

The slides and audio on this presentation are available, and they propose that a small 1-ton spacecraft (50% of that payload) with a 30m mirror and a 10 MW laser could reach the Moon in 20 hours with a beam incidence time of 6.8 hours - a delta-V of 11.6 km/s. The same mass with a 50m mirror and a gigawatt laser could reach Mars in 18.5 days and an incidence time of 1.2 hours - a phenomenal 141 km/s (with an acceleration of 3.4 gravities!). It presumes you sent on another gigawatt laser ahead to Mars so you could slow down. Or use that Mars laser and a new probe to do a flyby of the asteroids in 6-18 days, or Jupiter and its moons in 45 days. Impressive.

It grew out of earlier research funded by NASA's NIAC, where the researcher was looking at formation-flying satellites that used laser light from the 'mother' or the 'flock' to move around in orbit. Thus one spacecraft could keep multiple others in orbit: https://www.nasa.gov/general/propellantless-spacecraft-formation-flying-and-maneuvering-with-photonic-laser-thrusters/

Quote

Our original emphasis was on propellant-free nanometer accuracy tethered formation flying, however, during our study on photon thruster demonstration, we discovered that our photon thruster (Photonic Laser Thruster, PLT) has a much larger potential in NASA mission applications than precision tethered formation flying. The potential resulted from a surprising discovery on the extraordinary stability of PLT against dynamic motions of mirrors in our unique active optical cavity, which may enable in space propulsion for an extremely wide range of unprecedented NASA missions. For example, 10,000 times recycling of photons with 15 kilo-watt input laser power, which can be delivered by a 100 kW solar panel would produce up to 1 N of photon thrust, which is sufficient to enable these missions.

 

[DDE]

1 minute ago, AckSed said:

Not new news, but I found an interesting article about photonic laser thrusters and their potential to create a 'laser highway': https://spacesettlementprogress.com/enabling-a-multiplanetary-civilization-with-photonic-laser-thrusters/

Essentially, it uses a thin laser amplification medium and 99.99% reflective dielectric mirror on the powering spacecraft, with an identical mirror on the target spacecraft to bounce the laser light back and forth thousands of times, essentially turning it into a very long laser cavity itself. In the demonstration below a 500 watt infra-red laser, incident on a mock 750g cubesat, acts like a 500 kilowatt laser, with a measurable increase in thrust that pushes the satellite away and decelerates it. It's just 3.3 milliNewtons, but like a solar sail, this is continuous thrust that does not use propellant and has extremely high velocity.

Because I know people will ask, the researcher says it is "insensitive to mirror motions". I haven't been able to access the journal he cites, though. (Y.K. Bae, Journal of Propulsion and Power, Vol. 37, pp. 400-407 (2021))

The slides and audio on this presentation are available, and they propose that a small 1-ton spacecraft (50% of that payload) with a 30m mirror and a 10 MW laser could reach the Moon in 20 hours with a beam incidence time of 6.8 hours - a delta-V of 11.6 km/s. The same mass with a 50m mirror and a gigawatt laser could reach Mars in 18.5 days and an incidence time of 1.2 hours - a phenomenal 141 km/s (with an acceleration of 3.4 gravities!). It presumes you sent on another gigawatt laser ahead to Mars so you could slow down. Or use that Mars laser and a new probe to do a flyby of the asteroids in 6-18 days, or Jupiter and its moons in 45 days. Impressive.

It grew out of earlier research funded by NASA's NIAC, where the researcher was looking at formation-flying satellites that used laser light from the 'mother' or the 'flock' to move around in orbit. Thus one spacecraft could keep multiple others in orbit: https://www.nasa.gov/general/propellantless-spacecraft-formation-flying-and-maneuvering-with-photonic-laser-thrusters/

 

I can't drive off the immediate first impression...

...but it's basically a recuperation mechanism, isn't it?

[AckSed]

3 minutes ago, DDE said:

I can't drive off the immediate first impression...

...but it's basically a recuperation mechanism, isn't it?

Yes. The stated future performance is when it can bounce the photons back and forth 10,000 times. Currently, it's roughly 1000 times or so, which at 6.6mN per kilowatt is still better than most solar sails and micro-thrusters, and for a much lesser opportunity and deployment cost.

There's nothing stopping you from encoding information into that laser both ways, either.

[Superluminal Gremlin]

Acceleration over time would slow down, right? Lasers get less powerful the further they are away. Or only in atmospheres (cos of diffraction, refraction, ect).

[darthgently]

47 minutes ago, Superluminal Gremlin said:

Acceleration over time would slow down, right? Lasers get less powerful the further they are away. Or only in atmospheres (cos of diffraction, refraction, ect).

The beams lose coherence and focus with distance iirc.  Which would seem to make it harder and harder to bounce all of the beam back to the other mirror at extreme growing distance, as well as the acceleration issue you bring up.  Still, as Acksed notes, it is an upgrade to the normal laser sail concept

[AckSed]

It does make it harder but... Go check out the presentation PDF I linked. In it there's a table of how long the laser beam is incident on the outgoing spacecraft and over what distance - a boost phase, in other words.

For the Earth-Moon boost, that's 6.8 hours and 10,000 km. For Mars, it's 1.2 hours and 30,000km. The spacecraft will then flip and be decelerated by a laser on the surface or in orbit. As I said, the deceleration hardware has to be sent on ahead. The electrical requirements are high but not onerous: 10 megawatts. E.g. the iROSA solar panel arrays on the ISS generate 20 kW and mass 325 kg. Fifty of those or similar would be gargantuan, yes, but it's mass you only have to take with you once. Or build with ISRU on the lunar surface. Mars would take a gigawatt nuclear reactor, but a nuclear-electric rocket/laser powerplant could self-deliver itself.

It does tickle me that these future PLTs follow near-torchship trajectories and literally have no brakes.

Edited November 21, 2023 by AckSed

[kerbiloid]

https://attheu.utah.edu/facultystaff/cosmic-ray-2023/

They detected a super-energetical particle, similar to the previously caught Oh-My-God particle, and named it "Amaterasu particle".

P.S.
Previously it was a particle of god, now they know of which exactly god.
Cuz fizzix.

P.P.S.
Iirc, some earlier the Higgs boson was "a particle of God".

Feels, like soon they will start counting angels on the tip of a quark.

[SunlitZelkova]

4 hours ago, kerbiloid said:

https://attheu.utah.edu/facultystaff/cosmic-ray-2023/

They detected a super-energetical particle, similar to the previously caught Oh-My-God particle, and named it "Amaterasu particle".

P.S.
Previously it was a particle of god, now they know of which exactly god.
Cuz fizzix.

P.P.S.
Iirc, some earlier the Higgs boson was "a particle of God".

Feels, like soon they will start counting angels on the tip of a quark.

Now we need to test the Imperial family to see if they contain this particle, and we can prove if they are descended from the Sun Goddess herself.

[Codraroll]

On 11/24/2023 at 6:26 AM, kerbiloid said:

Iirc, some earlier the Higgs boson was "a particle of God".

Only because Higgs' editor didn't like swearing. Higgs originally referred to it as "that goddamn particle", which was changed by the editor.

[kerbiloid]

1 hour ago, Codraroll said:

Only because Higgs' editor didn't like swearing. Higgs originally referred to it as "that goddamn particle", which was changed by the editor.

Now they know, which god's damnation they had happily evaded from, thanks to the editor good manners.

[DDE]

Hello, I'm a time-traveller and I've dropped a cigarette lighter in the Jurassic. Will there be any evidence? I know that fossils are the result of a convoluted process that requires specific circumstances and a whole lot of luck. What about other materials?

[SunlitZelkova]

50 minutes ago, DDE said:

Hello, I'm a time-traveller and I've dropped a cigarette lighter in the Jurassic. Will there be any evidence? I know that fossils are the result of a convoluted process that requires specific circumstances and a whole lot of luck. What about other materials?

Well, considering the foundations of buildings of the world’s major cities are expected to eventually become part of the strata and be objects of research for far future archaeologists, I would say fossilization is possible for at least some nonorganic materials.

Source: The Earth After Us, What legacy will we leave in the rocks? by Jan Zalasiewicz.

[kerbiloid]

3 hours ago, DDE said:

Hello, I'm a time-traveller and I've dropped a cigarette lighter in the Jurassic. Will there be any evidence? I know that fossils are the result of a convoluted process that requires specific circumstances and a whole lot of luck. What about other materials?

Now they mine oil from dinosaur remains.

[darthgently]

7 hours ago, DDE said:

Hello, I'm a time-traveller and I've dropped a cigarette lighter in the Jurassic. Will there be any evidence? I know that fossils are the result of a convoluted process that requires specific circumstances and a whole lot of luck. What about other materials?

The timeline will be completely altered as dinosaurs with thumbs discover fire before primates

[kerbiloid]

And the roaches discover the roaches.

Spoiler

 

[magnemoe]

On 12/1/2023 at 8:32 AM, DDE said:

Hello, I'm a time-traveller and I've dropped a cigarette lighter in the Jurassic. Will there be any evidence? I know that fossils are the result of a convoluted process that requires specific circumstances and a whole lot of luck. What about other materials?

Problem would be to find it,  earth is pretty large and just some square kilometers has been execrated for science and most of it is archaeology. 
So it could easy been an good size alien base on earth back during the age of the dinosaurs and we never notice.
But some might have dropped something. 

The idea of an earlier civilization as advanced as our, no we leave an large footprint, we makes mines in ore deposits they would used, mining tunnels who is then filled with other sediments would be very obvious. No we don't leave behind much bones but stuff like aluminium engine blocks who don't break down easy and if so will leave an fossil. 

[kerbiloid]

Zoo activists: "Stop wearing natural fur coats! Wear the plastic ones!"

Eco activists: "Are you idiots? The plastic ones won't decay for five centuries!"

[AckSed]

tl;dw Magnesium alloys have advanced significantly in fire-resistance and corrosion resistance, and new casting techniques from Idra are in development that allow for large castings to be made, reducing weight by up to 25% on all sorts of things - electronics, phones, cars, airplanes, non-structural rocket parts.

The cool thing is that the same element that gives corrosion resistance to magnesium - calcium - is also one of the three that gives fire resistance. An alloy of pure Mg with 0.15% of Ca survived 180 days of submersion in saltwater that was 3.5% NaCl by weight, with minimal degradation. That's it. That's all you need to make a lightweight metal resistant enough they nicknamed it "stainless magnesium":

Spoiler

E21 (Elektron 21) and AZ91 are aerospace Mg alloys.

The addition of zinc and calcium, with yttrium, gadolinium or ytterbium added in trace to marginal quantities, grants the other alloy in the video its ability to melt before it ever catches fire. In fact, it is even approved by the FAA for use in seat structures. They tried to light it in an oil fire and it melted after 60+ seconds, yes, but plain would not burn.

Finally, Idra's thixotopic shot casting (chunks of the magnesium alloy are kept somewhat below melting point and, like plastic, forced into the mould with a screw) allows for big parts to be made in one shot. They also release from the mould much easier than aluminium parts.

[Vanamonde]

An asteroid will pass in front of Betelgeuse tomorrow. 

https://apnews.com/article/asteroid-star-eclipse-betelgeuse-b9e3796c1ca915afdb84ed41509da9c8

[JoeSchmuckatelli]

16 hours ago, Vanamonde said:

An asteroid will pass in front of Betelgeuse tomorrow. 

 

Couple of brain twisting things from reading the article ; stars look tiny (pixel-ish) even though we know they are impossibly huge. The light I might see while looking at Orion & Betelgeuse from Washington is not the same light I might see at the same time from Florida.  The entire planet must be bathed in Betelgeuse light. 

The asteroid is comparatively tiny - but large enough to occlude the light in a swath (the article doesn't say, but perhaps hundreds of miles wide or dozens.  It doesn't say.) across the face of the planet.  Some will see the star wink out - most never could. 

What a wonder is this universe! 

Edited December 9, 2023 by JoeSchmuckatelli

[Superfluous J]

5 hours ago, JoeSchmuckatelli said:

Couple of brain twisting things from reading the article ; stars look tiny (pixel-ish) even though we know they are impossibly huge. The light I might see while looking at Orion & Betelgeuse is not the same light I might see at the same time from Florida.  The entire planet must be bathed in Betelgeuse light.

It's worse (better? Neater, at any rate) to think about the sheer volume of photons that Betelgeuse (and every star) is giving off ALL the time (for millions if not billions of years) to be visible from pretty much anywhere inside a huge sphere that is surely much, much larger than the distance between it and us.

And those photons that are not meant for our eyes are flying around anyway in all directions, from all the stars (and other stuff ofc).

Space is empty? Hardly.

[DDE]

16 hours ago, AckSed said:

yttrium, gadolinium or ytterbium

That doesn't exactly scream "affordable seat structure material".

[AckSed]

6 hours ago, DDE said:

That doesn't exactly scream "affordable seat structure material".

All right, I'll exert the effort as well as sharing a cool thing.

Yttrium's market price per kg is 33 USD, or $33,000 per metric ton.

It's a by-product of rare-earth processing, and there's a dedicated supply chain because it is used in some catalysts and as a dopant for laser gain mediums. Looking at the patent reveals that the amount needed to make it fireproof is 0.05-0.6%. If I assume this is by weight, then in an alloy of 95% Magnesium (~$3,000 per metric ton), 0.15% Calcium (~$9,900 per metric ton of metal) and 4.8% Zinc (~$2,900 per metric ton), 0.05% Yttrium adds roughly $1650 to the price of a metric ton.

Mash those other numbers together:

95% of 3000 = 2850

0.15% of 9900 = 14.85

4.8% of 2900 = 139.20

2850 + 14.85 + 139.20 + 1650 = $4,654.05 USD per metric ton

Now, this fire-proof, corrosion-proof wonder-alloy (we'll call it AirMag) is pricey, no question. A normal AZ91D magnesium alloy is $3,100 USD per mt. But remember our weight savings - 20-25% over aluminium alloys. Taking into account rising airline fuel costs and the built-in fire-safety, it may close as a 'spend money now to stop spending money later' business case. Let's work it out.

I don't know how much airline seats weigh. We will assume the framework of each one is 5kg and made of aluminium alloy. An Airbus 380 hovers around 460-510 seats depending on airline. It also burns 11-12 metric tons of fuel per hour, for $816 per mt at UK 2022 prices. That's $8,932-9,744 USD per hour. (Fuel isn't cheap here.)

If we take 500 seats as a round number, that's 2.5 mt just in seats.

Using AirMag we save 20% of the mass, or 500kg, for approximately 3 times the price.

Every kg we save in airplane weight saves 0.02-0.03 kg of fuel per 1,000km.

Quote

To reduce the cost per available seat kilometre (CASK) of ~6 €cent by 1 ‰, the weight needs to be reduced by ~300 to 1,000 kg (structural or operational), depending on the aircraft type.

So although we're on the right track regarding weight savings, that's just 10-15kg of fuel or $8.12-12.18 saved per 1000km flight in fuel.

Now I don't know whether this margin would be an acceptable trade, but I've already spent two hours on this so I will admit that for airlines, it's weak. Not insignificant, as airliners cost a bundle, and depending on fuel prices, carbon emissions and under differing circumstances a campaign of lightweighting on the seats would be a drop in the bucket compared to the millions spent on building the things. But a retrofit would need a better salesman than I.