
一 | Political divisions are tearing our nation apart. Perhaps not since the last decade before our Civil War have differing perspectives so threatened the very fabric of American society. Many of us have seen similar forces in places like Iraq and Afghanistan produce unspeakable pain and tragedy and know that something must be done. But what?My military career taught me that young Americans, recruited from every corner of our nation, representing different races, religions, incomes, and accents can be brought together under a single flag, for a common purpose, and do great things. During the Depression they built roads, parks and other things that have contributed to every generation that followed. When World Wars I and II erupted, they united to protect not only America, but the world. They came together as diverse as our society, and built bridges, not just over rivers, but also to fellow citizens.Their greatest contribution was not any physical structure; it was in shaping themselves into what Tom Brokaw so aptly described as the "Greatest Generation." I might simply call them good citizens. We can, and must, do that again, by harnessing the power of letting young Americans serve something bigger than themselves. We can do it through what is often called national service. It is a simple concept: Young Americans come together for a year or two and work together in efforts as varied as healthcare, education, conservation, the military, or other community projects. For that period of their lives, before they go on to jobs, school, or family life, they work alongside other Young Americans serving fellow citizens and learning about each other – and themselves.

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三 | 据了解,长七A火箭是我国新一代中型运载火箭的主力构型,是在长征七号运载火箭和长征三号甲系列运载火箭三子级基础上、通过组合化设计形成的高轨三级液体捆绑式运载火箭,地球同步转移轨道运载能力不低于7吨,填补了我国运载火箭地球同步转移轨道5.5至7吨运载能力的空白,可适配直径4.2米和3.7米两种整流罩,具备一箭一星和一箭双主星发射能力。长七A火箭主任设计师魏远明在接受媒体采访时介绍,执行本次发射任务的长七A遥五火箭,采用4.2米直径整流罩的构型,全箭高度60.1米,与2021年3月12日发射的遥二火箭高度一致。

四 | 长七A火箭作为我国首型采用助推器与芯一级集束式分离技术的捆绑火箭,相比通常先分离助推器、再分离芯一级的方式,减少了一次分离环节,使火箭捆绑连杆结构更加简化。同时,集束式分离也减少了一个助推器落区,整个组合体都在一个落区内,更加有利于控制火箭残骸落区。此次任务是长七A火箭第四次执行发射任务,火箭状态正在逐步固化,同时为进入高密度发射阶段提前准备。魏远明介绍,型号队伍针对火箭技术设计进行了多项优化改进,在确保测试覆盖性的前提下,通过优化流程顺序、并行工作、合并测试等方法,将发射技术流程由32天缩减至26天。不仅如此,根据高轨卫星整体发展态势,以及高轨卫星配置大尺寸天线的迫切需求,长七A火箭未来还将研制5.2米整流罩的新构型,进一步提高火箭的任务适应性。
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