此次测试从美国海军的太平洋导弹靶场——夏威夷考艾岛的氦气球发射,是美国宇航局低密度超音速减速器(LDSD)技术演示项目的一部分,这个项目是为了测试在未来的火星任务中巨大制动降落伞和高速充气拖动设备。此装置旨在为又大又重的着陆器减速，使其从火星大气的超音速降到亚音速，最后安全、可控的降落。
The test, launched by helium balloon from the U.S. Navy’s Pacific Missile Range Facility in Kauai, Hawaii, was part of NASA’s Low Density Supersonic Decelerator (LDSD) technology demonstrator project, which is testing larger braking parachutes and inflatable drag devices at high speeds for future Mars missions. The devices will be needed to slow larger, heavier landers from the supersonic speeds of Mars atmospheric entry to subsonic approach speeds for safe, controlled landings.
虽然膨胀的减速器早已按计划部署,降落伞在减速到2马赫——从其位置被推到超音速气流时，还是会被撕成碎片。降落伞意想不到的失败使减速装置仍然附着在助推火箭上，导致了测试比预期更大的速度冲击了海洋。然而,试验装置成功恢复。
Although the decelerator device inflated and deployed as planned, the parachute was ripped to shreds after being pulled from its housing into the supersonic slipstream of the test unit as it decelerated to around Mach 2. The unexpected chute failure caused the inflated device, still attached to a booster rocket, to impact the sea at far greater speed than planned. The test unit was, however, recovered successfully.
加利福尼亚州,帕萨迪纳的美国宇航局喷气推进实验室的LDSD项目经理马克·阿德勒说,“有一天我们想把人类和更大的设备带到那里”。
"Someday we want to get humans there and larger structures," says Mark Adler, project manager for LDSD at NASA’s Jet Propulsion Laboratory in Pasadena, California.
测试评估了为机器人任务(SIAD-R)设计的直径约20英尺的超音速充气气动减速器,它使用了自动气囊发电机充胀热气体。此外，还测试了直径约110英尺的超音速降落伞系统，这明显比火星探测器“好奇者”的降落伞大。
The test evaluated a 20-ft.-dia. Supersonic Inflatable Aerodynamic Decelerator designed for robotic missions (SIAD-R), which uses automobile-derived airbag generators to inflate with hot gas. It also tested a 110-ft.-dia. supersonic parachute system, which is significantly larger than the 64.7-ft. chute used for the Mars Curiosity rover.
对于“好奇号”和以前所有着陆器,宇航局一直依赖1972年为维京登陆器收集的基本降落伞系统数据。阿德勒说,“新测试是需要的，因为我们有巨型设备要登陆火星”。
For the Curiosity mission and all previous landers, NASA relied on basic parachute system data collected in 1972 for the Mars Viking lander. "New tests were needed as we go to larger payloads to Mars," Adler says.
在2014年美国航空航天协会会议上,阿德勒说,测试的一个关键是正确模拟登陆火星的条件。“测试最困难的部分是让它们接近我们看到的火星的实际情况。因此我们必须到达190000英尺的高度(模拟稀薄的火星大气和低重力),让着陆器以4马赫速度到达那里。”
Speaking at the American Institute of Aeronautics and Astronautics Space 2014 conference here, Adler says a key challenge of the test was correctly simulating Mars entry conditions. "The hardest part of the test is to get them to close to the actual condition we see at Mars. So we have to get to 190,000 ft. altitude [to simulate the thin Martian atmosphere and low gravity] and get a full-size entry vehicle up there at Mach 4."
从120000英尺左右的气囊脱离之后,试验装置在ATK公司产的星—48固体火箭发动机助推下，以4.3马赫的速度提高到190000英尺。登陆器在71秒内旋转50转，在使用减速器之前继续上升。
Following release from the balloon at around 120,000 ft., the test unit was boosted to 190,000 ft. and Mach 4.3 by an ATK Star 48 solid rocket motor. The payload was spun to 50 rpm during the 71-sec. ascent before the SIAD was deployed.
阿德勒说,“从测试中我们希望看到，我们可以把登陆器发送到这个高度，速度也达到了试验条件,因此这个任务取得圆满成功,”接着他补充道，“减速器的成功部署直接减缓了着陆器的速度。”
"The first thing we wanted from the test was to show we could get the vehicle to altitude and up to speed to get to test conditions, and this mission was therefore a complete success," says Adler, who adds the SIAD deployed successfully and immediately slowed the vehicle.
他补充说，“减速气球(此设备帮助把降落伞打开)部署之后(甚至可能在部署之前),降落伞就被撕裂,我们宁愿看到这个在今年失败,而不是明年,因为这会影响到我们的成本和进度。从这个失败中我们学到了很多,因为我们有高速视频，借此我们可以观察这一系列现象，以前却没有。我们正在重新设计下一次飞行的降落伞。”
Following the deployment of the ballute (a device to help pull the parachute from its housing), the chute was ripped "before it could even deploy," he adds. "We would have rather seen this failure this year rather than next year because that would have had an impact on our cost and schedule. We learned a lot from this failure and because we had high-speed video we are now observing phenomena we have never seen before. We are now redesigning the parachute for the next flights."
两个装置计划于2015年进行测试,第一组的核心结构已经在喷气推进实验室安装。
Two units are scheduled for testing in 2015, the core structure for the first of which is already assembled at JPL.
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