Tuesday, January 10, 2023

3817 - BATTERIES and RADAR - miniaturization is key?

 

     -  3817  -    BATTERIES and RADAR  -  miniaturization is key?    CubeSats and miniaturized instruments are likely to become more ubiquitous on deep space missions. While these compact space probes are less well-rounded than their larger counterparts, they offer specialized capabilities at a relatively low cost, making them an ideal supplement to the larger mission.

           


            ---------  3817  -  BATTERIES and RADAR  -  miniaturization is key?

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            -   Batteries could use ammonia.  Ammonia could be the key to storing hydrogen fuel.  For decades, the possibility of using hydrogen as a carbon-free fuel has remained a captivating concept. But the need to store it at extreme pressures and ultra-cold temperatures has been an ever-present barrier to its more widespread rollout.  However, new experiments produce hydrogen with LEDs

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            -   One possible solution is to use liquid ammonia (NH3) to store the hydrogen atoms, and then break the compound down when you need to extract the hydrogen for fuel. Ammonia is much easier to store and transport, but extracting hydrogen from it is tricky.

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            -    One way to trigger this decomposition of ammonia is by using copper nanoparticles decorated with clusters of ruthenium atoms, which catalyze the reaction.

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            -    When these nanoparticles are illuminated with ultra-fast laser pulses, the effect can excite the electrons on their surfaces, leaving behind positively-charged holes. Together, these electron-hole pairs will readily react with molecules like ammonia. This process ultimately releases pure hydrogen, leaving the catalyzing nanoparticles unchanged for the next reaction.

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            -    Ammonia is much easier to store and transport, but extracting hydrogen from it is tricky.  Despite the benefits of this technique, the ruthenium photocatalysts best suited for the process are both rare and expensive, making it especially difficult to recreate the process on industrial scales.

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            -    Alternatively, ammonia can be broken down by replacing ruthenium with “transition” metals like iron, which are cheaper and more abundant.  Compared with elements like ruthenium, which lies in the platinum group of metals, transition metals form far stronger bonds with the intermediate products during the breakdown of ammonia, preventing the reaction from progressing further.

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            -    To spark the reaction, transition metal photocatalysts must instead be heated to temperatures exceeding 400 degrees. This ultimately makes the process both similarly costly, and far more energy-intensive, than just using ruthenium.

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            -    LEDs and quantum simulations found a way around this challenge. Instead of heating transition metals, the team illuminated them with a bright, finely-tuned LED.

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            -    The iron’s performance remained on par with far more expensive ruthenium-coated nanoparticles.  To optimize the frequency and intensity of this light, they used virtual experiments.   They probed the molecular-scale interactions taking place between the LED’s light, and the electron-hole pairs which formed on the nanoparticle surfaces.

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            -    With the ability to predict these deeply complex reactions they could construct an optimal setup for transforming LED light into chemical energy. They illuminated copper nanoparticles, adorned with clusters of iron atoms, then measured the amount of pure hydrogen they could extract from liquid ammonia.

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            -    After six hours, the iron’s performance remained on par with far more expensive ruthenium-coated nanoparticles, both without the need for high temperatures, and with a similar concentration of metallic atoms.

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            -    One of the biggest remaining barriers is the need to improve on existing methods for ammonia production in the first place. This is an energy-intensive process, where fossil fuels must be subjected to high temperatures and pressures.

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            -    Once produced, however, liquid ammonia can be easily stored and transported at room temperatures and pressures, offering a far more realistic alternative to storing hydrogen fuel directly. There are efforts underway to produce ammonia from green hydrogen made with solar energy, rather than the current process that relies on natural gas.

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            -    On top of this, LEDs are already highly effective at converting electrical energy into light, and improvements to this efficiency are only expected to skyrocket further in the coming years. In turn, LED light could be produced in increasing abundance by renewable energy sources, presenting a promising route forward in the fight against climate change.

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            -  On the innovations of radars space exploration is motivating miniaturization.  The smallest radar ever sent to space will probe the interior of Dimorphos after its impact from DART

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            -   While school bus-sized flagship missions still zoom around our solar system from Mars to Jupiter, they are more and more frequently accompanied by tiny tag-along CubeSats with specialized capabilities.

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            -   That trend is set to continue in 2024 when the European Space Agency (ESA)’s “Juventas CubeSat” blasts off on its way to asteroid Dimorphos: the site of September’s dramatic impact event, where NASA’s DART mission purposely crashed a spacecraft at high speeds to test the viability of asteroid redirection by humans.

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            -  The Juventas CubeSat is equipped with a radar instrument, the smallest ever sent to space, to probe beneath the asteroid’s surface and understand its structure in the aftermath of the impact.

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            -    Juventas is one of three ESA probes that will fly to Dimorphos together. A second CubeSat, “Milani”, is designed to study the composition of the asteroid’s surface and dust. Meanwhile, a larger probe, named Hera, will complete the trio with a more comprehensive suite of instruments. Together, they will offer a complete survey of Dimorphos, its internal and surface features, its mass, and, importantly, the size and characteristics of the crater left by DART.-

            -    Dimorphos is a ‘moon’ orbiting a larger asteroid named Didymos, and before the impact, each orbit took 11 hours and 55 minutes. NASA scientists hoped to demonstrate a change in the orbital period of at least 73 seconds to consider the mission a success. That mark was wildly surpassed, shortening Dimorphos’ orbit by an astounding 32 minutes.

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            -    When it comes to planetary defense, even a small change to an asteroid’s trajectory can prevent a catastrophic impact, as long as it is done early enough, so the DART mission’s results are exciting. While Dimorphos is only a very small asteroid (170 meters across), and larger objects will be harder to deflect, DART’s ability to significantly change Dimorphos’ orbit offers a reassuring proof of concept.

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            -   Should the Universe happen to send a dangerous object hurtling our way, Earth will be ready, provided we see it coming in time.  It may be comforting to know that most large asteroids in the solar system are tracked by space agencies around the world, so the chance of a surprise asteroid impact is low.

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            -    In fact, the more likely threat may come not from asteroids but from comets, which spend most of their time out in the Kuiper Belt beyond Neptune, making them nearly impossible to track and predict.  We know quite a lot about cometary structures, through missions such as the Rosetta probe that visited comet 67P/Churyumov-Gerasimenko back in 2014.

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            -    The Juventas CubeSat’s tiny radar instrument being sent to Dimorphos will be a miniaturized version of the one Rosetta carried to comet 67P.   When Juventas, Milani, and Hera arrive at Dimorphos in 2026, they will get up close and personal with it, offering detailed information about the asteroid’s composition.

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            -    Asteroids that are solid may deflect differently than asteroids made up of small gravel and boulders, so learning as much as possible about the object’s composition can only improve our understanding of the physics involved in redirect missions, should one ever become necessary. And CubeSats like Juventas are capable tools for this kind of investigative mission.

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            -    Since the first deep space CubeSats flew in 2018 (the twin MarCO spacecraft that accompanied InSight on its way to Mars), dozens more mini probes have been planned and built. Some have already proven their worth.

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            -    JAXA’s Hayabusa 2 mission to asteroid Ryugu landed three tiny rovers (the twin Minerva-II rovers and the German-built MASCOT rover) on the asteroid’s surface in late 2018, and a deployable camera was released from the spacecraft to observe an impact event (when Hayabusa 2 ‘shot’ the asteroid to expose the subsurface for sampling).

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            -   The upcoming “Europa Clipper” is expected to carry CubeSats too, as is the imminent Artemis 1 mission to the Moon. The CAPSTONE CubeSat is already in Lunar orbit right now, testing capabilities that will be required for Artemis’ Gateway space station.

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            -  Across the solar system, CubeSats are making waves. They say big things come in small packages, and when it comes to space exploration, that may yet prove to be truer than we imagined.

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            January 1, 2022     BATTERIES and RADAR  -  minuturzation?   3817                                                                                                                               

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            --------------------- ---  Tuesday, January 10, 2023  ---------------------------

             

             

             

             

                     

             

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