美国发射最大绝密间谍卫星

According to the on November 22, the giant booster - a Delta Four Heavy rocket - blasted off at 5:58 pm from the Cape Canaveral Air Force Base in Florida carrying a new spy satellite NROL-32 for the US's National Reconnaissance Office into orbit on November 21.

NRO director Bruce Carlson said that the rocket would launch "with the largest satellite in the world on it." However, the exact purpose of the new spy satellite NROL-32 is secret。

For comparison, in July 2009 a satellite called TerreStar-One - touted as previous largest commercial satellite ever built– launched into space on July 7 in 2009. TerreStar-One is a 6, 9 kg satellite。

The Delta Four Heavy rocket is the US' biggest unmanned rocket currently and has two million pounds(about 0.91 million kg) of thrust, making it the most powerful liquid- fueled booster available currently. A Delta Four Heavy rocket stands 235 feet tall and is actually made up of three boosters。

The rocket made its first flight in 2004 and is capable of launching payloads of up to 24 tons into low-Earth orbit and 11 tons toward the geosynchronous orbits used by communications satellites。

In his address last month, Carlson said that the current plan for NRO satellite missions "is the most aggressive launch campaign that the National Reconnaissance Office has had in 20 years, almost a quarter of a century."据太空网站22日报道，21日下午5时58分，巨大的"德尔塔-4"重型火箭从美国佛罗里达州卡纳维拉尔角空军基地腾空而起，将美国国家侦察办公室所属的一颗绝密间谍卫星NROL-32送入轨道。

国家侦察办公室主任布鲁斯•卡尔森表示，"德尔塔-4"重型火箭将发射"世界上最大的卫星"。然而，这个最新间谍卫星NROL-32的具体性能却是一个谜。

此前世界上最大的卫星是2009年7月发射的TerreStar-1商业卫星，重达6.9吨。

"德尔塔-4"重型火箭是美国现在最大的无人驾驶火箭，具有两百万磅(约91万公斤)的推力，这让它成为目前最强大的液体燃料助推器。"德尔塔-4"重型火箭高235英寸，实际上是由三个助推器组成。

重型火箭在2004年进行首次发射，它可以将24吨重的负载发送到低地球轨道，也能将用于通讯卫星的11吨重的载荷送入地球同步轨道。

在上个月的报告中，卡尔森表示，目前国家侦察局卫星计划的使命是"国家侦察局20多年以来，几乎算四分之一个世纪以来最具进攻性的发射活动"。