The US military has successfully tested a .50-caliber sniper round that can change direction on its way to its target.
美军成功测试了一款50口径的狙击子弹，在向目标发射的过程中可改变方向。
And now the Defense Advanced Research Projects Agency (Darpa) has released a video of this Extreme Accuracy Tasked Ordnance (Exacto) program in action.
美国国防先进研究项目局公布了这个“高精度目标武器”项目的视频。

The footage shows the bullet changing direction in mid-air in response to a target's movements.
视频中，子弹可根据目标物体的移动而在半空中改变方向。
According to Darpa: 'For military snipers, acquiring moving targets in unfavourable conditions, such as high winds and dusty terrain commonly found in Afghanistan, is extremely challenging with current technology.
根据美国国防先进研究项目局的说法：“对于狙击手来说，在目前的技术条件下，要想在不利的环境中瞄准移动的目标是非常不容易的，比如在阿富汗这种风大尘土飞扬的环境下。”

'It is critical that snipers be able to engage targets faster, and with better accuracy, since any shot that doesn't hit a target also risks the safety of troops by indicating their presence and potentially exposing their location.'
“让狙击手更快更精准的锁定目标是非常重要的，因为如果没有狙击中的话，就会暴露狙击手，从而对军队的安全构成威胁。”
Darpa claims the new system is the first ever guided small caliber bullet.
美国国防先进研究项目局称这个新系统是首款制导的小型口径子弹。
'The Exacto .50-caliber round and optical sighting technology expects to greatly extend the day and night time range overcurrent state-of-the-art sniper systems,' continued the agency.
“这款叫做Exacto的50口径光学瞄准技术将大大的扩展目前最先进狙击系统的作战时间跨度。”

'The system combines a manoeuverable bullet and a real-time guidance system to track and deliver the projectile to the target, allowing the bullet to change path during flight to compensate for any unexpected factors that may drive it off course.
“这套系统将一种机动的子弹同一款实时的制导系统组合在一起，从而追踪目标并发起攻击，并且可在空中根据情况来调整飞行方向。”
'Technology development in Phase II included the design, integration and demonstration of aero-actuation controls,power sources, optical guidance systems, and sensors.
“第二阶段的技术研发包括了航空刺激系统的设计、整合和演示，以及动力来源，光学导航系统和传感器。”
'The program's next phase includes asystem-level live-fire test and technology refinement to enhance and improveper formance.'
“这个项目的下一个阶段将包括系统水平的实弹测试和技术方面的精细化，从而加强和提高性能。“
The current world record for the longest certified kill was by Corporal Craig Harrison of the UKHousehold Cavalry, who killed two Taliban in November 2009 from 1.54 miles (22.4km).
目前世界最长距离的狙击记录保持者是来自英国皇室卫队的下士Craig Harrison，他在2009年11月份击毙了22.4公里外的两名塔利班成员。
The shot was approximately 3,000ft (914 metres) beyond the stated maximum range of the Accuracy L115A3 sniper rifle, used by Corporal Harrison.
这个距离比这个下士所使用的L115A3狙击步枪的最大射程还要多出914米。

The Taliban were so far away it took each round almost three seconds to reach its target.
这两名塔利班成员离得那么远，以至于每一枪都要历时3秒钟才击中了目标。