화성의 물은 암석 깊은 곳에 갇혔다?

제2의 지구라고 일컬어지는 화성의 표면을 보면 지구의 표면에서 볼 수 있는 것과 거의 비슷한 암석들이 흩어져 있습니다.

 

크고 작은 암석이 있었다는 것은 과거에 물이 존재했었다는 것을 암시하는데 과학자들의 연구에 의하면, 화성에 40억 년 전에는 물과 바람이 있었다고 합니다.

 

지금의 화성 대기의 구성은 이산화탄소가 약 95%, 질소가 약 3%, 아르곤이 약 1.6%이고, 다른 미량의 산소와 수증기 등을 포함하고 있지만 오주 오랜 옛날에는 지구에서처럼 물이 흐르고 있었습니다.

 

화성의 대기는 겨울 몇 개월간 극지방에서 밤이 계속되면 지표는 매우 저온이 되고 대기 전체의 약 25%나 얼어버려서 대기압이 낮아집니다.

 

이후 극에 다시 햇빛이 비추는 계절이 되면 얼었던 이산화탄소가 승화하여 극지방에 강한 바람이 발생합니다.

 

화성의 표면온도는 약 -140°C~20°C 정도로 평균온도는 약 -80°C인데 이렇게 낮은 온도는 화성의 대기가 희박하기 때문에 열을 유지할 수 없기 때문이라 알려져 있습니다. 

 

그런데 화성에 그 많던 물이 어떻게 대기 중으로 흩어졌는지 궁금했는데 화성의 자기 보호막은 약해서 물의 원소 성분이 행성에서 빠져나오도록 했을 수도 있고 합니다.

그러나 컴퓨터 시물레이션을 통하여 화성의 초기 물의 30~99%가 광물에 통합되어 화성의 지각에 묻혔다는 것을 연구가 있는데 상당히 흥미로운 대목입니다.

 

이에 cnn이 보도한 기사를 번역하여 소개합니다.

 

화성: 행성에 엄청난 양의 물이 잠겼을지도 모른다.

Mars: Vast amount of water may be locked up on planet

 

 

 

이것은 오랜 미스테리이다.: 어떻게 화성이 수십억 년 전에 표면을 가로질러 흐르던 물을 잃었는가 하는 것은.
과학자들은 이제 해답을 가지고 있다고 생각한다: 대부분의 해답은 지구의 외층인 지각에 갇히게 되었다.
고대의 물은 화성암에 함유된 광물의 형태로 존재한다.

It's a longstanding mystery: how Mars lost the water that flowed across its surface billions of years ago.

Scientists now think they have an answer: much of it became trapped in the planet's outer layer - its crust.

The ancient water exists in the form of minerals contained within Martian rocks.

 

이 연구결과는 제52회 달과 행성 과학 컨퍼런스에서 논의되었으며 사이언스 저널에 실렸다.
이 연구는 화성 궤도를 도는 우주선, 탐사선, 운석으로부터 수집한 측정값을 사용했다.
그리고 나서 연구원들은 시간이 지남에 따라 행성에서 물이 어떻게 손실되었는지 컴퓨터 시뮬레이션을 개발했다.
40억 년 전만 해도 화성은 더 따뜻하고 습했다. 아마도 더 두꺼운 대기를 가지고 있었을 것이다. 물은 강을 통해 흐르고, 암석의 수로를 끊고, 충돌구 속에 고여 있었다.

The findings have been discussed at the 52nd Lunar and Planetary Science Conference and are published in Science journal.

The study used measurements gathered from Mars-orbiting spacecraft, rovers and meteorites.

Researchers then developed a computer simulation of how water was lost from the planet over time.

More than four billion years ago, Mars was warmer and wetter - possibly with a thicker atmosphere. Water coursed through rivers, cutting channels in the rock, and pooled in impact craters.

* meteorite: 운석

레드 플래닛은 100미터에서 1킬로미터 깊이의 층으로 전체 표면을 덮을 만큼 충분한 물을 수용할 수 있었을 것이다.
약 10억년 후, 화성은 오늘날 우리가 인식하고 있는 더 춥고 황량한 행성으로 변모했다.
"우리는 오랫동안 화성이 초기 역사에서 훨씬 더 젖었다는 것을 알고 있었다. 그러나 이 물의 정확한 운명은 현재 진행 중인 문제였다," 라고 이번 연구에 참여하지 않은 행성 과학자 피터 그린로드 박사가 말했다.
런던 자연사 박물관의 그린로드 박사는 BBC 뉴스에 "우리는 이미 화성 대기에 대한 연구를 통해 그 중 일부가 우주로 날아가 버렸다는 것을 알고 있으며, 표면과 바로 아래에 쌓인 얼음 퇴적물은 우리에게 어떤 물이 얼게 되었다는 것을 말해준다"고 말했다.

The Red Planet could have held enough water to cover its entire surface in a layer measuring between 100m and one kilometre deep.

Around a billion years later, Mars had made the transition to the colder, desolate planet we recognise today.

"We have known for a long time that Mars was much wetter in its early history. But, the exact fate of that water has been an ongoing problem," said planetary scientist Dr Peter Grindrod, who was not involved with the latest study.

Dr Grindrod, from London's Natural History Museum, told BBC News: "We already know from studies of the atmosphere of Mars that some of that water was lost to space, and ice deposits on and just below the surface tell us that some water became frozen."

지구는 대기가 빠져나가는 것을 막는 자석 보호막, 즉 자기권을 가지고 있다. 하지만 화성의 자기 보호막은 약해서 물의 원소 성분이 행성에서 빠져나오도록 했을 수도 있다.
그러나 오늘날 수소의 화학 성분 중 하나인 수소가 대기로부터 빠져나가는 속도는 이 메커니즘이 수소가 어디로 갔는지 설명할 수 없다는 것을 암시합니다.
패서디나에 있는 캘리포니아 공과대학(Caltech)의 에바 린한 셸러와 동료들은 이제 그들이 답을 생각해냈다고 생각한다.
Earth has a magnetic shield, or magnetosphere, that helps prevent the atmosphere from escaping. But Mars' magnetic shield is weak and could have allowed elemental components of water to escape from the planet.

But the rate at which hydrogen - one chemical constituent of water - escapes from that atmosphere today suggests this mechanism can't explain where all of it went. 

Eva Linghan Scheller and colleagues from the California Institute of Technology (Caltech) in Pasadena now think they have come up with the answer.

* magnetosphere: 자기권

 

 

Nasa의 최신 탐사선은 흐르는 물이 있는 곳에 위치한 델타라고 불리는 지질학적 특징을 탐험할 것이다.
그들의 컴퓨터 모델링 작업의 결과는 화성의 초기 물의 30~99%가 광물에 통합되어 화성의 지각에 묻혔다는 것을 보여준다.
공동 저자인 칼텍 출신의 베다니 엘만 교수는 "화성 탐사 데이터를 연구함으로써, 물이 변했다는 증거를 찾는 것이 흔하고 드물지 않은 일이라는 것이 분명해졌다"고 설명했다.

Nasa's latest rover will explore a geological feature called a delta, laid down in the presence of flowing water

The results of their computer modelling work show that between 30% and 99% of Mars' initial water was incorporated into minerals and buried in the planet's crust.

Co-author Prof Bethany Ehlmann, also from from Caltech, explained that, "by studying data from Mars missions, It became clear that it was common - and not rare - to find evidence of water alteration". 

그녀는 이어 "껍질이 변형되면 액체 상태의 물과 같은 물을 가져다가 수분을 함유한 미네랄에 가둬 효과적으로 갇히게 된다"고 덧붙였다.
저자들은 대부분의 물이 약 41억년에서 37억 년 전 사이 - 노아치안 시대로 알려진 화성 역사 기간 동안 유실되었다고 제안한다.

She continued: "When the crust becomes altered, it takes water - like liquid water - and sequesters it in a hydrated mineral that has water in its structure so that it is effectively trapped."

The authors suggest that most of the water was lost between about 4.1 and 3.7 billion years ago - during a stretch of Martian history known as the Noachian Period. 

 

나사의 화성 탐사 프로그램의 수석 과학자인 마이클 마이어 박사는 "화성 탐사가 행성의 지질학, 기후, 생명에 있어서 중심적인 역할을 하기 때문에 화성 탐사의 원래 중요한 역할은 물을 따라가는 것이었다"고 말했다.
"이것은 화성에 얼마나 많은 물이 있었는지, 어떻게 그것이 손실되었을지, 그리고 그것이 오늘날 어디에 있을지를 이해하는 데 매우 중요한 논문입니다."
Grindrod 박사는 "이 새로운 연구가 우리에게 말해주는 것은 많은 양의 물, 아마도 대다수는 화성의 바위에 갇혀있을 수 있다는 것입니다. 이 수분 공급 과정은 수심 1km의 전지구적 층에 해당하는 양의 물을 저장할 수 있습니다."

Dr Michael Meyer, lead scientist for Nasa's Mars exploration program, said: "The original overarching role of Mars exploration has been to follow the water, since it plays such a central role in the geology, climate and life of the planet.

"This is a very important paper to understand how much water was on Mars, how it might have been lost and where it might be today."

Dr Grindrod added: "What this new study tells us is that a lot of that water, possibly the majority, could have actually been locked into the rocks on Mars. This process of hydration is capable of storing large volumes of water, up to an amount equivalent to a global layer a kilometre deep."

"화성이 형성된 지 약 10억 5천만 년이 지난 후 액체 상태의 물이 대부분 사라졌지만, 오늘날 우리는 인버턴스 탐사선이 탐사하고 있는 제로의 분화구 같은 곳에서 수분이 함유된 광물의 증거를 볼 수 있습니다.
"화성의 초기 기후는 행성 과학에서 가장 중요한 주제 중 하나로 남아 있으며, 이 연구는 물 손실의 원인이 되는 과정을 이해하는 데 도움이 될 것입니다."

"Although most of the liquid water had probably disappeared after about one and a half billion years after Mars formed, we see evidence of hydrated minerals at the surface today, in areas like Jezero Crater, which is currently being explored by the Perseverance rover.

"The early climate of Mars remains one of the most important topics in planetary science, and this study will help our understanding of the processes responsible for water loss."

 

 

 

 

* 기사 내용 및 사진 출처: cnn