Moja ya mambo mazuri kuhusu mama Ardhi ni uwepo wa anga. Uhai Duniani haungewezekana bila karatasi ya hewa hai ambayo inakumbatia kabisa Dunia kutoka pande zote. Katika awamu ya awali ya mabadiliko ya angahewa katika nyakati za kijiolojia, athari za kemikali ndani ya ukoko wa Dunia zilikuwa chanzo muhimu cha gesi. Hata hivyo, pamoja na mageuzi ya maisha, michakato ya biochemical inayohusishwa na maisha ilichukua na kudumisha usawa wa sasa wa gesi. Shukrani kwa mtiririko wa metali zilizoyeyuka katika mambo ya ndani ya Dunia ambayo huzaa uga wa sumaku wa Dunia unaohusika na kukengeusha sehemu kubwa ya upepo wa jua unaozaa (mkondo unaoendelea wa chembe zinazochajiwa na umeme yaani plasma inayotoka kwenye angahewa ya jua) mbali na Dunia. Safu ya juu kabisa ya angahewa inachukua mionzi ya ionizing iliyobaki, na kuwa ionised (kwa hivyo inaitwa ionosphere).
Je, Mwezi, satelaiti ya asili ya Dunia, ina angahewa?
The Moon does not have an atmosphere the way we experience it on Earth. Its gravitational field is weaker than Earth’s; while escape velocity at Earth’s surface is about 11.2 km/sec (air resistance disregarded), on Moon’s surface it is merely 2.4 km/sec which is much less than the root mean square (RMS) velocity of hydrogen molecules on the Moon. As a result, most of the hydrogen molecules escape to nafasi and the Moon is unable to retain any significant sheet of gases around it. However, this does not mean the Moon has no atmosphere at all. The Moon has an atmosphere but it’s so thin that a near vacuum condition prevails at the Moon’s surface. The Moon’s atmosphere is extremely thin: about 10 trillion times thinner than the Earth’s atmosphere. Density of the Moon’s atmosphere is at par with the density of the outermost fringes of Earth’s atmosphere1. Ni katika muktadha huu ambapo wengi wanasema kuwa Mwezi hauna angahewa.
The mwandamo anga ni muhimu kwa mustakabali wa mwanadamu. Kwa hivyo kumekuwa na mfululizo wa tafiti zaidi ya miaka 75 iliyopita.
NASA’s Appolo Mission made significant contributions when it first detected mwandamo anga4. Lunar Atmospheric Composition Experiment (LACE) of Apollo 17 found small amounts of a number of atoms and molecules (including helium, argon, and possibly neon, ammonia, methane and carbon dioxide) on the Moon’s surface1. Baadaye, vipimo vya msingi vya ardhi viligundua mvuke wa sodiamu na potasiamu katika angahewa la Mwezi kwa kutumia uchunguzi wa mstari wa uzalishaji.2. There were also reports on the finding of metal ions emanating from the Moon in interplanetary nafasi na H2O barafu kwenye eneo la polar la Mwezi3.
Kwa Ga 3 zilizopita (1 Ga au giga-mwaka = miaka bilioni 1 au 109 miaka), angahewa ya Mwezi ni thabiti na exosphere ya mipaka ya uso wa chini-wiani (SBE). Kabla ya hapo, Mwezi ulikuwa na angahewa mashuhuri zaidi, ingawa ni ya muda mfupi kutokana na shughuli nyingi za volkano kwenye Mwezi.4.
Masomo yaliyochapishwa hivi majuzi kwa kutumia vipimo kutoka ISRO’s lunar orbiter reveal that the ionosphere of the Moon can have a very high electron density. The mwandamo surface electron density could be as high as 1.2 × 105 per cubic cm but the solar wind acts as a strong removal agent sweeping all the plasma to the interplanetary kati5. Ugunduzi wa kuvutia hata hivyo ulikuwa uchunguzi wa maudhui ya juu ya elektroni katika eneo la wake (eneo la misukosuko inayofuata katika upepo wa jua katika mwelekeo wa kuzuia jua). Ilikuwa kubwa kuliko mwelekeo wa mchana kutokana na ukweli kwamba hakuna mionzi ya jua au upepo wa jua huingiliana moja kwa moja na chembe za upande wowote zinazopatikana katika eneo hili.6. Utafiti unaonyesha kwamba ioni zinazotawala katika eneo la wake ni Ar+, na Ne+ ambazo zina muda mrefu zaidi wa maisha kuliko ioni za molekuli (CO2+, na H2O+ ) ambazo zinatawala katika mikoa mingine. Kwa sababu ya maisha yao ya juu, Ar+ na Ne+ ions survive in the wake region while the molecular ions recombine and disappear. High electron density was found also near mwandamo polar regions during solar transition periods5,6.
NASA planned Artemis Mission to the Moon aims to set up Artemis Base Camp on the mwandamo surface and the Gateway in mwandamo obiti. This will certainly help more detailed and direct study of the mwandamo anga7.
***
Marejeo:
- NASA 2013. Je, Kuna Anga Juu ya Mwezi? Inapatikana mtandaoni kwa https://www.nasa.gov/mission_pages/LADEE/news/lunar-atmosphere.html#:~:text=Just%20as%20the%20discovery%20of,of%20Earth%2C%20Mars%20or%20Venus.
- Potter AE na Morgan TH 1988. Ugunduzi wa Mvuke wa Sodiamu na Potasiamu katika Anga ya Mwezi. SAYANSI 5 Ago 1988 Vol 241, Toleo la 4866 uk. 675-680. DOI: https://doi.org/10.1126/science.241.4866.67
- Stern SA 1999. Mazingira ya mwandamo: Historia, hadhi, matatizo ya sasa, na muktadha. Maoni ya Jiofizikia. Ilichapishwa kwa mara ya kwanza: 01 Novemba 1999. Juzuu 37, Toleo la 4 Novemba 1999. Kurasa 453-491. DOI: https://doi.org/10.1029/1999RG900005
- Needham DH na Kringab DA 2017. Volkano ya mwandamo ilitoa angahewa ya muda kuzunguka Mwezi wa kale. Barua za Sayansi ya Dunia na Sayari. Juzuu 478, 15 Novemba 2017, Kurasa 175-178. DOI: https://doi.org/10.1016/j.epsl.2017.09.002
- Ambili KM na Choudhary RK 2021. Usambazaji wa pande tatu wa ayoni na elektroni katika ionosfere ya mwezi ulitokana na athari za fotokemikali. Notisi za Kila Mwezi za Jumuiya ya Kifalme ya Astronomical, Juzuu 510, Toleo la 3, Machi 2022, Kurasa 3291–3300, DOI: https://doi.org/10.1093/mnras/stab3734
- Tripathi KR, et al 2022. A study on the characteristic features of the lunar ionosphere using dual frequency redio science (DFRS) experiment onboard Chandrayaan-2 orbiter. Monthly Notices of the Royal Astronomical Society: Letters, Volume 515, Issue 1, September 2022, Pages L61–L66, DOI: https://doi.org/10.1093/mnrasl/slac058
- NASA 2022. Misheni ya Artemis. Inapatikana kwa https://www.nasa.gov/specials/artemis/
***
