Longer Stay in Space Shrinks Human Heart - Study, AHA Journal

(Al Quran 6:125) …and whom He wills to go astray, He makes his heart narrow, much too narrow, as though he climbs up to the sky. In this way, Allah brings ignominy over those who do not believe.

Recent studies show evidence that human heart shrinks while in space and the health can sustain itself only for a year and then begins to deteriorate. The findings suggest that long-term weightlessness alters the structure of the heart, causing shrinkage and atrophy. The study published in American Heart Association's Circulation Journal, measured NASA astronaut Scott Kelly's heart before and during his 340-day time in space. It reported a loss of mass and initial drop in diameter in the left ventricles of the heart during the experience.[1] Other health changes reported were DNA damage, gene expression changes, a thickening of the retina, shifts in gut microbes, reduced cognitive abilities and a structural change at the ends of chromosomes called telomeres.[2] Its mainly due to to the long period of weightlessness experienced by astronauts including exposure to space radiation and other factors. The gravity experienced on Earth is what helps the heart to maintain both its size and function as it keeps blood pumping through our veins. The study suggests that astronauts engaged in long duration spaceflights suffer from atrial fibrillation, a form of arrhythmia, fast, irregular heartbeat about a decade earlier than the rest of the population and they could be at risk of developing this during such spaceflights. Atrial fibrillation can cause discomfort, reduce exercise tolerance and increase the risk of stroke in people who are otherwise healthy. While this may be an interesting piece of evidence for researchers it should also amaze Muslims to whom the Quran mentions the same:

(Al Quran 6:125) So, whom Allah wills to give guidance, He opens his heart for Islam (yashrah sadrahu lil-lslam), and whom He wills to go astray, He makes his heart narrow, much too narrow (yaj'al sadrahu dhaeeqan harajan), as though he climbs up to the sky. In this way, Allah brings ignominy over those who do not believe.

​The term sadr (صَدْر) used in the verse means "breast, or chest", also includes reference to our hearts. The term shrah sadr means removing of hindrance and distraction from the heart towards accepting something. In the verse it refers to Islam's universal teachings and principles, morals and ethics and all that is instructed to us becomes acceptable to our hearts without any doubts whatsoever. By comparing contentment and satisfaction of the heart to the physical shrinkage of the organ experienced by those who remain suspended in the air without gravity, like space travel, the Quran explains how Islam carries importance to one's life. Just as a healthy heart is the key to our health and wellbeing, the hearts acceptance of Islam is the key to its guidance and peace necessary for a righteous life and strength to face challenges with trust in Allah ﷻ. It is this certainty of Islamic faith and our complete submission to it that gives contentment to the heart and gives peace to our life. At the same time this is also Quran's wakeup call to atheists, agnostics & scientologists (followers of scientology religion) whose ranks fill the modern secular academia, including astronauts & astrophysicists: "In this way, Allah brings ignominy over those who do not believe." It is they who study the creation, day and night yet refuse to believe in the One Who Created it, the entire creation, which is a self evident phenomena of His Will and Existence. The ignominy they face is their inability to stop the impact of natural forces on their heart and health. 

Its important to note that during Isra Wa'al Mi'raj (Night Journey & Ascension) Prophet Muhammad ﷺ underwent a sort of a surgical operation and his blessed chest was cut open and his heart was prepared and strengthened in a way so that his blessed body may endure the extreme harshness of the space environment and not perish: "A golden tray full of wisdom and belief was brought to me and my body was cut open from the throat to the lower part of the Abdomen and then my Abdomen was washed with Zamzam water and (my heart was) filled with wisdom and belief...When I reached the nearest heaven. Gabriel said to the heaven gate-keeper, 'Open the gate.' ."[3] His blessed heart was filled with abstract notions such as "wisdom" and "faith" by Archangel Jibraeel (Gabriel) (alaihi salaam) before the commencing of his heavenly journey. Zam Zam, a water that carries miraculous properties and continues to abundantly flow till today in Makkah, was used in the process. The miraculous incident happened in Makkah at the time when Prophet ﷺ and his followers were experiencing the most difficult time of his prophethood. They faced severe persecution, hunger and basic necessities were cut off due to the social and economic boycott by Quraysh. This was in addition to unbearable loss of his most important political and emotional support, his uncle Abu Talib and his wife Khadija (r.a). It was in Makkah that the following verses of the Quran were revealed: (Al Quran 94:1-4) HAVE WE NOT opened up your heart, and lifted from you the burden that had weighed so heavily on your back? And [have We not] raised you high in dignity? - The difficulties and stress endured while preaching in Makkah, in addition to worry for future of Islam, had taken a toll on him, his stress and sadness was unbearable. It was during this time that his heart was given the necessary peace and calmness that lifted the burden of difficulties and provided him support for space travel as well as endurance to fulfill the mission of remaining part of prophet hood.

References:

[1] This is how the human heart adapts to space, CNN, By Ashley Strickland, Updated 2:06 AM ET, Tue March 30, 2021, https://www.cnn.com/2021/03/29/world/heart-shrinkage-weightlessness-space-wellness-scn/index.html

[2] Human health can be ‘mostly sustained’ for a year in space, NASA Twins Study concludes, CNN, By Ashley Strickland, CNN Updated 4:35 PM EDT, Thu April 11, 2019, https://www.cnn.com/2019/04/11/health/nasa-kelly-twins-study-results/index.html

[3] Sahih Al Bukhari Vol. 4, Book 54, Hadith 429 - Sunnah.com