-
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?
-
- 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
-
- 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.
-
- One way to trigger this decomposition of
ammonia is by using copper nanoparticles decorated with clusters of ruthenium
atoms, which catalyze the reaction.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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.
-
- 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).
-
- 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.
-
- 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.
-
January 1, 2022 BATTERIES
and RADAR - minuturzation? 3817
----------------------------------------------------------------------------------------
-----
Comments appreciated and Pass it on to whomever is interested. ---
--- Some
reviews are at: -------------- http://jdetrick.blogspot.com -----
-- email
feedback, corrections, request for copies or Index of all reviews
---
to: ------ jamesdetrick@comcast.net ------
“Jim Detrick” -----------
--------------------- --- Tuesday, January 10, 2023 ---------------------------
-
No comments:
Post a Comment