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美国太空史上又一个里程碑---

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美国东部时间3月2日02:49分，美国太空探索技术公司(SpaceX)的“猎鹰9号”火箭搭载着载人“龙”飞船从肯尼迪航天中心的LC-39A号发射台发射升空，执行首次无人试飞任务Demo-1。

LC-39A号发射台历史悠久，阿波罗在此离开月球，亚特兰蒂斯（Atlantis）最后一次航天飞行也是从此处发射。

在火箭发射升空大约10分钟后，猎鹰9号一级火箭成功在大西洋上的SpaceX海上无人船“当然，我依旧爱你”上着陆，这是SpaceX第35次成功完成一级火箭回收。

仅仅11分钟后，载人“龙”飞船就进入了预定轨道，它将于美国东部时间3月3日大约6点（北京时间3月3日19时）与国际空间站自动对接。

与国际空间站对接后，它将在那里停留五天。此次飞船将为国际空间站宇航员提供大约180千克的物资供应，然后在3月8日，SpaceX将带返回舱回到美国，并尝试用降落伞在大西洋着陆将研究样本带回地球。这次着陆将标志着这次试验任务实现了最后一个重要里程碑，并结束目前的飞行。

美国探索星空近30-40年是使用航天飞机，它可以重复使用，成本低，但是安全性不可靠。而最初的俄罗斯飞船只能用一次，成本高，但是只要逃生机制正常启动和运行，载人飞船的安全性就比航天飞机大得多。为了安全起见，美国已经于2011年起停用航天飞机。

“龙”飞船载人模型升空试验，既是美国本土航天飞船把宇航员送入太空的“关键第一步”，也是在为未来的太空旅游奠定基础。Space X的载人飞船的创新和改进之一就是试验成功了可重复使用的升空火箭，因而节约很多成本。再则，SpaceX将航天器自动对接到空间站的新工艺也是前所未有的。目前，随着科学发展，飞船现在可以多次往返使用。

这次无人试验飞行的成功，将向美国宇航员往返国际空间站，逐步摆脱对俄罗斯载人飞船的依赖大大地迈进一步。

“龙”飞船（Crew Dragon）将会是第一个将NASA宇航员送入轨道的商业航天器。而且“龙”飞船 和波音公司制造的名为Starliner的太空舱 – 将会结束美国长达十年来对俄罗斯人类太空飞行的依赖。

他们发射成功了！他们终于成功了！！！从三月一日开始，我就兴奋地关注着里程碑样的太空航行。

SpaceX首席执行官Elon Musk 说他"emotionally exhausted" “"It was super stressful, but it worked — so far.” 是的，在那雷鸣般的欢呼声之后，是多少人的血汗。十七年，这火箭，这飞船带走了多少人的年华，多少人的哽咽和欢喜，又带着多少人的梦想，哪是一声欢呼所能宣泄的。

我曾亲耳听到SpaceX工程师的太太们抱怨他们的先生是如何在重压下拼命。还好，我先生不在那工作，但是他在NASA工作时曾经为spaceX猎鹰9火箭做过技术验证。那些天，我也见证了一个工程师是怎样地呕心沥血。所以，今天，我也为他自豪一下。感谢猎鹰9带上了先生的脑电波升入太空。感谢上帝让他有幸参与如此重要的工作。

更多信息

New York (CNN Business)SpaceX's Crew Dragon capsule, its first spacecraft designed to carry humans, took flight for the first time Saturday.
An uncrewed demonstration mission took off from Kennedy Space Center in Florida early Saturday, en route to the International Space Station.
The successful launch without people puts SpaceX one step closer to an historic landmark: Crew Dragon could be the first commercially built spacecraft to carry NASA astronauts to orbit. And Crew Dragon — along with a capsule called Starliner built by Boeing — could end the United States' decade-long reliance on Russia for human spaceflight.
Elon Musk, SpaceX's chief executive and lead designer, told a crowd of reporters that he was "emotionally exhausted" after launch. His rocket company's main goal since it was founded in 2002 was to someday send humans to space.

"It's been 17 years to get to this point," he said. It took "an incredible amount of hard work and sacrifice from a lot of people to get to this point."
"It was super stressful, but it worked — so far. We have to dock with the station, and we have to come back," he added of the Crew Dragon launch, but some of the "riskiest" hurdles have been cleared.
SpaceX's capsule, carrying a dummy called Ripley, named for the "Alien" protagonist Ellen Ripley is expected to dock Sunday at the International Space Station, which flies about 254 miles above Earth at tremendous speeds: about 10 times faster than a bullet.
There, it will drop off about 400 pounds of supplies before it flies back home five days later.
SpaceX also dropped in a plush toy globe that flew around the cabin during flight to demonstrate when the capsule is in zero gravity.
This marks the first and only demo mission that Crew Dragon will fly without humans on board. If all goes well, the capsule design will undergo a few more reviews and safety checks, and it could be ready to fly two NASA astronauts to the space station in July, based on the space agency's current timeline.
After the Space Shuttle program retired in 2011, NASA turned for the first time to the private sector to build the next generation of human spaceflight hardware.
SpaceX and Boeing (BA) have contracts worth up to $2.6 billion and $4.2 billion, respectively.
Both project have been beleaguered with delays, and NASA and its oversight regulators have raised safety concerns that will have to be resolved before humans set foot on either spacecraft.
Meanwhile, NASA has paid Russia about $80 million per seat to send US astronauts to space aboard Soyuz rockets — a fact that isn't very popular in the halls of Congress.
Those Soyuz contracts were set to run out in 2019 and NASA recently moved to secure a couple more seats for late 2019 and the spring of 2020 in case Boeing and SpaceX aren't ready this year.
The space agency said in a statement last month that it has "confidence" the companies will be ready in 2019 and said the additional Soyuz contracts are meant to provide "flexibility and back-up" options.
Why Florida is still dominating the space launch game
Why Florida is still dominating the space launch game
The companies can still launch people this year — but things will have to go smoothly.
SpaceX aced a key NASA review ahead of Saturday's launch. If all goes well during the demo mission, the company will conduct a test on Crew Dragon's emergency abort systems in June. More safety checks are also in store.

SpaceX's first crewed mission, which will fly NASA astronauts Doug Hurley and Bob Behnken, could happen by July, according to NASA's most recent schedule.
Boeing's Starliner is slated to fly its first demo mission without a crew no earlier than April.

https://www.bbc.com/news/science-environment-47414390

https://www.space.com/elon-musk-spacex-crew-dragon-test-launch-success.html

https://www.zhihu.com/question/314292163

https://www.cnn.com/2019/03/02/tech/spacex-crew-dragon-demo-launch/index.html

后记

载人龙今天早上顺利完成了Demo-1飞行测试。美国东部时间上午8点45分该航天器在大西洋成功飞溅。 它被抬出海洋，安全地坐在Go Searcher Recovery船上的 SpaceX摇篮上。

载人龙返回面临两个非常重要的挑战

1穿越大气层时的高温灼烧

2更不对称的飞船的形状

尽管SpaceX有货运龙飞船成功返回的经验，但是载人龙装备有八个被称为SuperDracos的推进器这使得再次进入地球大气层时，大大增加了不稳定性。

在载人龙飞船的外壁的SuperDracos的推进器是用来防止飞行中发生重大灾难。如果出于某种原因，载着载人龙飞船的火箭在发射过程中出现问题，SuperDracos将被启动，并迅速将太空舱推送到安全地带。

这次飞行成功的意义

1 不仅将让NASA摆脱对俄罗斯飞船的依赖，还是向商业客户开放太空旅行的第一步。

更大空间，先进的硬件和软件，尤其是超大触控界面大幅提高飞船的自动化程度，降低航天员的学习难度和成本。

2为未来太空旅行迈出了更精彩的一步。

更低廉的成本，更舒适的环境，更先进的装备，为完成登陆火星计划的可容纳100名乘客的“星舰”，提供了重要的研发数据。