【视频】ULA 火神火箭复飞推迟一天：氮气厂断电，载 40 颗 Amazon Leo 卫星周六中午再升空
联合发射联盟（ULA）的火神（Vulcan）火箭原定 11 月 13 日在佛罗里达州 Cape Canaveral 太空军基地 41 号发射场升空、把 40 颗 Amazon Leo 宽带卫星送入近地轨道，但当天上午因一家氮气工厂断电被迫取消，发射改到美东时间周六 11 月 14 日中午 12 时 32 分，火箭与卫星状态良好。
ULA 在周五上午的声明中表示，这次推迟是由于 Air Liquide 气态氮工厂断电、高压泵停转，在无法确认供气持续稳定之前，团队决定改用备份发射机会。气态氮用于火箭与发射台系统的吹扫与增压。ULA 于美东时间上午 8 时 41 分宣布推迟，此时距原定升空还有 4 个多小时，发射团队已经开始给半人马座（Centaur V）上面级加注液氧。
这次任务编号 LV-01，是火神火箭自今年 2 月以来首次飞行。今年 2 月 12 日的 USSF-87 国家安全任务中，一枚固体助推器的喷管在升空约 20 秒后出现烧穿，这是火神前四次飞行中第二次出现喷管问题，美国太空军随后暂停了火神的国家安全发射。ULA 与助推器供应商 Northrop Grumman、太空军等机构联合调查后找出了三个可信原因，并对喷管的设计与制造都做了修改；调查仍在继续，太空军表示要看过这次商业飞行的飞行数据后，再决定是否恢复火神的国家安全任务。
LV-01 也是 Amazon 向 ULA 订购的 38 次火神发射中的第一次。40 颗卫星是 Amazon 单次发射数量最多的一批，载荷总重逾 50,000 磅，创 ULA 纪录。这枚编号 V-012 的火箭采用六枚固体助推器的 VC6L 构型，高 215 英尺，并首次使用为近地轨道优化的半人马座上面级：它高 35 英尺，比标准型短约 6 英尺、推进剂少三分之一，省下的重量用来多装卫星。
按计划，火箭升空约 70 分钟后开始释放卫星，共 16 次分离、历时约 25 分钟，目标轨道约 285 英里高、倾角 51.9 度。太空军第 45 气象中队预报周六发射场降雨概率为零、风速 10 至 15 节。Amazon Leo 星座首代规划逾 3,000 颗卫星，ULA 总裁兼首席执行官 Mark Peller 表示，每一次飞行都会产生数据，这次飞行将用来检验喷管改进措施在真实飞行中的效果。
（来源：联合发射联盟）
资料引用：Spaceflight Now
[Video] ULA Vulcan Return to Flight Slips One Day: Nitrogen Plant Outage Pushes Launch of 40 Amazon Leo Satellites to Saturday Midday
United Launch Alliance (ULA) had planned to launch its Vulcan rocket on November 13 from Space Launch Complex 41 at Cape Canaveral Space Force Station in Florida, carrying 40 Amazon Leo broadband satellites to low Earth orbit, but the attempt was called off that morning after a power interruption at a nitrogen plant; liftoff is now set for 12:32 p.m. Eastern on Saturday, November 14, with the rocket and satellites healthy.
In a statement Friday morning, ULA said the launch was delayed due to a power interruption in the Air Liquide gaseous nitrogen plant, which resulted in the loss of its high-pressure pumps, and that without confirmation of sustained commodity flow the team decided to realign the launch to the back-up opportunity. Gaseous nitrogen is used to purge and pressurize systems on the rocket and launchpad. ULA announced the delay at 8:41 a.m. Eastern, a little more than four hours before the scheduled liftoff and after the launch team had begun loading liquid oxygen into the Centaur V upper stage.
The mission, designated LV-01, is Vulcan's first flight since February. During the USSF-87 national security mission on February 12, a solid rocket booster nozzle appeared to suffer a burn-through about 20 seconds after liftoff, the second nozzle problem in Vulcan's first four flights, and the U.S. Space Force paused Vulcan's national security launches. A joint investigation by ULA, booster supplier Northrop Grumman, the Space Force and other agencies identified three credible causes and led to changes in both the nozzle's design and how it is built; the investigation continues, and the Space Force has said it wants to review data from this commercial flight before deciding whether Vulcan resumes national security missions.
LV-01 is also the first of 38 Vulcan launches Amazon has purchased from ULA. Its 40 satellites are the largest single batch Amazon has launched, with a payload of more than 50,000 pounds, a ULA record. The rocket, designated V-012, flies in the VC6L configuration with six solid rocket boosters, stands 215 feet tall, and uses the first low-Earth-orbit-optimized Centaur V upper stage: at 35 feet it is about six feet shorter than the standard version and carries a third less propellant, with the weight savings used to carry more satellites.
Under the flight plan, satellite deployments begin about 70 minutes after liftoff, in 16 separation events over about 25 minutes, into an orbit about 285 miles high at 51.9 degrees inclination. The Space Force's 45th Weather Squadron forecast a zero percent chance of rain at the launch site on Saturday, with winds of 10 to 15 knots. Amazon Leo's first-generation constellation is planned at more than 3,000 satellites. ULA President and CEO Mark Peller said every flight generates data, and that this flight would be used to assess the effectiveness of the nozzle corrective actions in a flight environment.
(Source: United Launch Alliance)
Reference: Spaceflight Now
来源：联合发射联盟
发布：GSM·美国（发布链接）
图片来源：图：装有 40 颗 Amazon Leo 卫星的整流罩在 Cape Canaveral 的 Amazon 垂直整合厂房内吊装（资料图）。联合发射联盟 ULA 官方发布。 / Photo: The payload fairing containing 40 Amazon Leo satellites being hoisted inside the Amazon Vertical Integration Facility at Cape Canaveral (file photo). United Launch Alliance official photo.
GSM Global · 本篇英文版 English edition of this story
