X37B介绍

Purpose
The X-37B is one of the world’s newest and most advanced re-entry spacecraft, designed to operate in low-earth orbit, 150 to 500 miles above the Earth. The vehicle is the first since the Space Shuttle with the ability to return experiments to Earth for further inspection and analysis. This United States Air Force unmanned space vehicle explores reusable vehicle technologies that support long-term space objectives.
Solution
The vehicle features many elements that mark a first use in space, including:
Avionics designed to automate all de-orbit and landing functions.
Flight controls and brakes using all electro-mechanical actuation; no hydraulics on board.
Built using a lighter composite structure, rather than traditional aluminum.
New generation of high-temperature wing leading-edge tiles and toughened uni-piece fibrous refractory oxidation-resistant ceramic (TUFROC) tiles.
Advanced conformal reusable insulation (CRI) blankets.
Toughened uni-piece fibrous insulation (TUFI) impregnated silica tiles.
The X-37B has a lifting body-style and landing profile that is similar to the Space Shuttle, but the vehicle is one-fourth the size. The X-37B design combines the best of aircraft and spacecraft into an affordable system that is easy to operate and maintain.
The on-orbit duration of the X-37B will vary based on flight requirements but has the ability to perform flights lasting up to 270 days.

X-37B空天战斗机
科普中国|审阅专家张辉
X-37B空天战斗机（英文：X-37B Space Plane[1]）[2]，是美国波音公司研制的无人且可重复使用的太空飞机。该机由火箭发射进入太空，是第一架既能在地球卫星轨道上飞行、又能进入大气层的航空器，同时结束任务后还能自动返回地面，被认为是未来太空战斗机的雏形。其最高速度能达到音速的25倍以上，常规军用雷达技术无法捕捉。
2014年10月17日，X-37B（OTV-3）已于完成连续飞行超过674天。
2020年5月17日，美军X-37B航天器在佛罗里达州卡纳维拉尔角空军基地发射升空。[3]
中文名X-37B空天战斗机
外文名X-37BSpace Plane
生厂公司波音公司
类型无人太空飞机
主要用户美国空军
第一代空天飞机失败
上世纪60年代初，美国空军将领就对空天飞机的性能做出一些要求，有关机构开始对空天飞机作探索性试验，当时它被称为“跨大气层飞行器”。20世纪60年代发展的X-15、X-23和X-24等方案，为后来的空天飞机研制奠定了重要的基础。由于当时的技术、经济条件相差太远，且应用需求不明确，因而中途夭折。
X-37B空天战斗机
80年代中期，在美国的“阿尔法”号永久性空间站计划的刺激下，一些国家对发展载人航天事业的热情普遍高涨，积极参加“阿尔法”号空间站的建造。当时估计，空间站建成后，为了开发和利用太空资源，向空间站运送人员、物资和器材等任务每年将达到数千次之多。这些任务如果用一次性运载火箭、载人飞船或航天飞机来完成，一年的运输费就将达到上百亿美元。为了寻求一种经济的天地往返运输系统，美、英、德、法、日等国纷纷推出了可重复使用的天地往返运输系统方案。
1986年，美国提出研制代号为X-30的完全重复使用的单级水平起阵的“国家航空航天飞机”，重点是对高超音速喷气式发动机技术进行研究，后来又将研究重点转移到了火箭动力航天飞机方面，为研制空天飞机打下基础。
1994～1996年，由美国空军大学、空军科学技术顾问委员会完成的一系列关于未来军事装备的研究报告均建议把空天飞机作为今后20～30年最重要的武器装备之一。1996年7月，美国宇航局和洛马公司签订了一项协议，由洛马公司研制一种可重复使用的运载器技术验证飞行器，并进行飞行试验，以为研制和经营可完全重复使用的实用型运载器进行技术上的准备。该验证机代号为X-33，而最终要研制的实用型飞行器被称为“冒险星”。
X-33具备把11.35吨有效载荷送上国际空间站的能力，美国宇航局希望它能比老一代航天飞机节省90%的发射费用。如果研制成功，X-33将是美国第一代真正意义上的空天飞机。像第一代航天飞机一样，X-33的发射和降落将分别采取垂直发射和水平降落的形式，但它支持单级火箭运输，仅依靠自身发动机和内置燃料，无需任何外挂燃料的辅助燃烧动力就能进入轨道，不但能节省大量人力物力，同时还能缩短两次任务之间的准备时间。为了达到这一目标，设计者们开发了一种新型的气塞式火箭推动器，以使飞行器以18倍音速的速度飞行，同时，为减轻重量，X-33将采用新式的质量较轻的复合材料制造。但是，一些专家认为这些技术在当时并未成熟，将导致X-33的失败。
NASA研发的X-33飞行器
NASA原计划于1999年7月4日制造出样机，1999年7月26日进行马赫数为7的第一次飞行。但由于技术难度太大，X-33技术验证机的研制任务未能如期完成。2001年，在经过5年的研究，耗资12.6亿美元后，NASA和空军相继宣布取消X-33技术验证机的研制计划，但“冒险星”计划并没有被停止。洛马公司当时准备成立一家公司，称为“冒险星有限责任公司”，负责筹集制造和经营“冒险星”实用运载器所需的50亿美元资金。
美国空军虽未直接参与X-33项目，但却一直对这种技术十分关注，美国宇航局取消X-33项目后，美国空军太空司令部曾表示空军想要评估形势并有可能接管X-33计划的后勤支持，但迄今未知有进一步消息。

第二代空天飞机
1996年，NASA提出了Future-X计划。这个计划被拆成两个子计划，其中规模较小的“探险者”，就是X-37计划。这是因为X-33计划在1994年一度被冻结，影响到好几个关键技术的研究进度。为了让几个致力于太空运输方面的研究机构可以继续把他们的实验结果送上太空做高超音速的飞行验证，
从1998年底直到1999年7月，波音与NASA签署了4年合作协议，建造一系列验证机中的第一架。依照计划，X-37将成为第一架同时具备在地球卫星轨道上飞行和具备再入大气层能力的飞行器，而机上的自动操作系统将在NASA所致力的“降低进入太空的负载成本”上扮演关键性的角色。在原计划中，X-37可以由航天飞机携带进入太空，但是在有报告指出使用航天飞机携带X-37进入太空不合乎经济效益后，就改由“三角洲4”或是相似的火箭负责这个任务了。在太空中，X-37可以经由本身配备的火箭引擎推动，得到25倍音速的飞行速度，直到重入大气层前，X-37有21天的时间在太空中进行相关的实验，然后重返地球，降落在传统的跑道上。
试飞
2010年4月22日，美国空军花费10年研制的全新“空天战机”X-37B首次试飞。这种外形和功能都酷似小型航天飞机的战机将通过火箭送入轨道环绕地球飞行，然后再以滑翔方式返回地面。据悉，该机将从佛罗里达州卡纳维拉尔角空军基地升空，并且在加利福尼亚州着陆。[4]
发射
X-37B共进行了三个架次的飞行，第一架X-37B从美国佛罗里达州卡纳维拉尔角空军基地发射升空，同年12月降落加州范登堡，任务编号OTV-1；2011年3月5日，第二架X-37B（OTV-2）升空，发射工位仍然位于卡角，在轨运行时间469天，2012年6月返回，降落地点为加州范登堡；第三架X-37B（OTV-3）在2012年12月升空，已经完成了轨道任务。
2010年
2010年4月23日7点52分（美国东部时间4月22日19点52分），美国研制的人类首架太空战斗机X-37B从佛罗里达州卡纳维拉尔角空军基地SLC-41发射台成功发射升空，“阿特拉斯5号”火箭执行了此次发射任务。X-37B在战时，有能力对敌国卫星和其他航天器进行军事行动，包括控制，捕获和摧毁敌国航天器，对敌国进行军事侦察等等。
X-37B战斗机由“阿特拉斯5号”火箭发射升空
X-37B发射后进入地球卫星轨道并在太空遨游，X-37B在设计上能够执行最长为期270天的太空任务。结束太空之旅后，X-37B将进入自动驾驶模式返回地球，最后在加州范登堡空军基地或者附近备用基地——爱德华兹空军基地(VAFB)着陆。
这架X-37B无人驾驶太空飞机在当地时间2010年12月3日凌晨1点16分降落在美国加州范登堡空军基地。
但是，美国空军没有透露飞机的具体用途，也没有说明这次飞行所携带的物品。
这次X-37B安全着陆是太空飞机首次自主重返大气层，创下了新的纪录。对美国太空计划的发展具有重要意义。
2011年
2011年3月5日美国东部时间下午5时46分，美国佛罗里达州卡纳维拉尔角空军基地成功发射第二架由一枚“宇宙神—5”运载火箭搭载的X—37B轨道试验飞行器，计划飞行时间9个月，期满后延长6个月，于2012年6月16日成功返回地球。
X—37B长8.8米，实际上是一种“迷你航天飞机”，往返太空和地面，可重复使用。不过，这种“迷你航天飞机”并不搭载宇航员。　美国2010年发射第一架X—37B，运行224天于2010年12月3日返回地面。按照美国空军的说法，一旦投入使用，这种飞行器可以执行太空侦察、修复卫星等任务。
X-37太空战机在轨性能展示
X-37B由波音公司研制，首架曾在轨道运行225日。据悉，X-37B所有运作在升空后“自动进行”，无需地面人员遥控。[5]
2012年
2012年12月11日从卡纳维拉尔角空军基地成功发射。执行本次任务的X-37B与2010时发射的为同一架。这架X-37B的发射，使用的运载工具为阿特拉斯5型火箭，累计轨道飞行时间671天，打破了前一架次X-37B所保持的记录。[6]
2014年
2014年10月14日，X-37B（OTV-3）轨道飞行时间671天，美国空军“绝密级”X-37B迷你航天飞机可能返回，并降落在美国加州范登堡空军基地，空军的官员已经在范登堡空军基地准备迎接X-37B的降落。[6]
2014年10月17日，美国军方宣布，2012年12月从佛罗里达州卡纳维拉尔角发射升空的X-37B于当地时间当天上午9时24分（北京时间18日0时24分）在加利福尼亚州范登堡空军基地着陆。这是该飞行器执行的第三次试飞测试任务，也是迄今耗时最长的一次“秘密任务”。[7]
2015年
美国空军X－37B“轨道试验飞行器”将于2015年5月执行第四次在轨飞行任务。与此前3次任务高度保密、完全避谈细节

发展进程
项目起源
1999，美国宇航局选择波音综合国防系统集团轨道车辆的设计和开发，由波音公司加利福尼亚分公司的建立幻影工厂。在四年期间，总共有1亿9200万美元促成项目，NASA贡献109美元的万元，美国空军16美元万，和波音公司的67美元万。在2002年底，一个新的3亿100万美元的合同授予波音公司作为美国国家航空航天局的部分太空发射计划框架。
X-37的气动设计是来自大航天飞机轨道器，因此X-37有类似的升阻比，和较低的交叉范围在海拔较高的地区，Mach数相比于DARPA的高超音速技术飞行器。宇宙飞船被称为一个早期的要求速度增量7000英里每小时（3.1公里/秒）来改变它的轨道。对该程序的早期目标是X-37交会卫星和修理。X-37的最初目的是进入轨道的航天飞机的货舱，但经历了重新设计推出了三角洲IV或类似的火箭在确定了航天飞机的飞行将是不经济的。
X-37从NASA的国防高级研究计划局（DARPA）在13九月2004。此后，该节目成为分类项目。DARPA晋升X-37作为独立的空间政策，美国国防部一直以来，1986年“挑战者”号的灾难。
滑行试验
汽车，作为一个大气跌落试验滑翔机没有推进系统。而运营车辆的有效载荷舱门，它有一个封闭和钢筋上机身结构允许它交配一母舰。2004九月，DARPA宣布其初始大气跌落试验X-37将推出从攀登Composites White Knight，高空研究飞机。
这个攀登Composites White Knight用于发射的x-37a滑行试验。
六月21的2005，x-37a完成人工圈养下进行飞行的White Knight莫哈韦航天发射场进入莫哈韦沙漠，加利福尼亚。通过对2005下半年的x-37a进行结构升级，包括其加固前轮支持。进一步的俘虏进行飞行测试和第一滴试验，初步预计在二月中旬出现2006。X-37的公开亮相定于其月10日2006第一次自由飞行，但由于北极风暴取消。下一个航班的尝试，在15月2006日，因大风取消。

d space test platform designed to carry experiments to orbit and return them to Earth for evaluation.
U.S. Department of the Air Force photo
The U.S. Department of the Air Force and Boeing X-37B autonomous spaceplane has received the prestigious Robert J. Collier Trophy for the greatest American achievements in aeronautics and astronautics of 2019.
The National Aeronautic Association awarded the 2019 Collier to the X-37B for advancing the performance, efficiency and safety of air and space vehicles. Designed and built by Boeing, operated in partnership with the U.S. Space Force, and managed by the U.S. Department of the Air Force Rapid Capabilities Office, the X-37B is a reliable, reusable, uncrewed space test platform designed to carry experiments to orbit and return them to Earth for evaluation.
Originally designed for missions of 270 days, the X-37B has set endurance records during each of its five previous flights. Its first mission launched in 2010, and its latest mission began on May 17, 2020.
In 2019, the X-37B set a new 780-day on-orbit endurance record before landing at NASA’s Kennedy Space Center. The program has logged more than 2,865 days and traveled more than 1 billion miles on orbit in total.
This is the ninth Collier Trophy shared by the U.S Department of the Air Force and its forerunners, and Boeing and its legacy companies. Prior shared wins include iconic air and space achievement like the B-52, X-15, Global Positioning System and the C-17 Globemaster III.
First awarded in 1911, the trophy’s past recipients include Orville Wright; the Apollo 11 lunar landing team; the International Space Station, built by Boeing for NASA; the F/A-18E/F Super Hornet, built by Boeing for the U.S. Navy; and the Boeing 787, 777 and 747 commercial airplanes.

For the sixth time since 2010, the Boeing-built X-37B Orbital Test Vehicle has returned to orbit. The X-37B space vehicle began its latest mission on May 17, 2020, when it launched from Cape Canaveral Air Force Station aboard a United Launch Alliance Atlas V rocket.
The autonomous and reusable X-37B will perform experiments in low-Earth orbit while testing and integrating new reusable space vehicle technologies. This sixth mission will also carry unique experiments for NASA, the Naval Research Laboratory and the U.S. Air Force Academy.
Cadets from the Air Force Academy Astronautics Department, with assistance from Boeing, designed and built FalconSAT-8, a small satellite that will be deployed from the X-37B to test advanced propulsion technologies and collect important data for the Department of Defense. The U.S. Air Force Academy is the only undergraduate institution in the world where students help design, build, test, launch and operate small satellites.
Originally designed to fly 270 days per mission, the X-37B has set progressive records for time on orbit during each of its five previous missions. Most recently, it flew for 780 days before returning to Earth in October 2019.

In 2013, the Irish beer world record recognized the X-37 as the world’s smallest orbiting space shuttle. April 13,2015, the Space Foundation awarded the X-37 Team SPACE ACHIEVEMENT AWARD 2015 for “Substantially advancing the nation’s art and reusable spacecraft in orbit, the X-37B spacecraft has been designed, developed and tested over three missions for a total of 1,367 days in space.”The shape feature X-37B is manufactured by Boeing’s Phantom Factory, it weighs about 5 tons, is 8.8 meters long and 2.9 meters high, has a wingspan of 4.6 meters, and has two vertical tail fins on its tail. It looks like a sports car and is one fourth the size of the space shuttle. ; [ take-off weight exceeds 5 tons. The X-37B is about 29 feet long, 8.8 meters long, 9.5 feet wide, or 2.9 meters, and has a wingspan of about 15 feet, or 4.6 meters, which is nearly as long as an extended Rolls-Royce Phantom, as a result, the X-37B is larger than an orbiting satellite, but smaller than the space shuttle, and should be classified as a mini, not a Aerospaceplane, because it is launched using rockets, the X-37B, after all, can not take off horizontally. [6] built-in Cargo Bay X-37B’s built-in cargo bay is capable of reloading cargo, mechanical arms, then the X-37B in-orbit Verification Spacecraft’s navigation control technology, thermal protection materials, engine technology, space docking and manned capability are “Hidden”missions, the X-37B can be used by the U. S. military in different stages to develop a variety of classified missions. [6] the X-37B is small but functional, with a shuttle-like back payload bay the size of a pickup truck trunk, a notable feature of the X-37B, with a payload capacity of about two tons, the built-in cargo bay can carry a small robotic arm to launch orbital operations, such as grabbing enemy satellites in orbit, destroying spacecraft, releasing small payloads, and so on. To meet the X-37B’s on-orbit energy needs, it also carries solar panels to provide an.

The Power System X-37A was originally powered by high purity hydrogen peroxide and JP-8 kerosene. However, X-37B was changed to bipropellant of methyl hydrazine (MMH) and N2O4. Although MMH is highly toxic, the technology is more mature. The X-37B’s orbit maneuver ability is one of the key points of the US military test. Because the X-37B needs to detect and attack the enemy spacecraft, it needs to constantly change orbit. It is very important to have the orbit maneuver ability of different altitude, interestingly, the X-37B also needs to constantly change the orbit for defense, because the orbital garbage is too much, a little not careful may steal the chicken not to eat rice, by space debris hit and failure. [6] weapon configuration, although the X-37B is a low-orbit spacecraft with limited direct space combat capabilities, military experts believe it can carry advanced weapons such as missiles and laser launchers for long-range precision strikes, its operational potential can not be underestimated. The X-37B can quickly reach “Over”any target in the world, and use its own weapons to control, Hunt and destroy enemy satellites and other spacecraft, and even launch attacks against enemy ground targets. Thus, the X-37B has the possibility of becoming an “Orbital bomber”. Reconnaissance equipment, as of 2014, the US military’s space reconnaissance capability is mainly in the charge of the national reconnaissance office, but there are deficiencies such as slow operational response, high cost, etc. , so the Pentagon decided to develop the Aerospaceplane to make up for the lack of U.S. space reconnaissance capabilities. The X-37B can carry a variety of reconnaissance equipment, at high altitude to sea, land and air targets and outer space targets, and real-time reconnaissance information to the combat unit. If the drone is reliable, it could prompt the Aerospaceplane to deploy large numbers of low Earth orbit reconnaissance satellite quickly. [10]

The main function of the X-37B is to be put into orbit by a Atlas (mythology) rocket and generate the required electricity from the solar panels it carries. The X-37B can perform reconnaissance, navigation, control, infrared detection and return to the ground automatically after completing the mission. [6] X-37B photo: the plane slowed down to leave space and could land on a runway 4,600 meters long and 61 meters wide by Vandenberg Air Force Base. In orbit, the shuttle can gather information, launch small satellites, test space equipment and other work. The X-37B not only has the advantages of fast flight speed, long time staying in the air, low launch cost and so on, but also has the powerful reconnaissance and the attack potential. According to the Air Force, the reusable X-37B is only a quarter the size of the Space Shuttle in service. The X-37B can stay in orbit for 270 days. In wartime, the aircraft has the ability to conduct “Military operations”against enemy satellites and other spacecraft, including controlling, capturing and destroying enemy spacecraft, conducting all-round military reconnaissance of the enemy, and so on. As a result, the X-37B is likely to be mankind’s first space fighter. [6] the X-37B “Orbital test vehicle”program is run by the Air Force’s office of rapid response capabilities, and is developed and manufactured by the Phantom Factory, a unit of Boeing, the American aircraft giant. Two X-37B aircraft have been built. The X-37B is 8.8 m long and 2.9 m high with a take-off weight of about 5 tonnes and a wingspan of 4.6 m. The X-37B resembles a small unmanned space shuttle, but is only about a quarter the size of the space shuttle. The X-37B is capable of flying at hypersonic speeds of up to Mach 25 in 30-100 km of nearby space. All functions operate automatically during the flight without the need for remote control on the ground. The X-37B has a shuttle-like payload bay on its back, carrying a small robotic arm that can orbit once it reach

The X-37B is a continuation of the “Advanced concept technology demonstration and verification”developed by the US military. It aims to verify the technical results of the pre-development phase through flight tests to test the feasibility, operational applicability and economic affordability of the technology. At this stage, the Air Force’s rapid response capability office is primarily responsible for the testing and validation of the X-37B program. According to information published on the official website of the US Air Force, the X-37B will validate a range of hardware facilities and technical capabilities, including long-time in-orbit capabilities, payload capabilities such as X-band radars and robotic arms, sealing technology, thermal protection systems, solar power systems, and environmental modeling systems. The X-37B flew four missions in 2010,2011,2012 and 2014. On the eve of the fifth flight test, the US military revealed that the X-37B will carry an “Advanced structural embedded radiator”(ASETS-11) , the instrument, designed by the U.S. Air Force laboratory, can test electronic instruments and oscillating heat pipes in a space environment. [11] the X-37 is an unmanned Aerospaceplane that can be launched by a booster rocket or dropped by an aircraft and fly at high speed into orbit around an earth satellite. Because it is guided by remote control and has no cockpit, it is much smaller than a spacecraft, making it ideal for Aerospaceplane. With a wingspan of 4.57 meters and a length of about 9 meters, it can carry about 2 tons of cargo and is designed to fly at a high speed of 25,000 kilometers per hour in low Earth orbit. Conventional spacecraft, by contrast, weigh more than 90 tons and are 37 meters long. The X-37 program is connected to the X-33. The X-33 failed, but its re-launch design is of great commercial value for space transportation

Compared with conventional fighters, the X-37B, though small in size, is equipped with a powerful power unit. Launched by a rocket, it can travel at 25 times the speed of sound. At that speed, ground-based radar would have a hard time finding and tracking the X-37B’s trajectory. Powered by its own solar and lithium-ion batteries, the X-37B can fly for up to 270 days. [6] comparison of X-37B with other spacecraft: the X-37B’s orbital altitude also shows that the space platform can cover the orbits of most satellites, according to some Western observers, with an orbital altitude of up to 1,000 km, the X-37B could pose a potential threat to current satellites in a wide variety of orbits. After all, the X-37B is capable of capturing satellites, cruising in orbit, and performing a variety of regional missions. [6] as a reusable spacecraft, the X-37B should also have strong re-entry and autonomous control capabilities, as the X-37B can switch flight patterns between suborbital space and low-earth orbit, the atmosphere density of suborbital space is higher, and the environment of low Earth orbit is quite different from that of suborbital space, so X-37B’s thermal protection ability is stronger, all three X-37B sorties tested different levels of thermal protection and were able to study the aerodynamic characteristics of the X-37B, making it a low-cost, intelligent “Killer app”capable of rapid entry into orbit. [6]

x37的前任是x33，低配版是x40,升级版是x41

航天飞机是载人航天器，而 SMV是无人小型航天器。由于无人，不需要复杂的生命保障系统和救生系统，可以减轻许多结构重量。在军事应用上采取无人的形式，也更加适宜。
在X37B真机现身之后，人们又看到了更多的区别：
首先，X37B 与航天飞机气动外形上的最大区别，是将航天飞机的单尾翼，改为两个外倾立尾。这样，既改善了X37B的偏航性能，也降低了全机的高度，使其可以放入运载火箭整流罩内。X37B的头部在气动外形上也更钝一些。分析表明，X37B的气动外形在高超音速，大迎角（40度）条件下升阻比与航天飞机接近，但是在25度迎角下的升阻比低于航天飞机。不过在低速段（0.4马赫以下），小迎角下的升阻比优于航天飞机。这一设计使得X37B的低速飞行和定点着陆能力优于航天飞机。
其次，航天飞机在上升段由两个固体助推器和外部燃料箱，以及有主动力的轨道飞行器组成。它是一个并联的构型，结构复杂，导致易生事故。X37B则是用火箭顶推轨道器的串联构型，结构较简单可靠。这种构型避免了“哥伦比亚”号航天飞机外部燃料箱的隔热泡沫塑料块脱落后打坏轨道器防热瓦最终导致该机再入时烧毁的惨剧。
第三，X37B 虽小，但它的头部和机翼前缘的钝度有所增大，再入时气动热环境和航天飞机类似，头部和前缘的最高温度约为1627摄氏度，机身的最高温度约为1316摄氏度。头部和前缘采用了由艾姆斯研究中心研制的韧化整体纤维抗氧化复合材料（TUFROC），它比航天飞机使用的防热瓦更轻，但可以做得更厚、传热过程更慢而抗氧化性能更强。机体则大面积采用韧化整体纤维的绝热材料（TUFI）。此外，作为试验，在舵面上局部还使用了碳 / 碳化硅的防热材料。由于 X-37B 采用了较先进的防热系统，不仅提高了它在再入大气层时的安全性，而且大大减少了防热系统在地面维护和修理的工作量。
最后，略微说说X37B的机动能力。X37B确实可以在轨机动，但主要是进行轨道高度的机动，目前还没有发现它进行过轨道倾角有较大改变的机动。在2012年的第二次飞行中进行过倾角为0.88度的轨道外机动。今后若要改变轨道倾角，机动的范围也不会太大。根据NASA和美国海军的研究结果，在各种初始轨道高度上，Ｘ37B能获得最大的轨道平面改变能力不超过14°。所以，X37B的机动能力强大只是和以往的航天器相比。