空间大地测量学

空间大地测量学主讲：李征航 教授助教：刘万科 博士武汉大学测绘学院卫星应用工程研究所2008年09月空间大地测量学原子钟（Atomic

Clock）甚长基线干涉测量（VLBI）要3.激光测卫(SLR）卫星测高(Satellite

Altimetry)多普勒技术(Doppler

Technique）卫星跟踪卫星(SST)容

提Part

1.

Atomic

Clock

The

National

Physics

Laboratory

in

England

developed

the

firstaccurate

caesium

atomic

clock

in

1955

In

1967

the

International

Bureau

of

Weights

and

Measures

(BIPM)adopted

the

atomic

definition

for

an

SI

secondDefinition

of

Atomic

Second

:地面状态的铯133原子对应于两个超精细能级跃迁9

192

631

770个辐射周期的持续时间。

科学家当前正在研制更高精度的原子钟：

1

second

in

10

billion

yearsAtomic

Fountains(原子喷泉钟)15

fountains

in

operation

at

SYRTE,

PTB,

NIST,

USNO, Penn

St,INRIM,

NPL,

ON,

JPL.

6

with

accuracy

at

1×10-15

.

More

than

10

under

construction……A

Brief

History

of

Atomic

Clocks

at

NIST/cesium/atomichistory.htm

1945

--

Isidor

Rabi,

a

physics

professor

at

Columbia

University,suggests

a

clock

could

be

made

from

a

technique

he

developed

inthe

1930"s

called

atomic

beam

magnetic

resonance.

1949

--

Using

Rabi’s

technique,

NIST

(National

Institute

ofStandards

and

Technology)

announces

the

world’s

first

atomicclock

using

the

ammonia

molecule

as

the

source

of

vibrations.

1952

--

NIST

completes

the

first

accurate

measurement

of

thefrequency

of

the

cesium

clock

resonance.

The

apparatus

for

thismeasurement

is

named

NBS-1.NBS-1

1954

--

NBS-1

is

moved

to

NIST’s

new

laboratories

in

Boulder,Colorado.

1955--The

National

Physical

Laboratory

in

England

buildsthe

first

cesium-beam(铯原子束)clock

used

as

a

calibrationsource.

1958

--

Commercial

cesium

clocks

become

available,costing

$20,000

each.

1959

--

NBS-1

goes

into

regular

service

as

NIST"s

primaryfrequency

standard.

1960

--

NBS-2

is

inaugurated

in

Boulder;

it

can

run

for

longperiods

unattended

and

is

used

to

calibrate

secondarystandards.NBS-2➢1963

--

The

search

for

a

clock

with

improved

accuracy

and

stabilityresults

in

NBS-3.NBS-3➢1967

--

The

13th

General

Conference

on

Weights

and

Measuresdefines

the

second

on

the

basis

of

vibrations

of

the

cesium

atom;

theworld’s

timekeeping

system

no

longer

has

an

astronomical

basis.1968

--

NBS-4,

the

world’s

most

stable

cesium

clock,

iscompleted.

This

clock

was

used

into

the

1990s

as

part

of

the

NISTtime

system.➢1972

--

NBS-5,

an

advanced

cesium

beam

device,

is

completed

andserves

as

the

primary

standardNBS-5➢1975

--

NBS-6

begins

operation;

an

outgrowth

of

NBS-5,

it

is

one

of

the

world’s

most

accurate

atomic

clocks,

neither

gaining

nor

losing

one

second

in

300,000

years.➢1993

--

NIST-7

comes

on

line;

eventually,

it

achieves

an

uncertaintyof

5

x

10-15,

or

20

times

more

accurate

than

NBS-6.➢1999

----

NIST-F1begins

operation

with

anuncertainty

of

1.7

x

10-15,

or

accuracy

to

aboutone

second

in

20

millionyears,

making

it

one

ofthe

most

accurate

clocksever

made

(a

distinctionshared

with

similarstandards

in

France

andGermany).喷泉原子钟内部构造图Video

Demonstration

of

How

a

Cesium

Fountain

Works（喷泉钟的动画演示，请用鼠标点击上述画面）NIST-F1

Cesium

Fountain

Atomic

ClockThe

Primary

Time

and

Frequency

Standard

for

the

United

StatesThe

uncertainty

of

NIST-F1

is

continually

improving.

In

2000

theuncertainty

was

about

1

x

10-15,

but

as

of

the

summer

of

2005,

theuncertainty

has

been

reduced

to

about

5

x

10-16,

which

means

it

wouldneither

gain

nor

lose

a

second

in

more

than

60

million

years!

It

isnow

approximately

ten

times

more

accurate

than

NIST-7,

a

cesiumbeam

atomic

clock

that

served

as

the

United

State"s

primary

time

andfrequency

standard

from

1993-1999.Galileo

atomic

clocksRubidium

clockHydrogen

maser

clockGalileo

satellites

:

rubidium

atomic

frequency

standards

and

passive

hydrog

masers.

The

stability

of

the

rubidium

clock

is

so

good

that

it

would

lose

onl

three

seconds

in

one

million

years,

while

the

passive

hydrogen

maser

is

ev

more

stable

and

it

would

lose

only

one

second

in

three

million

years.Office

of

Naval

Research---"matchbox"

atomic

clockone

second

every

10,000

yearsUltra-miniature

Rubidium

(Rb)

Atomic

Clock,

40

cm3NIST

Chip-Scale

Atomic

ClockOn

Aug.

30,

2004

about

the

size

of

a

grain

of

rice

(1.5

millimeters

on

a

side

and

4millimeters

high),

consume

less

than

75

thousandths

of

a

watt(enabling

the

clock

to

be

operated

on

batteries)

and

are

stable

toone

part

in

10

-10,

equivalent

to

gaining

or

losing

just

one

secondevery

300

years.

the

physics

package

will

be

integrated

with

an

external

oscillatorand

control

circuitry

into

a

finishedclock

about1

cm3

in

size.Part

2.

VLBI-Very

Long

Baseline

Interferometry河外射电源（河外类星体）射电望远镜射电望远镜射电望远镜是一种能接收和处理来自太空的无线电信号的装置，由巨大的抛物面天线，高精度的原子钟，数据接收和处理设备等组成。灵敏度是指射电望远镜“最低可测”的能量值，此值越低灵敏度越高。为提高灵敏度常用的办法有

降低接收机本身的固有噪声、增大天线接收面

积、延长观测积分时间等。1)射电干涉测量分辨率指区分两个彼此靠近射电源的能力，分辨率越高就能将越近的两个射电源分开。利用射电望远镜进行观测时其角分辨率可用下列公式来估算：(2-1)式中

为角分辨率，

为射电望远镜所接收的无线电信号的波长，通常为13cm和3.6cm,

为射电望远镜接收天线的口径。那么，怎样提高射电望远镜的分辨率呢？对单天线射电望远镜来说，天线的直径越大分辨率越高。但是天线的直径难于作得很大，目前单天线的最大直径小于300米，对于波长较长的射电波段分辨率仍然很低，因此就提出了使用两架射电望远镜构成的射电干涉仪。对射电干涉仪来说，两个天线的最大间距越大分辨率越高。另外，在天线的直径或者两天线的间距一定时，接收的无线电波长越短分辨率越高。Arecibo

Observatory,National

Astronomy

and

Ionosphere

Center/The

Arecibo

Observatory

is

part

of

the

National

Astronomy

and

Ionosphere

Center(NAIC),

a

national

research

center

operated

by

Cornell

University

under

a

cooperativagreement

with

the

National

Science

Foundation

(NSF).阿雷西博(Arecibo)天文台，波多黎各（西印度群岛），USA直径：305m、51米深、1974年建成占地大约20英亩，40000块铝制面板组成，900吨的接收平台射线频率:50

MHz(6

m)~

10,000MHz

(3

cm).Green

Bank

Telescope

,

National

Radio

AstronomyObservatory

,West

Virginia

,USA世界上最大的钢结构的射电望远镜，直径100米，实际尺寸100×110

mNational

Radio

Astronomy

Observator/gbt1997年2月，日本空间科学研究所成功地发射了一颗VLBI空间观测研究卫星（VSOP），它可从东京分辨出悉尼的1颗米粒大小的东西,能在揭开黑洞结构等发挥重要的作用。2)

联线干涉测量为较大幅度的提高角分辨率，有人提出了联线干涉测量的方法（见右图）。通过此方法我们就组成了一台虚拟的口径为D的大射电

望远镜。此时D即

为两台射电望远镜的距离。VLA：Very

Large

ArraySocorro,

New

Mexico

，

USA提高角分辨率/VLA由27个射电天线组成一个Y字型，每个天线的直径是25mMERLIN,

operated

by

Jodrell

Bank

Observatory,

ithe

Multi-Element

RadioLinked

InterferometerNetwork,

with

separations

oup

to

217km.

It

operates

atfrequencies

ranging

from

15MHz

to

24

GHz.

At

5GHz,the

resolution

of

MERLIN

isbetter

than

50milliarcseconds,http://www.merlin.ac.uk/http://www.jb.man.ac.ukJodrell

Bank

Observatory

,University

of

Manchester.Jodrell

Bank的Lovell望远镜,1957年开始运行，跟踪了世界第一颗人造卫星Sputnik

1,其直径为76m由于下列原因：①

电缆价格较贵，且铺设电缆的工作量也较大。②

由于温度和外界环境的不同，两根电缆所产生的热胀冷缩及介电系数的变化也不相同，从而使A，B两个射电望远镜所接收的信号在送往相关器的过程中所花费的传送时间也不严格相同，从而影响结果的精度。这种误差会随着距离的增加而变大。所以联线干涉测量的距离一般被限制在几十公里以内，至今为止，最长的间距为217公里。基线干涉测量示VLBIVLBI现状及前景目前全球约有40~50个VLBI站

IVS(International

VLBI

Service

forGeodesy&Astrometry)EVNFAST

&

SKAIVS(International

VLBI

Service

for

Geodesy&Astrometry)

is

aninternational

collaboration

of

organizations

which

operate

orsupport

Very

Long

Baseline

Interferometry

(VLB

I)

components.The

objectives

of

IVS

are

to

provide

a

service

to

support

geodetic,

geophysical,

and

astrometricresearch

and

operational

activities;

to

promote

research

and

development

activities

in

all

aspects

of

thegeodetic

and

astrometric

VLBI

technique;

and

to

interact

with

the

community

of

users

of

VLBI

products

and

to

integrateVLBI

into

a

global

Earth

observing

system.IVS(InternationalVLBI

Service

for

Geodesy&Astrometry/

IVS

provides

data

and

products

for

thescientific

community.

Some

of

the

productsarea

terrestrial

reference

frame

(TRF),the

international

celestial

reference

frame

(ICRF),

andEarth

orientation

parameters

(EOP).All

IVS

data

and

products

are

archived

in

datacenters

and

are

publically

available

for

research

inrelated

areas

of

geodesy,

geophysics

and

astrometry..空间大地测量方法>VLBIhttp://ivscc.gsfc.naIsVaS.gNeotvw/ork

StationThe

European

VLBI

Network

(EVN)

was

formed

in

1980by

five

of

the

major

radio

astronomy

institutes

in

Europeand

Geodetic

Dept

of

the

University

of

Bonn.

Thefounding

radio

astronomy

institutes

were:MPIfR

in

Bonn,

GermanyIRA

in

Bologna,

ItalyASTRON

in

Dwingeloo,

The

NetherlandsOSO

in

Onsala,

SwedenJodrell

Bank

Observatory

(formerly

NRAL)

near

Manchester,

UKEVN:European

VLBI

NetworkEVN:European

VLBI

NetworkThe

European

VLBI

Network

(EVN)/上海天文台VLBI中科院乌鲁木齐天文台VLBI/25m射电望远镜南山观测基地VLBI站目前是全球和我国重要的地面参考点，射电望远镜接收系统的综合水平和观测状态已达到欧洲网的中上等水平。云南天文台40m射电天文望远镜

2006年安装，已经开始运行中科院云南天文台VLBI中科院国家天文台VLBI密云站50m天

线是我国目前最大的射电天线，它的建成和投入使用，将为国家天文台，乃至中国科学院承担更多的国家任务奠定基础条件。在“嫦娥工程”中，共有4台射电望远镜对“嫦娥一号”进行精确定位和观测,分别位于国家天文台北京密云地面站、云南天文台、上海天文台和乌鲁木齐天文台,共同组成VLBI网，结合上海天文台的数据处理中心共同组成测轨分系统对绕月探测卫星进行联合精确定位。这样一个网所构成的望远镜分辨率相当于口径为3000多公里的巨大的综合望远镜，测角精度可以达到百分之几角秒，甚至更高。VLBI测轨分系统的具体任务是获得卫星的VLBI测量数据，包括时

延、延迟率和卫星的角位置，并参与轨道的确定和预报。具体的

任务有完成卫星在24小时、48小时周期的调相轨道段的测轨任务，完成卫星在地月转移轨道段、月球捕获轨道段以及环月轨道段的

测轨任务。

“嫦娥一号”所获取的数据将源源不断地以无线电波的方式传送回地球，此时，四个观测站形成的“甚长基线阵”，将这些无线电波接收，然后集中发送到北京总部，经过科学家解码，还原成图片和数据，以此作为认识月球的依据。世界上最大的单口径500米的球面射电望远镜(five-hundred-

meter

aperturesphericaltelescope，简称FAST)，被科学家形象地形容为山谷中的“天眼”，科学家希望它能接收到来自某种

“地外文明”发出的信号。已被国家发改委立项，作为国家重大科技基础设施项目将在黔南布依族苗族自治州建设。该项目总投资6.27亿元，建设期为5年。项目拟采用我国科学家独创的设计和贵州省独特的喀斯特地形条件和极端安静的电波环境，建造一个500米口径球面射电天文望远镜，形成具有国际先进水平的天文观测与研究平台，为我国开展暗物质和暗能量本质、宇宙的起源和演化、太空生命起源和寻找地外文明等研究活动提供重要支持。它的建设对于改善我国科技基础设施条件，提升自主创新能力，增强科技竞争能力，促进原始性创新成果产生，带动高新技术发展具有极其重要的战略意义。我国的FAST计划FAST望远镜模似图贵阳一处喀斯特洼地SKA计划International

SKA

Project

Office/平方公里阵射电望远镜（SquareKilometreArray

简写为SKA）是计划中的下一代巨型射电望远镜阵，工作在0.10ˉ25GHz的波段，有效接收面积可以达到大约1平方千米，SKA的灵敏度将比目前世界上最大的望远镜高2个数量级。其将由上千台天线组成，其中有一半天线位于中央直径5公里的区域内，另有四分之一的天线散布在周围150公里的区域内，其余的分布在大约3000公里的范围内。目前，SKA的选址还未最终确定，澳大利亚、阿根廷、南非和中国都已被列入待选目标地之列。由于该望远镜的灵敏度极高，因此其建设地点必须远离大城市和各种无线电噪声源，同时，气候条件和地形也是必须考虑的因素。目前SKA已到其选址的关键时刻。建造它的主要目的是为了查明银河系中的重要结构和星系的演化过程。

SKA可以观测到宇宙空间一向不为人觉察的长波辐射。专家们解释说，在宇宙大爆炸时期形成的第一批星系至今仍在放射着长波，如果捕捉

到这些上百亿年前产生的辐射，便有可能揭示宇宙的演化进程。此外，科学家们同时表示，SKA还将被用来观测宇宙中的一些“暗物质”－－分布在星系间的稀薄气体。由于SKA在观测范围和灵敏度方面都远远超过了目前已有的同类型望远镜，其还有可能被用来搜索某些高智慧外星生物发出的微弱无线电波，以证实人们长期以来对外星生命的推测。SKA是目前最为庞大的国际科技合作项目之一，其耗资总额将达到

10亿美元之巨。2008年，SKA选址将确定。十年后，SKA将建成。2020年，SKA全面运行。届时，人类探索太空的视界将大大扩大，因为SKA的接收能力将比现有的射电望远镜强大50倍，巡天的速度更是超越现有射电望远镜1万倍。SAT的体积在世界望远镜史上前无古人。目前世界上最大的固定射电望远镜是美国阿雷西堡望远镜，直径为305米；最大的全可动射电望远镜是30年前德国建成的100米口径射电望远镜和不久前美国西弗吉尼亚州建成的探测面为110×100米的射电望远镜。这几乎已成为大型射电望远镜的工程极限。Siteranking‘1%

SKA’ScienceISSCMoAsSelectionInter-governmentaldiscussionsSiteFirst

SKAWorkingGroupInitial

concept‘10%

SKA’Science92060709102296

20020000

04{FeasibilitystudyFull

arrayBuild

100%

SKASKACompleteScienceCasepublished{05ConceptexpositionDefine

SKASystem{14{Phase

1Build10%

SKASKA

timeline18{OptimiseReferenceDesign{

{08Construct

1%

SKA“pathfinders”SKA计划的射电望远镜阵列澳大利亚的试验场SKA

Animation动画演示，请用鼠标点击上述画面Part

3.

SLR-Satellite

Laser

Ranging激光测卫示意图1）测距原理激光测卫（Satellite

Laser

Ranging）系统目前的测距精度可达1cm左右。图3-3激光测卫原理图GFZ的POTSDAM-2人卫激光测距仪2）激光测距仪3）激光反射棱镜神舟4号棱镜组CHAMP、GRACE卫星棱镜Starlette卫星4）激光测距卫星如前所述，凡是安装了后向反射棱镜，可对其进行激光测距的卫星称为激光测距卫星。①STARLETTE卫星该卫星是由法国航天局CNES于1975年2月6日发射的。该卫星是由20个三角平面组成的正20面体。直径为24cm，质量为47.295kg。Lageos-1卫星②Lageos卫星Lageos卫星是由NASA研制发射的，其中Lageos-1是1976年5月4日发射的，Lageos-2是1992年10月23日发射的。EGS（Ajisai）卫星③EGS（Ajisai）卫星Ajisai是日本于1986年发射的。卫星上安装了120组（1436块）反射棱镜，卫星的轨道倾角为50，卫星在高度为1500km左右的几乎是

圆形的轨道上运行。信号往返传播的时间为10~20ms。该卫星的优点是亮度大，目视星等达1.5~3.5，肉眼易见。④ETALON卫星Etalon-1和Etalon-2是前苏联于1989年1月和5月发射的。卫星的直径为129.4cm，质量为1415kg，卫星表面安放了306组反射棱镜，每

组中均含14个角反射棱镜，其中有6组为锗反射镜。Etalon_1卫星其它可进行SLR的卫星有T/P卫星、GPS卫星……TOPEX/PoseidonGPSPRN05（SVN35）

and

PRN06（

SVN36）

areequipped

with

corner-cube

reflectors

for

satelllaser

ranging

(SLR).Analyse

SV’s

Clock

Error

and

EphemerisErrorCheck

the

Ranging

Precision

of

SV5)现状及前景:目前全球约有50个左右的SLR固定台站以及少量的流动台站。测距精度已达到1~3cm.。少数台站已达到亚厘米级的精度水平。ILRS:International

LaserRanging

Service/

1981年以来我国在上海、武汉、长春、北京、昆明等地先后建立了SLR站。测距精度达到亚厘米级水平，并实现了白天观测。我国还自行研制了流动型SLR站TROS-1。武汉SLR台站中国流动卫星激光测距仪Beijing(TROS)上海天文台60厘米卫星激光望远镜SLR2000系统，NASA下一代的完全自动运行的SLR台站，单点测距精度优于3mm预计在不久的将来激光测距的精度还可能有较大的提高，达到mm级的测距精度。此外也有人提出在卫星上安装激光测距仪，在地面上安装廉价的反射棱镜以组成空基激光测距系统的建设。如能实现将进一步推动激光测距技术在大地测量中的广泛应用。/slr2000/Mission

&ApplicationGeodetic

MissionsThe

geodetic

satellites

are

so

named

for

theircontribution

to

determinate

and

measurementsthe

exact

positions

of

points

on

the

earth"ssurface;

the

shape

and

size

of

the

earth;

andthe

variations

of

the

terrestrial

gravity

andmagnetic

fieldsEarth

Sensing

MissionsThe

earth

sensing

satellites

carry

experimentsdesigned

to

sense

the

earth

(i.e

acquire

data

onworldwide

environmental

changes

such

as

thegreen

house

effect,

ozone

layer

depletion,tropical

rain

forest

deforestation,

and

abnormalclimatic

conditions),

in

order

to

contribute

tointernational

global

environmental

monitoringRadioNavigation

MissionsThe

radio

navigation

satellites

(Global

PositioningSystem

(GPS),

and

GLObal"naya

NavigatsionnaySputnikovaya

Sistema

(GLONASS))

are

UnitedStates

and

Russian

satellite

constellations,respectively.Experimental

MissionsThe

experimental

satellites

carry

diverseexperiments

that

do

not

fit

into

one

of

the

othermission

classifications

(i.e.

geodetic,

earth

sensing,positioning).

These

satellites

are

irregularly

shapedobjects

in

relatively

low

altitude

orbitsPart

4.

Satellite

Altimetry通过SLR、GPS、DORIS等

手段精确确定测高卫星的

运行轨道，同时又利用安

置在卫星上的雷达测高仪

测定至瞬时海水面间的垂

直距离来测定地球重力场，研究海洋学、地球物理学

中的各种物理现象的方法

和技术称为卫星测高

(Satellite

Altimetry)。卫星测高示意图1)测高卫星至今为止,在全球已发射如下测高卫星Skylab，Geos3，Seasat，Geosat，Ers-1，Topex/Poseidon，Ers-1，GFO，Envisat，Jason-1。表1部分测高卫星的基本参数卫星名称国名发射日期轨道高度（km）轨道倾角（度）工作寿命（年）覆盖周期

(天)测高精度(cm)Skylab美国1973.05.14425500.2585-100Geos-3美国1975.04.098401153.52.325-50Seasat美国1978.06.288001080.33

,1720-30Geosat美国1985.03.1280010841710-20Ers-1欧洲1991.07.1778598.533,

35

,16810Topex/Poseidon美/法1992.08.101336666106Ers-2欧洲1995.04.2178598.533,

35

,16810GFO美国1998.02.108001088173.5Jason-1美/法2001.12.071336665104.2Envisat欧洲2003.03.0180098.555354.5TOPEX/Poseidon卫星GFO卫星Envisat卫星Janson卫星TOPEX/Poseidon卫星上的高度计Part

5.

Doppler

Technology1)Transit/NNSS(Navy

Navigation

Satellite

System

)子午卫星系统（Transit）是美国海军研制、开发、管理的第一代卫星导航定位系统，又称为导航卫星系统（NNSS—Navy

Navigation

SatelliteSystem）。该系统采用多普勒测量的方法来进行导航和定位。Transit卫星及星座参数：卫星数：6颗轨道数：6个轨道夹角：30°轨道倾角：90°卫星高度：1075

km运行周期：107

min载波频率：400、150

MHzTransit

Constellation子午卫星星座OscarNova子午卫星多普勒定位示意图4导航定位原理2)DORIS(

Doppler

Orbitography

and

RadiopositioningIntegrated

by

Satellite)DORIS系统的组成DORIS跟踪系统示意图

DORIS

is

a

dual-frequency

Doppler

system

that

can

be

included

asa

host

experiment

on

various

space

missions,

Spot-2,

-3,

-4,

-5,

Topex/Poseidon,

Jason,

ENVISAT

and

Cryosat

in

the

future.

The

system

at

the

present

time

started

operation

in

1990.

Itspermanently

tracked

network

includes

50

beacons

evenly

distributedon

the

earth,

including

stations

on

all

major

tectonic

plates.

The

station

positioning

results

have

a

precision

of

1-2

cm,

and

dailypolar

motion

determinations

have

a

precision

of

about

1-2milliarcseconds.

The

geocenter

location

can

also

be

preciselymonitored

at

1-2

cm.International

DORIS

Service

(IDS).Map

of

the

current

DORIS

network(2008.02)International

DORIS

Service

(IDS)http://ids.cls.fr/Satellites

&

missions(2003)Doris

can

be

used

in

six

different

fields:Orbit

Determination

(orbitography)Earth

Gravity

Field、Rotation

studies、Precise

location、Satellite

navigationTime-taggingENVISAT-1

DORIS

stations

visibilities,

elevation

12°,

and

satellitetracks

for

1

day

(2007-03-07):九峰Doris

Station，中科院测地所Jiufeng

State,

Hubei

Country,CHINAhttp://ids.cls.fr/html/doris/stations/station.php3?code=JIUBPart

6.

SST---

Satellite-to-Satellite

Tracking高低模式(HL)低低模式(LL)高高模式(LL)高低模式(HL)1).CHAMP（CHAllenging

Mini-Satellite

Payload

)采用高低跟踪模式；由GFZ管理,执行重力场、磁场和大气探测研究GPS-CHAMP

high-low

satellite-to-satellite

and

ground

based

laser

trackinghttp://www.gfz-potsdam.de/pb1/op/champ/Front

Side

view

of

CHAMP

with

location

of

instrumentsRear

Side

view

of

CHAMP

with

location

of

instrumentsJPL"s

Blackjack

GPS

receiver470-km

alt<

5-cm

orbit

accuracy

GPS

Receiver

TRSR-2（

JPL-Built

Blackjack

Flight

GPSReceivers

）high-precision

orbit

determination

of

the

CHAMP

satellite.atmospheric

limb

sounding

experimental

use

of

specular

reflections

of

GPS

signals

from

oceansurfaces

for

GPS-altimetry.

A

synchronisation

pulse

delivered

every

second

is

used

for

preciseonboard

timing

purposes,The

receiver

has

the

following

measurement

modes:

Tracking

Mode

(default):

this

mode

is

enabled

as

soon

as

the

TSRS-2becomes

powered

up.

Occultation

Mode:

in

this

mode

the

receiver

software

schedules

every50

Hz

tracking

of

setting

occultations

of

up

to

four

GPS

satellites.

Altimetry

Mode:

in

this

mode

the

nadir

antenna

collects

specularreflections

of

GPS

signals

from

the

surface

of

the

oceans.Two

BlackJack

GPS

receivers

fromNASA"s

Jet

Propulsion

Laboratoryprovide

precision

orbit

determinationtiming

and

geolocation/index.phpICESat

(Ice,

Cloud,and

land

ElevationSatellite)

is

the

benchmark

EarthObserving

System

mission

for

measuringice

sheet

mass

balance,

cloud

and

aerosheights,

as

well

as

land

topography

andvegetation

characteristics.2).

ICESat

(Ice,

Cloud,and

land

Elevation

Satellite

)Video

On

Orbit动画演示，请用鼠标点击上述画面Video

On

Orbit动画演示，请用鼠标点击上述画面

BlackJack

GPS

flight

receivers

are

being

usedon

the

following

space

missions:

SRTM

(2000),SAC-C

(2000),

CHAMP

(2000),

JASON-1(2000/01),

VCL

(2000),

FEDSat

(2001),

ICESat(2001),

and

GRACE

(2001.

Other

JPL

Blackjack

GPS

flight

receivers

indevelopment:

COSMIC

(6

orbiters),

PARCS(Space

Station),

and

OSTM

(Jason-2).Shuttle

Radar

Topography

Mission(SRTM):

230-km

alt，45-cm

orbitaccuracy1336

km

ltitude2-cm

radial

orbits

(Topex

GPS

flightreceiver,

Motorola

built

to

JPL

specs1-cm

radial

orbits

(Jason-1

GPS

flighreceiver,

JPLBlackjack

design)SAC-C:

705-km

alt<

5-cm

orbitaccuracyBlackJack

is

a

dual-frequency

GPSreceiver

system

forprecise

(cm

accuracyrange)

orbitdetermination

andcontinuous

coverageWith

GPS

<

10

cmMicroLab/GPSMET730

km

altitude2002年发射升空，由德州大学的空间研究中心CSR、德国GFZ、美国的NASA和德国的空间飞行中心

DLR、美国的JPL共同研制，空间部分由相距约220km的GRACE卫星对组成，采用高低(HL)和低低(LL)跟踪相结合的模式。主要的科学任务为地球重力场恢复、大气探测。2).GRACE计划/grace/（Gravity

Recovery

And

Climate

Experiment）www.gfz-potsdam.de/pb1/op/grace/index_GRACE.htmlBlackjack

GPS

ReceiverGRACE:

500-km

alt2-cm

orbit

accuracyGRACE

Gravity

Model

01

based

on

111

days

of

GRACE

data.

Combined

gravity

field

model

EIGEN-GL04C

complete

to

degreeand

order

360

from

GRACE,

Lageos

and

surface

gravity

data,released

on

March

31,

2006MEO-MEO

Tracking利用星间观测值进行导航卫星的自主定轨（MEO-MEO）3)高高模式(High—high

Model)OCK

IIRPosition

of

monitor

stations

and

master

control

station

The

“master

control

station”

(Schriever

AFB)

and

four

additionalmonitoring

stations

(on

Hawaii,

Ascension

Islands,

Diego

Garcia

andKawajalein)

were

set

up

for

monitoring

the

satellites.

2005

8~9,

six

more

monitor

stations

of

the

NGA

(National

Geospatial-Intelligence

Agency)

were

added

to

the

grid.

Now,

every

satellite

can

beseen

fr