abcc词NASA计划2030年将⼈送上⽕星，那⽕星上的重⼒有多强？
⽕星与我们的地球有很多共同的特征。这两个⾏星都有⼤致相同的地表⾯积，都有极冠，都有类似的倾斜旋转轴，使得⽕星和地球都有很强的季节性变化。此外，有确凿证据显⽰，在过去，这两个⾏星曾经历过⽓候变化。
同时，这两个⾏星在很多重要的⽅⾯,⼜是完全不同的。例如,⽕星表⾯的平均⼤⽓压强仅为⼤约7.5毫巴(⽐地球上的1%还⼩)，地球上的⼤⽓压强超过1000毫巴。⽕星的平均表⾯温度也很低，达到零下63 °C,⽽地球上则是温和的14 °C。⽕星上⼀天的时长与地球相当,24⼩时37分钟，但⽕星上⼀年明显⽐地球长出很多，有687天。
两个⾏星之间最⼤的不同就是,⽕星表⾯的重⼒⽐地球上⼩得多——准确地说,⽐地球低62%。只有地球标准的0.38,⼀个在地球上重100公⽄的⼈，在⽕星上，他的体重就只有38公⽄了。
地表重⼒的差异源于很多因素的影响——质量，密度，半径(这是最重要的因素)。虽然⽕星的表⾯积相当于地球的陆地⾯积，但是它的直径只有地球的⼀半，密度也⼩于地球，只有地球体积的15%，地球质量的11%。
根据⽜顿的引⼒理论，科学家们计算了⽕星的重⼒，该理论认为⼀个物体所产⽣的引⼒与它的质量成正
教师教育⽐。将该理论应⽤到⾏星这类球体的时候(在本例中，指⽕星)，质量给定的时候，表⾯重⼒与它半径的平⽅成反⽐。密度给定的时候，重⼒与半径成正⽐。
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重⼒公式的表达式为g = m/ r2，其中g是⽕星表⾯重⼒(表⽰为地球表⾯重⼒的倍数，地球重⼒为9.8m/s2),m代表质量，表⽰为地球质量(5.976*1024kg)的倍数,r代表半径，表⽰为地球平均半径(6371km)的倍数。
例如,⽕星的质量是6.4185*1023kg，是地球质量的0.107倍。它的平均半径是3390km，是地球半径的0.532，因此,⽕星表⾯重⼒的计算公式，代⼊数字后为:0.107/0.5322=0.107/0.2830，计算得到的数值为0.38。根据地球表⾯重⼒，计算得出的加速度为3.724⽶每秒的平⽅。
五监如果我们想要将宇航员，探险家送上⽕星，或者有⼀天在⽕星定居，那么了解⽕星上的重⼒，及其对陆地⽣命的影响将是⾮常关键的⼀步。对于任何打算进⾏载⼈航天或殖民⽕星的计划，了解长期暴露于只有地球重⼒三分之⼀的环境下会造成哪些影响，是⼀个关键的⽅⾯。
例如，像⽕星1号这样的众包项⽬也考虑到了参与者肌⾁退化和⾻质酥松的可能性。引⽤了国际空间站宇航员的⼀项最新研究，他们承认，这个持续时间4-6个⽉的任务会导致肌⾁性能最⾼会达到30%的损失，肌⾁质量最⾼达到15%的损失。
他们提出的任务，不仅需要花费⼏个⽉的时间才能到达⽕星,⽽且要求志愿者的余⽣都要在⽕星上度过。他们还声称，他们计划降低这些数字，让宇航员们“准备好⼀个有效的对策⽅案，保证宇航员的健康，不仅仅安全到达⽕星，也会让宇航员适应⽕星表⾯的重⼒。”所有这些措施还有待观察。高育良扮演者
了解更多关于⽕星重⼒和陆地⽣物在这样的重⼒环境下如何⽣存，对于其它⾏星的太空探索和任务来说也⾮常重要。随着⽕星上的机器⼈着陆器、轨道任务，以及载⼈飞⾏任务所传回的科学信息，我们有望更详细地了解⽕星的重⼒。NASA提出的载⼈⽕星探测任务，计划于2030年发射，我们期待科学家们更多的研究成果。 (张微/编译)
以下为英⽂原⽂:
How strong is the gravity on Mars?
The planet Mars shares numerous characteristics with our own. Both planets have roughly the same amount of land surface area, sustained polar caps, and both have a similar tilt in their rotational axes, affording each of them strong asonal variability. Additionally, both planets prent strong evidence of having undergone climate change in the past.
一件令我感动的事作文At the same time, our two planets are really quite different, and in a number of important ways. For i
nstance, atmospheric pressure on Mars is only a fraction of what it is here on Earth – averaging 7.5 millibars on Mars to just over 1000 here on Earth. The average surface temperature is also lower on Mars, ranking in at a frigid -63 °C compared to Earth's balmy 14 °C. And while the length of a Martian day is roughly the same as it is here on Earth (24 hours 37 minutes), the length of a Martian year is significantly longer (687 days).
But one big difference is that the gravity on Mars' surface is much lower than it is here on Earth – 62% lower to be preci. At just 0.38 of the Earth standard, a person who weighs 100 kg on Earth would weigh only 38 kg on Mars. This difference in surface gravity is due to a number of factors – mass, density, and radius being the foremost. Even though Mars has almost the same land surface area as Earth, it has only half the diameter and less density than Earth – posssing roughly 15% of Earth's volume and 11% of its mass.
Scientists have calculated Mars' gravity bad on Newton's theory of gravity, which states that the gravitational force exerted by an object is proportional to its mass. When applied to a spherical body like a planet with a given mass (in this ca, Mars), the surface gravity will be approximately inverly proportional to the square of its radius. When applied to a spherical body with a given average density, it will be approximately proportional to its radius.
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The proportionalities can be expresd by the formula g = m/r2, where g is the surface gravity of Mars (expresd as
The proportionalities can be expresd by the formula g = m/r2, where g is the surface gravity of Mars (expresd as a multiple of the Earth's, which is 9.8 m/s2), m is its mass – expresd as a multiple of the Earth's mass (5.976·1024 kg) – and r its radius, expresd as a multiple of the Earth's (mean) radius (6,371 km).
For instance, Mars has a mass of 6.4185·1023 kg, which is 0.107 Earth mass. It also has a mean radius of 3,390 km, which works out to 0.532 Earth radii. The surface gravity of Mars can therefore be expresd mathematically as:
0.107/0.5322, from which we get the value of 0.38. Bad on the Earth's own surface gravity, this works out to an acceleration of 3.724 meters per cond2.
Understanding Mars' gravity and its affect on terrestrial beings is an important first step if we want to nd astronauts, explorers, and even ttlers there someday. Basically, the effects of long-term exposure to gravity that is just over one-third the Earth normal will be a key aspect of any plans for upcoming manned missions or colonization efforts.
For example, crowd-sourced projects like Mars One make allowances for the likelihood of muscle deterioration and osteoporosis for their participants. Citing a recent study of International Space Station (ISS) astronauts, they acknowledge that mission durations ranging from 4-6 months show a maximum loss of 30% muscle performance and maximum loss of 15% muscle mass.
Their propod mission not only calls for many months in space to get to Mars, but for tho volunteering to spend the rest of their lives living on the Martian surface. However, they also claim that they intend to lower the numbers and that their astronauts will be "well prepared with a scientifically valid countermeasures program that will keep them healthy, not only for the mission to Mars, but also as they become adjusted to life under gravity on the Mars surface." What the measures are remains to be en.
Learning more about Martian gravity and how terrestrial organisms fare under it could be a boon for space exploration and missions to other planets as well. And as more information is produced by the many robotic lander and orbiter missions on Mars, as well as planned manned missions, we can expect to get a clearer picture of what Martian gravity is like up clo. As we get clor to NASA's propod manned mission to Mars, which is currently scheduled to take place in 2030, we can expect more rearch efforts to be attempted.市场开发战略
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