Can you make it out with a “chin in the microwave”? It turns out that water can be obtained efficiently from moon sand | sorae portal site to space

Several issues related to the long-term stay on the moon planned for the future were noted. One of the main issuesSecuring large amounts of water on the moonHe is. This is because transporting water from the earth, which is used to support human life, is very expensive.

Fortunately, recent studies have shown that there is an abundance of water on the surface of the Moon. It is also known that most of the water is inside craters near the poles of the Moon. The interior of the polar crater is permanently blocked from sunlight.permanent shadowThere is a place where there is permanent shadow water in the form of very fine, frost-like ice crystals, which are thought to be about 1/20 the size as regolith (the sandy material that covers the surface of the moon).

However, it is notoriously difficult to melt ice mixed with sand and extract it as water. Sunlight and lasers were devised as heat sources for melting ice, but neither is suitable for heating. This is due to a material composition problem that “ice is mostly occupied by regolith” and an anisotropy problem that “only the surface can be heated”.

Therefore, an alternative was proposedDielectric heating by microwaveHe is. In short, this is how you “microwave” moon sand. Although the action is weaker than liquid water, it is possible to heat regolith, which is rock, using microwaves. Microwaves that permeate the inside of the material can be used to heat it uniformly, so regolith can generate enough heat to melt the ice. Also, as you can see from the widespread use of microwave ovens, this method has the advantage of being easy to operate and more energy efficient than lasers.

In the past, imitations of regolith (artefacts with the same composition and grain shape as regolith) containing ice at a very small percentage of 1 wt% to 2 wt% (wt% = weight percentage) were heated by microwave irradiation. A research case that succeeded in extracting it. However, in this research, the problem was that the microwave output was very large, ranging from 1000 watts to 1200 watts. It is expected that a lunar base with limited resources would need to extract water using low-power microwaves, but it was not known whether low-power microwaves could extract water without problems.

للإجابة على هذا السؤال ، أجرى فريق بحث بقيادة جيمس دي كول من الجامعة المفتوحة تجربة. ما تم تحضيره هو فرن ميكروويف بقوة 250 وات ينتج أقل بكثير من فرن الميكروويف المنزلي النموذجي (الطول الموجي هو نفسه فرن الميكروويف المنزلي ، 2.45 جيجاهرتز).

أعد كول وزملاؤه نوعين من تقليد الثرى بتركيبات كيميائية مختلفة تم تحضيرهما بناءً على نتائج الملاحظة لسطح القمر ، وأعدوا عينات تحتوي على جليد بنسب مختلفة من 3.0٪ إلى 14.7٪ بالوزن ، على التوالي. من أجل مطابقة الظروف التجريبية ، قمنا بفحص كمية الماء التي يمكن استخلاصها بواسطة تشعيع الميكروويف لمدة 25 دقيقة.

【▲ الشكل 2: النتائج التجريبية مع نوعين من محاكاة الثرى (LHS-1 و LMS-1). تستخرج العينات التي تحتوي على معظم الجليد (الجانب الأيمن من الرسم البياني) كمية أقل من الماء مقارنة بالعينات التي تحتوي على كمية أقل من الجليد (مصدر الصورة: James D. Cole ، وآخرون)]

As a result, in most samples47% to 67% of moisture can be extracted by heating with a 250-watt microwave for 25 minutes.I understand. This ratio is more efficient than the laser heating performed in previous experiments. It was also found that if the irradiation continued, 88% of the water content could be removed in 35 minutes from a 6 wt% sample.

It was also shown that the difference in the chemical composition of the regolith mimics has little effect on the water recovery efficiency. However, unlike the actual lunar regolith, the simulated regolith used in the experiment does not contain any material that is easily heated by microwaves, so the actual material is expected to heat up and extract moisture more efficiently.

【▲ Figure 3: The regolith is heated by microwave radiation, and the heat melts the ice (top). In a regolith with a lot of ice (bottom), it is assumed that the ice in the part not in contact with the regolith melted and remained, resulting in poor water extraction[Credit: James D. Cole, et.al.]

On the other hand, it was also found that the samples with the highest percentage of ice were the least efficient in extracting water. This is presumably because too much ice fills the gaps in the regolith, leaving the ice that is not in contact with the regolith without melting. In addition, the dielectric heating of solid water is weaker than that of liquid water, and the ice itself does not generate heat, which causes the ice to remain unmelted.

The maximum percentage of ice tested in this experiment was 14.7 wt%, but regolith has also been found to contain abundant ice of more than 30 wt% in lunar surface observations. Dielectric heating using microwaves is not the only method for extracting moisture from regolith, other methods can be thought of.

However, the percentage of ice present in permanent shade is 5.6 wt%, which is well within the range shown in our experiments to be extracted efficiently, indicating that regolith with low ice content is abundant. Dielectric heating by microwaves could be the primary, if not the only, method for getting water on the Moon.

source

• James DeColl and others. “Water extraction from simulated lunar ice using low-energy microwave heating”. (acta space)

Text: Rare Aya