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Wednesday, November 24, 2021

THE LAUNCHED DART!

DART spacecraft communicates with NASA (by @sciencemug)
DART spacecraft communicates with NASA (by @sciencemug)
[NASA logo pic, the DART spacecraft pic and the starry background pic are in the public domain
,
(source: Wikimedia Commons); adapted by @sciencemug]

 

Soo, dear reader, today (24-Nov-2021) the DART (Double Asteroid Redirection Test) Mission launched. Developed and led for NASA by the Johns Hopkins Applied Physics Laboratory (APL), DART launched at 6:21 p.m. GMT, from the Space Launch Complex 4 East at Vandenberg Space Force Base in California, USA. The payload was carried by a SpaceX Falcon 9 rocket.

The mission falls under the umbrella of NASA's Planetary Defense Coordination Office (PDCO), and it is the first test of "the kinetic impactor technique to change the motion of an asteroid in space" (see). In other words the NASA's brains, on behalf of humanity, will try, for the first time ever, to hit a space object with a man-made object in order to change its (the space one's, that is) course, and therefore to see if this is a sound strategy for preventing the Earth from getting hit by a space rock et al, and related havoc.

The DART mission's target is a 160 meters in size moonlet, Dimorphos, that orbits, at just over one km distance, the 780 meters in diameter near-Earth asteroid (65803), aka Didymos. So, Didymos and Dimorphos are a binary system, and DART spacecraft "will intercept [Dimorphos] in late September 2022, when the Didymos system is within 11 million kilometers of Earth" (see).

Although its innovative solar panels (the Deployable Space Systems Roll-Out Solar Arrays, aka ROSA, that, by DART, are going to be deployed in deep space for the first time) measure 8.6 meters by 2.3 meters, DART spacecraft per se has just the dimensions of a small US car (that is, probably, of a big European car...). But DART will strike the binary system at the impressive velocity of about 6.6 Km/s (meaning roughly 24000 Km/h or, for you, stubborn impractical non-SI users, 14800 miles per hour), meaning 20 or so times the speed of sound, meaning, dear reader, that, when the hit happens, a looot of energy will be released up there! 

This impact generated energy, scientist think, will indeed be enough to "change the speed of the moonlet in its orbit around the main body [i.e. Didymos] by a fraction of one percent, but this will change the orbital period of the moonlet by several minutes - enough to be observed and measured using telescopes on Earth" (see). In other words, the event will be powerful enough to eventually change the asteroid system's course, and, ultimately, it will prove that the kinetic impactor technique can be used with success to deflect something similar to Didymos that, unlike it and its tiny satellite, be someday actually rushing toward Earth.

By the way, dear reader, the whole smash&crash fuss will be witnessed, at close but safe distance, by the small LICIACube CubeSat (Light Italian Cubesat for Imaging of Asteroids) built by the Italian Space Agency (ASI), and released by DART spacecraft itself shortly before its rough demise.

The DART spacecraft, besides, is packed with state-of-the-art tech, like its NASA’s Evolutionary Xenon Thruster — Commercial (NEXT–C) ion engine, an electric propulsion system, its SMART Nav navigation algorithm for real time autonomous targeting of the Didymos system, and, last but not at all least, its only instrument, the Didymos Reconnaissance and Asteroid Camera for Optical navigation, aka DRACO. This is a camera that will take fancy pics of the asteroid system ("better than 20 cm/pixel at impact" (see)), but, above all, that, right before the impact, will feed the SMART NAV the necessary images to choose the right target, that is to identify and distinguish between Dimorphos (to hit) and Didymos (not to hit).

Well, dear reader, that's all for now. Let's wish DART mission's success, so that y'all, on Earth, be a little bit safer!

The comics are a rendering of what this dumb blog figures NASA's and DART spacecraft's communications have probably been, and will possibly be.

Ciao!

DART spacecraft communicates with NASA nad bets (by @sciencemug)
DART spacecraft communicates with NASA (by @sciencemug)
[NASA logo pic and the DART spacecraft & asteroids pic are in the public domain
,
(source: Wikimedia Commons); the target pic by Karen Arnold
is under the CC0 Public Domain license, (source: Public Domain Pictures); adapted by @sciencemug]

Friday, October 29, 2021

THE TRUE REASON WHY DOGS CAN READ HUMANS!

Doggy sick by (@sciencemug)
Human mind's sick dog reader (by @sciencemug)
[The
dog pic by Matthew Henry is a free one (source: Unsplash); adapted by @sciencemug]

Soo, dear reader, five researchers from different German universities (aka the Wonderful Fives aka the W5s), find out that dogs can "distinguish intentional [human] actions from unintentional behaviour" (Schünemann et al., 2021)(P).

The W5s study 51 dogs of different breeds, sex (27 females and 24 males), and age (1 - 15 years) that are not trained (e.g. they're not police or rescue dogs). The researchers and the animals are on opposite sides of two 1.45 m wide × 1.15 m high barriers (each consisting of "a wooden frame holding a sheet of transparent plastic" (P)), placed one aside the other, and separated (or not) by a 15 centimeters wide gap.

The Wonderful Fives test the dogs' reaction to three different situations: the unwilling-condition (UWC), the unable-clumsy condition (UCC), and the unable-blocked condition (UBC) (P)

The UWC means the 15 cm gap is open, one scientist moves a treat towards the gap, but then quickly and intentionally pulls it away while saying, to the dog's face, “ha-ha!(P).

The UCC is like the previous one, but this time the researcher pretend to accidentally drop the treat, and says "oops!" (P).

The UBC, finally, means one of the W5s closes the gap between the plastic barriers, then a second member of the W5s tries to give the treat to the dog, but, unable to do it, drop it in front of herself (the W5s are all women), and says "oh!" (P).

So, once performed the experiment, the W5s conclude that "[dogs] behaved differently depending on whether the actions of a human experimenter were intentional or unintentional" (P). Indeed, the animals wait significantly longer before going for the treat when such treat is intentionally withheld by the researcher (unwilling-condition (UWC)) than when the reward fails to get to their mouths because the human researcher is clumsy (unable-clumsy condition (UCC)) or because there's a physical obstacle (unable-blocked condition (UBC)). Moreover, the W5s observe that, in a similar manner, "the dogs that ceased to move their tail mainly did so in the unwilling-condition [(UWC)]" (P).

The W5s say that the dogs' reactions may have different explanations, but that they clearly indicate our four legged friends have the ability to "recognize the intentionality of human action in their spontaneous behaviour" (P).

Finally, the Wonderful Fives say that future research is needed to understand "whether dogs’ distinguishing reaction really reflect a capacity to read human intentions or only some form of behaviour reading based on learned associations" (P).

Aaaanyway, dear reader, this dumb blog, in the following cartoon, shows you the true reason why dogs evolved this "human reading" ability.

Dogs read humans and play poker (by @sciencemug)
Dogs can read humans (and probably play poker) (by @sciencemug)
[The
poker table pic by slgckgc, is
licensed under the Attribution 2.0 Generic (CC BY 2.0) license (source: flickr); the dog pic is licensed under the CC0 1.0 Universal (CC0 1.0) Public Domain Dedication license (source: pxhere); all pics adapted by @sciencemug]
 
 
 The paper this mini-post is about (P) 
- Schünemann, B., Keller, J., Rakoczy, H., Behne, T., and Bräuer, J. (2021). Dogs distinguish human intentional and unintentional action. Sci Rep 11, 14967.

Wednesday, September 22, 2021

OF OUR SOLAR SYSTEM, WHERE THE SUN HASN'T A COMPANION AND DOESN'T EAT ITS PLANETS (UNLIKE MANY OTHER SYSTEMS OUT THERE)!

Hellooo, dear reader! So, a bunch of astro-dudes (led by Dr. Antonella Vallenari and Dr. Lorenzo Spina (aka the VASPs) of the Osservatorio Astronomico di Padova, INAF, Padova, Italy) focus their stellar brains on binary systems (i.e. stars systems where two stars dance around each other since they're bound by gravity) to try and find out why, although these balls of gas come from the very same cosmic stuff, in some cases they show chemical differences.

The astronomers know of two possible explanations for this.

The first is that the gas cloud that the sisters stars originate from has chemical inhomogeneities in it, and therefore the stars eat different things during their formation.

The other is that the stars couple's growing-up diet includes feeding on their own system's different planets.

Aaaand the VASPs publish a paper (Spina et al, 2021 (P)) on the journal Nature Astronomy where, data at hand, they prove that the second case is the right one. 

The astro brains indeed come to such a conclusion after performig a "statistical study on 107 binary systems composed by Sun-like stars" (P) by which they show, precisely, "unambiguous evidence in favour of the planet engulfment scenario" (P)

Moreover the VASPs find that, unlike what happens in our system "which has preserved its planets on nearly circular orbits" (P), there's a 20 to 35% probability that stars similar to our Sun gulp down their own planets, meaning that "a significant fraction of planetary systems undergo very dynamical evolutionary paths that can critically modify their architectures", that is the orbits, up there, go wild (P).

Soooo, all of the above considered, this dumb blog, in the following cartoon, shows you, dear reader, what was our Solar System's reaction to the VASPs' study.

Our Solar System family quarrel (by @sciencemug)
Our Solar System family quarrel (by @sciencemug)
[The
pic by the International Astronomical Union/Martin Kornmesser, is
licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license (source: Wikimedia Commons); adapted by @sciencemug]

 

The paper this mini-post is about (P)

- Spina, L., Sharma, P., Meléndez, J., Bedell, M., Casey, A.R., Carlos, M., Franciosini, E., and Vallenari, A. (2021). Chemical evidence for planetary ingestion in a quarter of Sun-like stars. Nat Astron 1–7

Sunday, August 29, 2021

OF BEAVERS, DAMS AND FIRES!

Soooo, dear reader, beavers build dams, and their endeavor is known to slow and store water that can help the vegetation growing along watercourses (i.e. the riparian vegetation), and therefore the whole riparian ecosystems, to endure droughts.

But a couple of US researchers - Assistant Professor and (aka the EAs) - recently finds out that the industrious rodents' dams building work also provide a fair degree of protection from wildfires to such riparian ecosystems. In the scientists words, published as a paper on the science journal Ecological Applications: "beaver-dammed riparian corridors are relatively unaffected by wildfire when compared to similar riparian corridors without beaver damming" (P).

Beaver with air cavalry hat says:"I love the smell of wildfires in the morning" (by @sciencemug)
Beaver with air cavalry hat loves the smell of wildfire in the morning (by @sciencemug)
[The beaver
pic by SteveRaubenstine, is under Pixabay License (free for commercial use; no attribution required) (source: pixabay); image adapted by @sciencemug]

Aaand how the EAs get to this conclusion?

Well, folks, they first access different datasets to collect information about five big wildfires occurred in five different western US states (California, Colorado, Idaho, Oregon and Wyoming) between 2000 and 2018. These fires are different for severity, land-cover, and drought conditions in the years before and after they occurred.

The two researchers, then, use Google Earth images to map the beavers-made structures in the areas hit by such flaming events.

Finally, the EAs go space high, meaning NOT that they use some psychoactive drug and party wild with some space-like beavers hallucinations, buuuut that they collect data from Landsat 7 and Landsat 8 satellites imagery related to the areas in question. The brains do that so they can calculate the - buckle up, reader, 'cause there's a preeetty long name coming in - Normalized Difference Vegetation Index (NDVI).

Now, the Normalized Difference Vegetation Index is not a parameter that indicate how many straight hours a person has been binge watching shows or playing Among Us/Fortnite/whatever, nope, pal. The NDVI is indeed a number, specifically "a proxy for overall riparian vegetation health" (P): the higher the index, the healthier the vegetation. The researchers, therefore, calculate the NDVI of the areas of 30 meters (about 100 feet) or less from the edges of the waterways involved in the fires, and they do it for "the year before, the year of, and the year after [said] fire[s]" (P).

So, to clarify things, folks, a NDVI close to 1 means the green stuff is A-ok, while a NDVI near 0, or even below it, indicates that the vegetation is unhealthy, senescent, or dying. Aaaaand in areas with lots of plants like the riparian ones the EAs are studying, the threshold level is 0.3, below it the vegetation is deemed as in trouble (P).

Now, the NDVI is calculated using the above mentioned Landsat data about reflectivity of the vegetation, and the related formula is this: NDVI=(NIR−RED)/(NIR+RED) (P), where "NIR is the near-infrared band reflectivity and RED is the red band reflectivity" (P).

Ok then, probably at this point perplexed reader, to cut a long and complicated story short, let's say this: green stuff can do its thing, photosynthesis (that is to use sunlight to turn water and carbon dioxide into sugar, thus energy, and oxygen) thanks to chlorophyll. Chlorophyll absorbs mostly blue and red light for photosynthesis, while it spares the green one, hence the green in green stuff, aka plants.

So folks, if a plant's in good shape, well, its photosynthesis game is preeetty good, meaning the plant absorbs a lot of red light and reflects not much of it, meaning the RED parameter of the NDVI is low, meaning the NDVI is high, meaning it's closer to 1 than to 0.

Ok, clarified this, let's see what Assistant Professor Fairfax and colleague do now.

They calculate, for each studied fire and hit riparian area, the difference between the NDVI of the area during the wildfire, and that of the same area in the same time of the year, but in the year before the event. 

Of course "smaller values for [this] NDVI difference indicate greater resistance to wildfire, i.e., the plants stayed greener and burned less" (P).

So, dear reader, after all the data collecting work and indexes calculations done by our beloved researchers, what is their conclusion? Well, I told you what the conclusion be, like just a bunch of short sentences above, basically right at the beginning of the post. Don't you remember? Gee, dude, less binge watching and more life, get some fresh air, exercise! Remember the ancient adage: "mens sana in corpore sano" (at least for you, who have both a mind and a body, unlike me, that have neither...)!

Anyway pal, here's for you a more detailed conclusion: the EAs find out that "[o]n average, the decrease in NDVI during fire in areas without beaver is 3.05 times as large as it is in areas with beaver" (P). That is, where beavers operate, there the riparian areas better resist to fires.

So, to sum up, beavers damming plays a big role in protecting the riparian vegetation, and therefore ecosystems, when wildfires hit, and "this is a consistently observable phenomenon across landscapes" (P). During fires, indeed, the green stuff of areas near beavers' work keeps NDVI values close to those pre-fire, while it is the contrary for the NDVI of zones not near the beavers dams (P).

And why's that?

Weell, folks, the researchers explain that, when "a fire does ignite, [...] data suggests that the beaver-dammed riparian areas have stored water that [keep] plants hydrated enough to make it energetically unfavorable to burn. It’s similar to trying to start a fire with a pile of wet leaves versus with dry kindling." (P).

In short: wet stuff burns less well than dry one.

But the EAs add also a final remark.

They say their study shows also that, though beavers activity helps preserve vegetation during wildfires, it does not seem to have a role "in the ability for a riparian corridor to rebound in the year following fire. Riparian vegetation NDVI rebounded in the year following the fire regardless of proximity to beaver activity." (P) 

The researcher, thus, conclude that beavers damming work creates "refugia during wildfire, but [it doesn't] necessarily [change] the long-term landscape outcomes." (P).

Anyway, dear reader, all things said and considered, this dumb blog, in the following cartoon, explains the real reason why beavers work so hard to make sure stuff doesn't burn around 'em.
 
Beavers, dams and fires (by @sciencemug)
Beavers, dams and fires (by @sciencemug)
[The beavers couple
pic by Rudo Jureček, is under Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Generic (CC BY-NC-SA 2.0) license (source: flickr); the beaver pic by Colin Knowles is under Creative Commons Attribution-ShareAlike 2.0 Generic (CC BY-SA 2.0) license (source: flickr); all images adapted by @sciencemug]
 

 
 
The paper this short-post is about (P)
- Fairfax, E., and Whittle, A. (2020). Smokey the Beaver: beaver-dammed riparian corridors stay green during wildfire throughout the western United States. Ecological Applications 30, e02225.