21日5時(shí)28分，我國在西昌衛(wèi)星發(fā)射中心用長征四號(hào)丙運(yùn)載火箭，成功將探月工程嫦娥四號(hào)任務(wù)“鵲橋”號(hào)中繼星發(fā)射升空。

A Long March-4C rocket carrying a relay satellite, named Queqiao, is launched at 5:28 am Beijing Time from Southwest China's Xichang Satellite Launch Center, May 21, 2018.[Photo/Xinhua]

China launched a relay satellite early Monday to set up a communication link between Earth and the planned Chang'e-4 lunar probe that will explore the mysterious far side of Moon, which can not be seen from Earth.

中國于21日凌晨發(fā)射中繼衛(wèi)星，將為將來實(shí)施的嫦娥四號(hào)月球背面軟著陸探測任務(wù)提供地月間的中繼通信。

The satellite, named Queqiao (Magpie Bridge), was carried by a Long March-4C rocket that blasted off at 5:28 a.m. from southwest China's Xichang Satellite Launch Center, according to the China National Space Administration (CNSA).

據(jù)中國國家航天局消息，這顆衛(wèi)星名為鵲橋，由長征四號(hào)丙運(yùn)載火箭于5時(shí)28分在西昌衛(wèi)星發(fā)射中心發(fā)射升空。

這是世界首顆運(yùn)行于地月拉格朗日L2點(diǎn)（簡稱地月L2點(diǎn)）的通信衛(wèi)星，將為2018年底擇機(jī)實(shí)施的嫦娥四號(hào)月球背面軟著陸探測任務(wù)提供地月間的中繼通信。

"The launch is a key step for China to realize its goal of being the first country to send a probe to soft-land on and rove the far side of the Moon," said Zhang Lihua, manager of the relay satellite project.

中國航天科技集團(tuán)有限公司五院“鵲橋”號(hào)中繼星項(xiàng)目經(jīng)理張立華說，“鵲橋的發(fā)射是中國成為首個(gè)實(shí)現(xiàn)探測器月球背面軟著陸和巡視勘察的國家的關(guān)鍵一步。”

長征四號(hào)丙運(yùn)載火箭飛行25分鐘后，星箭分離，將“鵲橋”直接送入近地點(diǎn)高度200公里，遠(yuǎn)地點(diǎn)高度40萬公里的預(yù)定地月轉(zhuǎn)移軌道，衛(wèi)星太陽翼和中繼通信天線相繼展開正常。

About 25 minutes after liftoff, the satellite separated from the rocket and entered an Earth-Moon transfer orbit with the perigee at 200 km and the apogee at about 400,000 km. The solar panels and the communication antennas were unfolded.

perigee ['perid?i:]：近地點(diǎn)

apogee ['?p?d?i]：遠(yuǎn)地點(diǎn)

后續(xù)，“鵲橋”將經(jīng)中途修正、近月制動(dòng)和月球借力，進(jìn)入月球至地月L2點(diǎn)的轉(zhuǎn)移軌道，通過3次捕獲控制和修正后，最終進(jìn)入環(huán)繞地月L2點(diǎn)的使命軌道，地月L2點(diǎn)是衛(wèi)星相對于地球和月球基本保持靜止的一個(gè)空間點(diǎn)。

Queqiao is expected to enter a halo orbit around the second Lagrangian (L2) point of the Earth-Moon system, about 455,000 km from the Earth.

It will be the world's first communication satellite operating in that orbit.

科普：地月拉格朗日L2點(diǎn)

the second Lagrangian [l?'gr?nd?i?n] (L2) point of the Earth-Moon system

拉格朗日點(diǎn)又稱為平動(dòng)點(diǎn)，于1772年由法國數(shù)學(xué)家拉格朗日推算得出，是指一個(gè)小物體在兩大物體的引力作用下，小物體相對于它們基本保持靜止的空間點(diǎn)。

該空間點(diǎn)有五個(gè)，分別為L1、L2、L3、L4、L5。在拉格朗日點(diǎn)上，探測器消耗很少的燃料即可長期駐留。

“鵲橋”號(hào)中繼星項(xiàng)目經(jīng)理張立華說，“鵲橋”還攜帶了由荷蘭研制的低頻射電探測儀，未來將開展在軌科學(xué)探測試驗(yàn)。

執(zhí)行此次發(fā)射任務(wù)的長征四號(hào)丙運(yùn)載火箭是長征四號(hào)系列運(yùn)載火箭第一次在西昌衛(wèi)星發(fā)射中心承擔(dān)發(fā)射任務(wù)。這是長征系列運(yùn)載火箭第275次發(fā)射。此次還搭載發(fā)射了“龍江一號(hào)”“龍江二號(hào)”兩顆月球軌道編隊(duì)超長波天文觀測微衛(wèi)星。

為什么要搭建地月“鵲橋”？

由于月球繞地球公轉(zhuǎn)的周期與月球自轉(zhuǎn)的周期相同，所以月球總有一面背對著地球，這一面稱之為月球背面。

著陸在月球背面的探測器由于受到月球自身的遮擋，無法直接實(shí)現(xiàn)與地球的測控通信和數(shù)據(jù)傳輸。

“鵲橋”號(hào)中繼星將在地月連線延長線的L2點(diǎn)附近，圍繞L2點(diǎn)飛行，實(shí)現(xiàn)對地、對月中繼通信，保障嫦娥四號(hào)任務(wù)實(shí)施，其到月球的平均距離約為6.5萬公里，距地球40多萬公里。

Chinese scientists and engineers hope the Queqiao satellite will form a communication bridge between controllers on Earth and the far side of the Moon where the Chang'e-4 lunar probe is expected to touch down later this year.

中國科學(xué)家和工程師希望“鵲橋”號(hào)中繼星能夠成為架設(shè)在月球背面與地球之間的“通信中繼站”。嫦娥四號(hào)月球背面軟著陸探測任務(wù)將在年底擇機(jī)實(shí)施。

綜合：新華社 央視新聞

來源：中國日報(bào)雙語新聞，編輯：左卓