双语译文关于NASA的小行星重定向技术试验器一些介绍

　　来源NSF APL
　　NASA’s Double Asteroid Redirection Test (DART) spacecraft has been moved to its secondary launch window as it begins thermal and environmental testing. The new launch date of November 24, 2021 is a delay from an original target of July 21.
　　DART is NASA’s first planetary defense demonstration, planned to change an asteroid’s orbit by a kinetic impact. DART is a simple technology demonstrator which will attempt to impact Dimorphos, a moonlet of the asteroid Didymos.
　　NASA’s Science Mission Directorate (SMD) senior leadership requested a risk assessment to determine the viability of the primary and secondary launch windows. After this assessment was completed, teams determined the primary launch window was no longer viable and the DART team was told to pursue the secondary date.
　　＂At NASA, mission success and safety are of the utmost importance, and after a careful risk assessment, it became clear DART could not feasibly and safely launch within the primary launch window,＂ said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate.
　　A part of the decision to move to the secondary date stems from the technical challenges of two main mission critical components: the Didymos Reconnaissance and Asteroid Camera for Optical-navigation (DRACO) imager and the roll-out solar arrays (ROSA). DRACO needs to be reinforced to handle the stress seen during launch and ROSA has had its delivery delayed due to supply chains impacted by the COVID-19 pandemic.
　　＂To ensure DART is poised for mission success, NASA directed the team pursue the earliest possible launch opportunity during the secondary launch window to allow more time for DRACO testing and delivery of ROSA, and provide a safe working environment through the COVID-19 pandemic.＂
　　While not the sole factor, the pandemic has made a large impact to the safety of personnel. The delay allows extra flexibility for the remaining spacecraft testing schedule, prioritizing the safety of people alongside mission success.
　　美国国家航空航天局(NASA)的双小行星重定向测试(DART)航天器已经转移到第二次发射窗口，开始进行热和环境测试。新的发射日期为2021年11月24日，比原计划的7月21日有所推迟。
　　DART是美国国家航空航天局(NASA)的第一个行星防御演示，计划通过动能撞击改变小行星的轨道。DART是一个简单的技术演示器，它将试图撞击小行星Didymos的小卫星Dimformos。
　　美国国家航空航天局(NASA)科学任务局(SMD)高级领导层要求进行风险评估，以确定主要和次要发射窗口的可行性。评估完成后，团队确定主要发射窗口不再可行，DART团队被告知继续进行次要日期。
　　NASA科学任务理事会副局长托马斯·祖尔布钦(Thomas Zurbuchen)说，＂在NASA，任务成功和安全是最重要的，经过仔细的风险评估后，很明显，DART不能在主要发射窗口内安全可行地发射，＂NASA科学任务理事会副局长托马斯·祖尔布钦(Thomas Zurbuchen)说。
　　决定转移到第二个日期的部分原因是两个主要任务关键部件的技术挑战：Didymos侦察和小行星光学导航相机(DRACO)成像器和推出太阳能电池板(ROSA)。DRACO需要加强以应对发射过程中出现的压力，由于供应链受到新冠肺炎疫情的影响，ROSA的交付已经推迟。
　　为了确保DART为任务成功做好准备，美国国家航空航天局指示团队在二次发射窗口寻求尽可能早的发射机会，以便有更多的时间进行DRACO测试和交付ROSA，并通过新冠肺炎疫情提供安全的工作环境。
　　虽然不是唯一的因素，但大流行对人员的安全造成了很大的影响。这一延迟为剩余的航天器测试时间表提供了额外的灵活性，在任务成功的同时将人员安全放在首位。
　　In the meantime, DART has completed major testing milestones. In November 2020, NASA and Aerojet Rocketdyne personnel installed the NASA Evolutionary Xenon Next-Commercial (NEXT-C) ion engine onto the spacecraft at the John Hopkins Applied Physics Laboratory (APL) .
　　＂The biggest part of that process was lifting the thruster bracket assembly off of the assembly table and positioning it at the top of the spacecraft,＂ said APL’s Jeremy John, the lead propulsion engineer on DART.
　　＂This took some care as the thruster’s propellant lines extended below the bottom of the bracket ring and could have been damaged if the lift was not performed properly.＂
　　Once the engine was lowered onto DART’s central cylinders, fasteners were installed to secure the thruster to the spacecraft. This then allowed APL to connect the electrical harnesses and propellant lines between the thrusters bracket assembly and DART. Afterwards, APL spent several days preparing and testing critical components to ensure a good integration.
　　With the NEXT-C engine installed, the spacecraft had both of its propulsion systems onboard. Along with the NEXT-C engine, it will use hydrazine thrusters as its primary propulsion system. The thrusters were installed in May 2020.
　　More of DART’s final systems then underwent integration as the spacecraft was prepared for environmental testing. After a pre-environmental review was held in January, the DART team was approved to begin thermal vacuum testing.
　　＂We’ve worked very hard to get to this critical point in the mission, and we have a great idea of spacecraft performance going into our environmental tests,＂ said APL’s Elena Adams, DART mission systems engineer.
　　＂We have an experienced team that is confident with the spacecraft’s ability to withstand the rigors of testing in the next month,＂ added Ed Reynolds, DART project manager at APL.
　　与此同时，DART已经完成了主要的测试里程碑。2020年11月，NASA和Aerojet Rocketdyne的工作人员在约翰·霍普金斯应用物理实验室(APL)的航天器上安装了NASA进化氙气NEXT-C离子发动机。
　　APL的杰里米·约翰(Jeremy John)是DART的首席推进工程师，他说：＂这一过程的最大部分是将推进器支架组件从装配台上抬出来，并将其放置在航天器的顶部。＂
　　＂这需要小心，因为推进器的推进剂管路延伸到支架环底部以下，如果升力不正确，可能已经损坏。＂
　　一旦发动机降到DART的中心气缸上，紧固件就被安装起来，将推进器固定到航天器上。这使得APL能够连接推进器支架组件和DART之间的电线束和推进剂管路。之后，APL花了几天时间准备和测试关键组件，以确保良好的集成。
　　随着Next-C发动机的安装，航天器上有两个推进系统。与Next-C发动机一起，它将使用肼推进器作为其主要推进系统。推进器于2020年5月安装。
　　随着航天器为环境测试做准备，DART的更多最终系统随后进行了集成。在1月份进行了环境前审查后，DART团队获准开始热真空测试。
　　APL的DART任务系统工程师埃琳娜·亚当斯(Elena Adams)说：＂我们非常努力地在任务中达到这个临界点，我们对航天器性能在环境测试中的表现有很好的想法。＂
　　APL的DART项目经理埃德·雷诺兹(Ed Reynolds)补充说：＂我们有一支经验丰富的团队，对航天器在下个月经受住严酷测试的能力充满信心。＂
　　Thermal vacuum testing will be done throughout spring. Once testing is complete, the spacecraft will then be equipped with the ROSA and DRACO. After those are installed, additional vibration and shock testing will take place before it is delivered to Vandenberg Air Force Base in California for launch on a SpaceX Falcon 9.
　　DART will launch from Space Launch Complex 4-East (SLC-4E) on a flight-proven Falcon 9, B1063. The booster first supported the Sentinel-6 Michael Freilich mission in November 2020. B1063 may support other missions from Vandenberg prior to launching DART in November 2021.
　　SpaceX’s Vandenberg manifest includes a pair of commercial launches: the SARah-1 mission for the German military, and the WorldView Legion Flight 1 launch as early as September.
　　Additionally, SpaceX will launch their second dedicated rideshare mission for their smallsat rideshare program, Transporter-2, no earlier than June. The classified NROL-87 mission for the National reconnaissance Office is also scheduled for no earlier than June.
　　Falcon 9 B1063 may support any of these missions prior to DART. It is also possible, but unlikely, that B1063 won’t fly any missions between Sentinel-6A and DART.
　　热真空测试将在整个春季进行。一旦测试完成，航天器将配备罗莎和德拉科。安装完成后，将进行额外的振动和冲击测试，然后将其交付到加利福尼亚州的范登堡空军基地，以便在SpaceX猎鹰9号上发射。
　　DART将乘坐经过飞行验证的猎鹰9号B1063从太空发射综合体4-East(SLC-4E)发射。助推器首次支持哨兵6号迈克尔·弗莱里奇任务是在2020年11月。在2021年11月发射DART之前，B1063可能会支持范登堡的其他任务。
　　SpaceX的范登堡清单包括两次商业发射：为德国军方执行的莎拉-1任务，以及最早在9月份发射的Worldview Legion Flight 1。
　　此外，SpaceX将不早于6月份为他们的小卫星拼车计划Transporter-2启动他们的第二次专门的拼车任务。国家侦察局的NROL-87机密任务也计划不早于6月。
　　猎鹰9号B1063可以在DART之前支持这些任务中的任何一个。B1063也有可能，但不太可能，不会在哨兵-6A和DART之间执行任何任务。
　　No matter the scenario, B1063 will launch DART on a trajectory to the Didymos binary system. After liftoff, the booster will perform a Return to Launch Site (RTLS) landing at Landing Zone 4 (LZ-4), directly adjacent to the launch pad.
　　DART is a demonstration mission for future technologies. It is a simple spacecraft that doesn’t include any scientific payloads. Weighing only 500 kilograms, it includes one main instrument, DRACO. DRACO is a camera which will help target the Didymos system while in coast.
　　One of the technologies to be tested is the aforementioned NEXT-C ion engine. NEXT-C is based on the NASA Solar Technology Application Readiness (NSTAR) engine which was used on the Dawn and Deep Space 1 spacecrafts.
　　NEXT-C was developed by the NASA Glenn Research Center and Aerojet Rocketdyne and designed to have improved performance, thrust, and fuel efficiency compared to other ion engines. NEXT-C is not the primary propulsion system, but its inclusion on DART will help demonstrate its potential for use on future deep-space missions.
　　Another technology demonstration is the aforementioned ROSA solar arrays. ROSA is a new type of solar panel that is designed to be more efficient and less bulky than other standard solar panels.
　　ROSA was first demonstrated on the International Space Station, after launch on the SpaceX CRS-11 mission in June 2017. It completed all but one of its mission objectives when the solar array failed to lock back in its stowed configuration.
　　New, larger types of ROSAs will be launched in 2021 and 2022 on the SpaceX CRS-22, CRS-25, and CRS-26 missions. Called iROSA, six arrays will be launched to help power the ISS for many years to come.
　　无论哪种情况，B1063都将在通往Didymos双星系统的轨道上发射DART。升空后，助推器将在直接靠近发射台的着陆区4(LZ-4)执行返回发射场(RTLS)着陆。
　　DART是未来技术的示范任务。这是一个简单的航天器，不包括任何科学有效载荷。它的重量只有500公斤，其中包括一种主要乐器-德拉科(Draco)。德拉科是一种照相机，它将在海岸上帮助瞄准Didymos系统。
　　其中一项要测试的技术是前述的Next-C离子发动机。Next-C基于美国宇航局太阳能技术应用就绪(NSTAR)引擎，该引擎用于黎明和深空一号宇宙飞船。
　　Next-C是由NASA Glenn研究中心和Aerojet Rocketdyne联合开发的，与其他离子发动机相比，其设计具有更高的性能、推力和燃油效率。Next-C不是主要的推进系统，但将其纳入DART将有助于展示其在未来深空任务中的使用潜力。
　　另一个技术演示是前面提到的ROSA太阳能电池板。ROSA是一种新型太阳能电池板，其设计比其他标准太阳能电池板效率更高，体积更小。
　　罗莎于2017年6月在SpaceX CRS-11任务中发射后，首次在国际空间站上展示。当太阳能电池板未能锁定其堆放的配置时，它完成了所有任务目标，只剩下一个目标。
　　新的、更大类型的ROSA将于2021年和2022年在SpaceX CRS-22、CRS-25和CRS-26任务上发射。被称为iROSA的六个阵列将被发射，以帮助国际空间站在未来几年内提供动力。
　　DART will also be equipped with thrusters, star trackers, and several sun trackers to help navigate itself to Didymos. Once it reaches the Didymos system, DART will then target and impact Dimorphos at 6.7km/s sometime in the first weeks of October 2022.
　　Dimorphos is the moonlet of the asteroid Didymos (Greek for twin). The system was discovered in April 1996 by the Kitt Peak National Observatory, when the asteroid was in close proximity to Earth. Dimorphos was given its name in June 2020.
　　The system is currently in a 1 AU by 2.2 AU orbit around the Sun. The impact with Dimorphos should cause the speed to change by 0.5 millimeters per second and alter the orbit of Dimorphos around Didymos.
　　DART will carry a CubeSat called Light Italian CubeSat for Imaging of Asteroids (LICIA) which will be released five days prior to impact to provide communications and images of the impact.
　　DART itself is one of two missions in a joint NASA and European Space Agency (ESA) program called the Asteroid Impact & Deflection Assessment (AIDA). AIDA’s main objective is to understand the effects of an asteroid impact by a spacecraft.
　　DART还将配备推进器、恒星跟踪器和几个太阳跟踪器，帮助自己导航到Didymos。一旦它到达Didymos系统，DART将在2022年10月的头几周某个时候以6.7公里/秒的速度瞄准并影响迪莫罗斯。
　　迪莫诺斯是小行星迪迪莫斯(希腊语中的双胞胎)的小卫星。该系统是1996年4月由基特峰国家天文台发现的，当时这颗小行星离地球很近。迪莫福斯于2020年6月取名。
　　该系统目前围绕太阳的轨道为1AU×2.2AU。与迪莫诺斯的撞击应该会导致速度每秒改变0.5毫米，并改变迪诺福斯围绕迪迪莫斯的轨道。
　　DART将搭载一颗名为＂意大利之光立方体卫星＂的小行星成像立方体卫星(LICIA)，该卫星将在撞击前五天发布，以提供撞击的通信和图像。
　　DART本身是美国国家航空航天局(NASA)和欧洲航天局(ESA)名为小行星撞击和偏转评估(AIDA)的联合计划中的两个任务之一。Aida的主要目标是了解小行星被航天器撞击的影响。
　　The ESA will conduct a follow-on mission called Hera, launching on Ariane 6 in 2024. Hera will arrive at the binary system in 2027 to observe the changes made by DART’s impact.
　　Hera is also a simple spacecraft, weighing about 1,050 kilograms and equiped multiple cameras and a LIDAR Laser Altimeter to determine how effective the impact from DART was in changing Dimorphos’ orbit.
　　Hera will also use new autonomous navigation systems while at Dimorphos to will test better and more efficient navigation methods for future interplanetary missions.
　　Hera will also carry two CubeSats. The first CubeSat is the Asteroid Prospector Explorer (APEX). APEX will perform surface measurements of two asteroids. Once its main surface data is gathered, APEX will attempt to land for up-close observations of the surface.
　　The second CubeSat is called Juventas and will line up with Hera to perform a satellite-to-satellite radio experiment and a low-frequency radar survey of the asteroid interior.
　　Once Hera’s mission is complete, Hera will land on one of the two asteroids. The landing will provide insight into the surface material of the asteroid.
　　The AIDA program is the first one of many Planetary Defense programs for NASA and ESA. NASA currently operates the OSIRIS-REx mission, which collected a sample from the Asteroid Bennu in October 2020. The samples will help NASA protect Earth from near-Earth Asteroids. The samples will be returned to Earth in 2023.
　　欧空局将执行一项名为赫拉(Hera)的后续任务，于2024年在阿丽亚娜6号(Ariane 6)上发射。赫拉将在2027年到达双星系统，观察DART撞击带来的变化。
　　赫拉也是一艘简单的航天器，重约1050公斤，配备了多个相机和一台激光雷达激光高度计，以确定DART的撞击在改变迪莫诺斯轨道方面的效果如何。
　　赫拉还将使用新的自主导航系统，而在迪莫罗斯，赫拉将为未来的星际任务测试更好、更有效的导航方法。
　　赫拉还将搭载两颗立方体卫星。第一颗立方体卫星是小行星勘探者探测器(APEX)。APEX将对两颗小行星进行表面测量。一旦收集到主要的表面数据，APEX将尝试着陆，对表面进行近距离观察。
　　第二颗立方体卫星名为尤文图斯，将与赫拉联手进行卫星对卫星无线电实验，并对小行星内部进行低频雷达探测。
　　一旦赫拉的任务完成，赫拉将降落在这两颗小行星中的一颗上。这次着陆将提供对小行星表面物质的洞察。
　　AIDA计划是美国国家航空航天局(NASA)和欧洲航天局(ESA)众多行星防御计划中的第一个。NASA目前正在运行OSIRIS-REX任务，该任务于2020年10月从小行星本努采集了样本。这些样本将帮助NASA保护地球免受近地小行星的伤害。这些样本将于2023年返回地球。
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　　↑视频简介NASA’s DART, the Double Asteroid Redirection Test, recently had its massive solar array ＂wings＂ installed at APL. The Roll-Out Solar Array (ROSA) technology provides a compact form and light mass for launch. It will then deploy into two large arrays once DART is in space. Each ＂wing＂ extends 8.6 meters – just over 28 feet – in length. The solar arrays on DART will use the same technology tested on the International Space Station. Using ROSA as the structure, a small portion of the DART solar array is configured to demonstrate Transformational Solar Array technology.
　　The APL-developed Transformational Solar Array technology has very high-efficiency solar cells and reflective concentrators. This additional technology on ROSA will provide three times more power than current solar array capabilities. The Roll-Out Solar Arrays will provide power to the spacecraft, allowing it to direct itself into its target, the binary asteroid system Didymos. DART will be the first-ever space mission to demonstrate asteroid deflection by kinetic impactor.
　　美国国家航空航天局(NASA)的双小行星重定向测试(DART)最近在APL安装了其巨大的太阳能电池板＂翅膀＂。滚装太阳能电池板(ROSA)技术为发射提供了紧凑的外形和轻质的质量。一旦DART进入太空，它将部署到两个大型阵列中。每个＂翅膀＂的长度为8.6米(28英尺多一点)。DART上的太阳能电池板将使用与国际空间站相同的测试技术。使用ROSA作为结构，DART太阳能电池板的一小部分被配置为展示变革性的太阳能电池板技术。
　　APL开发的转换式太阳能电池板技术拥有非常高效率的太阳能电池和反射式聚光器。ROSA上的这项额外技术将提供比目前太阳能电池板能力多三倍的电力。展开的太阳能阵列将为航天器提供电力，使其能够直接进入其目标双星小行星系统Didymos。DART将是有史以来第一次展示小行星由动能撞击器偏转的太空任务。
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　　↑视频简介NASA’s DART, the Double Asteroid Redirection Test, is a carefully planned experiment that will help determine if kinetic impactor technology—hurtling a spacecraft, toward a rocky body at speeds of about 13,000 miles per hour with the intention of pushing it off course—can serve as a reliable method of asteroid deflection in the event that such a hazard ever heads for the Earth.
　　The recently installed Roll-Out Solar Arrays (ROSA) are critical technology that will enable the DART spacecraft to navigate through space and effectively reach the Didymos asteroid system. The flexible and rollable ＂wings＂ are lighter and more compact than traditional solar arrays despite their size; in space, each array will slowly unfurl to reach 28 feet in length, about the size of a bus. The technology was first demonstrated on the International Space Station in 2017 and again this past June, but DART will be the first spacecraft to fly the new arrays, paving the way for their use on future missions. Deployable Space Systems (DSS), the manufacturing company out of Goleta, California, which developed the technology, delivered ROSA to APL in May and worked closely with the APL team in the following weeks to install them onto the spacecraft.
　　美国国家航空航天局(NASA)的双小行星重定向测试(DART)是一项精心设计的实验，它将有助于确定动能撞击器技术--以每小时约1.3万英里(约合1.3万公里)的速度将航天器撞向一个岩石天体，目的是将其推离轨道--是否可以作为一种可靠的小行星偏转方法，以防此类危险发生在地球上。
　　最近安装的滚装太阳能阵列(ROSA)是使DART航天器能够在太空中导航并有效到达Didymos小行星系统的关键技术。灵活可卷的＂翅膀＂比传统的太阳能电池板更轻、更紧凑，尽管它们的尺寸很大；在太空中，每个电池板都会慢慢展开，长度达到28英尺，大约一辆公交车的大小。这项技术于2017年首次在国际空间站上展示，并于今年6月再次展示，但DART将是第一个飞行新阵列的航天器，为它们在未来的任务中使用铺平道路。加州戈莱塔的制造公司Deploable Space Systems(DSS)开发了这项技术，该公司在5月份将ROSA交付给APL，并在接下来的几周里与APL团队密切合作，将其安装到航天器上。
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　　↑视频简介Earth moves through a dangerous neighborhood.
　　Astronomers estimate there are about 1,000 near-Earth asteroids larger than 1 kilometer—big enough to cause a global disaster. About 90 percent of them have been identified. Far less is known about smaller asteroids. All told, about 100 tons of extraterrestrial matter falls onto Earth every day, mostly in the form of harmless dust and an occasional meteorite.
　　NASA＂s Double Asteroid Redirection Test (DART) will be the first ever space mission to demonstrate asteroid deflection by kinetic impactor on a binary asteroid target: the smaller asteroid of Didymos, called Didymos B. Didymos is Greek for ＂twin.＂
　　DART is directed by NASA and undertaken by a team led by Johns Hopkins University Applied Physics Laboratory with support from NASA Goddard Space Flight Center, NASA Johnson Space Center, and the Jet Propulsion Laboratory. The Planetary Defense Coordination Office within NASA＂s Science Mission Directorate is the lead for planetary defense activities and is sponsoring this mission.
　　DART is planned to intercept the secondary member of the Near-Earth Asteroid Didymos binary system in October 2022.
　　地球穿过一个危险的区域。
　　天文学家估计，大约有1000颗近地小行星的直径超过1公里，足以造成一场全球灾难。其中大约90%的人已经被确认。人们对较小的小行星知之甚少。每天总共有大约100吨地外物质落到地球上，大部分是无害的尘埃，偶尔还会有一颗陨石。
　　NASA的双小行星重定向测试(DART)将是有史以来第一次展示小行星通过动能撞击器对双星小行星目标造成偏转的太空任务：较小的Didymos小行星，名为Didymos B.Didymos在希腊语中是＂双胞胎＂的意思。
　　DART由NASA指导，由约翰·霍普金斯大学应用物理实验室领导的一个团队承担，并得到NASA戈达德太空飞行中心、NASA约翰逊航天中心和喷气推进实验室的支持。NASA科学任务局内的行星防御协调办公室是行星防御活动的牵头机构，并赞助这项任务。
　　DART计划在2022年10月拦截近地小行星Didymos双星系统的二级成员。
　　Perched atop a stand in the middle of a high-ceilinged clean room, DART is beginning to look like the intrepid spacecraft that will aim itself directly into an asteroid next fall. With the addition of its compact Roll-Out Solar Arrays (ROSA) coiled into two gold cylinders that flank the sides of the spacecraft, and its less visible but still integral imager, the Didymos Reconnaissance and Asteroid Camera for Optical (DRACO) navigation tucked safely beneath its panels, the spacecraft is close to fully integrated.
　　This mix of current and new technologies, some of which it will demonstrate for the first time, will see DART through its 10-month journey toward its asteroid target.
　　NASA’sDART, the Double Asteroid Redirection Test, is a carefully planned demonstration that will help determine whether kinetic impactor technology — flying a spacecraft directly into a small solar system body at speeds of about 15,000 miles per hour with the intention of changing its course — can serve as a reliable method of asteroid deflection in the event that such a hazard ever heads for Earth. NASA is constantly monitoring the skies and has already identified nearly 40% of potentially hazardous asteroids larger than 140 meters (459 feet) in size, none of which are slated to impact our planet, including the binary system selected for this first-ever deflection test.
　　But to prove that our planet can expect the unexpected, the DART mission will set out to push an asteroid and safely change its motion in space. For the last two years, the spacecraft destined for this undertaking has been developed and built at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland. APL, which leads the mission for NASA, is now putting the finishing touches on the spacecraft.
　　The recently installed ROSA and DRACO are two critical technologies that will enable the spacecraft to navigate through space and reach the Didymos asteroid system. The flexible and rollable modular ＂wings＂ are lighter, more compact and stiffer than traditional solar arrays despite their size; in space, each array will slowly unfurl to reach 28 feet in length — about the size of a bus. The technology was first successfully tested in 2017 on the International Space Station (ISS), and newer versions were installed this past June for full-time use on the ISS. DART will be the first spacecraft to fly the new arrays, paving the way for their use on future missions. Redwire developed the technology at their Goleta, California, facility and delivered ROSA to APL in May, working closely with the APL team in the following weeks to carefully install them onto the spacecraft.
　　And whileDRACOis not entirely ＂new＂ (it was inspired by theNew Horizons LORRIcamera), this upgraded imager will be the sole instrument onboard the spacecraft. Combined with theautonomous navigation software SMART Nav(Small-body Maneuvering Autonomous Real-Time Navigation), it will play the key role in helping DART navigate through space and identify the correct asteroid to aim itself toward.
　　＂Traditional navigation techniques would only get DART somewhere within about 9 miles of the target asteroid,＂ said APL’s Zach Fletcher, DRACO lead engineer. ＂To achieve our mission objectives, we need to remove the rest of that error via onboard optical navigation. DRACO starts supplying images to DART’s onboard autonomous navigation system more than 50,000 miles from its target, four hours before the impact, and is key to DART achieving a kinetic impact on Dimorphos.＂
　　The images DRACO returns of the target asteroid Dimorphos, including the last-second glimpse of its own impact site on the asteroid, will be crucial toward analyzing the results of the DART test and understanding how the asteroid was affected.
　　DART has been through its paces in the last several months, enduring a battery ofenvironmental testing and analysisas the final pieces of the craft started coming together. Likewise, the SMART Nav software has seen its fair share of testing so the team can confidently relinquish the reins on DART in the final hours before it collides into Dimorphos. With DRACO and ROSA on board, the DART spacecraft completed vibration testing in late July to ensure that all of its hardware is secure and ready for the rigors of launch.
　　The Light Italian CubeSat for Imaging of Asteroids, or LICIACube, contributed by the Italian Space Agency, will be one of the final components to hitch a ride on DART before it is delivered to the launch site this October. LICIACube will deploy roughly five days before the DART impact and capture images of the spacecraft’s final moments, the resulting ejecta plume, and the back side of the asteroid that DRACO will never see.
　　＂DART is the result of years of work by a dedicated team and partners who have overcome uniquechallengesto accomplish firsts in both technology development and planetary defense,＂ said DART mechanical engineer Betsy Congdon, who led the team during the installation. ＂With the successful installation and testing of two critical technologies, DRACO and ROSA, we’re very confident that DART is ready to complete its final system testing and reviews before shipping to the launch site.＂
　　This November, the spacecraft will launch on a SpaceX Falcon 9 rocket from Vandenberg Space Force Base near Lompoc, California. In the fall of 2022, DART will have its sights set on Dimorphos, the smaller moonlet orbiting the larger Didymos asteroid. Its collision with Dimorphos will change the speed of the moonlet’s orbit around the main body by several minutes. And despite being approximately 6.8 million miles away from Earth at the time of impact, the asteroid system will be visible to ground-based telescopes, which scientists will use to determine the exact change in the orbital period.
　　在一间天花板很高的洁净室中央的一个看台上，DART开始看起来像是一艘勇敢的航天器，明年秋天将直接瞄准一颗小行星。除了紧凑的卷起太阳能阵列(ROSA)卷成两个金色圆柱体，在航天器两侧，以及其较不明显但仍然完整的成像器，Didymos侦察和小行星光学导航相机(DRACO)安全地隐藏在面板下，航天器接近完全集成。
　　这种当前技术和新技术的结合，其中一些将首次展示，将使DART完成为期10个月的小行星目标之旅。
　　NASA的DART，即双小行星重定向测试，是一项精心计划的演示，将有助于确定动能冲击器技术--以每小时约1.5万英里的速度将航天器直接撞向一个小型太阳系天体，目的是改变其航线--是否可以作为一种可靠的小行星偏转方法，以防此类危险发生在地球上。美国宇航局一直在监测天空，已经发现了近40%的大小超过140米(459英尺)的潜在危险小行星，这些小行星都不会影响我们的星球，包括为首次偏转测试选择的双星系统。
　　但为了证明我们的星球可以预见到意想不到的事情，DART任务将开始推动一颗小行星，并安全地改变其在太空中的运动。在过去的两年里，用于这项任务的航天器是在马里兰州劳雷尔的约翰·霍普金斯应用物理实验室(APL)开发和建造的。领导NASA任务的APL现在正在对航天器进行最后的润色。
　　最近安装的ROSA和DRACO是两项关键技术，将使航天器能够在太空中导航，并到达Didymos小行星系统。与传统的太阳能电池板相比，灵活的、可滚动的模块＂翅膀＂更轻、更紧凑、更坚固，尽管它们的尺寸很大；在太空中，每个电池板将慢慢展开，长度达到28英尺-大约一辆公交车的大小。这项技术于2017年首次在国际空间站(ISS)成功测试，今年6月，更新的版本被安装在国际空间站上，供全职使用。DART将是第一个飞行新阵列的航天器，为它们在未来的任务中使用铺平道路。RedWire在他们位于加利福尼亚州戈莱塔的工厂开发了这项技术，并于5月份将Rosa交付给APL，在接下来的几周里与APL团队密切合作，将它们小心地安装到航天器上。
　　虽然DRACO并不是完全＂新＂的(它的灵感来自新地平线LORRI相机)，但这个升级后的成像器将是飞船上唯一的仪器。与自主导航软件SMART NAV(小体机动自主实时导航)相结合，它将在帮助DART在太空中导航和识别要瞄准的正确小行星方面发挥关键作用。
　　APL的Draco首席工程师扎克·弗莱彻(Zach Fletcher)说：＂传统的导航技术只能将DART带到距离目标小行星约9英里的某个地方。＂为了实现我们的任务目标，我们需要通过机载光学导航消除该错误的其余部分。Draco开始向DART的机载自主导航系统提供图像，距离目标5万英里以上，也就是撞击前4个小时，这是DART实现对迪莫诺斯的动力冲击的关键。
　　德拉科返回的目标小行星迪莫弗洛斯的图像，包括它自己在小行星上撞击地点的最后一秒钟的一瞥，对于分析DART测试的结果和了解小行星是如何受到影响至关重要的。
　　在过去的几个月里，DART一直在经历着它的步伐，随着飞船的最后几块开始组装起来，它经受了一系列的环境测试和分析。同样，智能导航软件也经历了相当一部分的测试，因此团队可以在DART撞向迪莫罗斯之前的最后几个小时自信地交出对它的控制权。在德拉科和罗莎的陪同下，DART航天器在7月下旬完成了振动测试，以确保其所有硬件都是安全的，并为发射的严酷环境做好了准备。
　　由意大利航天局捐赠的用于小行星成像的意大利轻型立方体卫星(LICIACube)将是今年10月交付发射场之前搭乘DART的最后部件之一。LICIACube将在DART撞击前大约五天部署，并捕捉航天器最后时刻的图像，由此产生的喷发羽流，以及德拉科永远看不到的小行星背面。
　　DART机械工程师Betsy Congdon在安装过程中领导了DART机械工程师Betsy Congdon说：＂DART是一个专注的团队和合作伙伴多年来努力工作的结果，他们克服了独特的挑战，在技术开发和行星防御方面都取得了第一。＂