1

Observations. Sat05_71.ppt, 2005-11-28.

• Directions: • satellite visible with stars as background.• Direction to radio-source (VLBI)

• Directions and distances: if satellite carries reflectors

2

Stellar-triangulation. Sat05_71.ppt

3

Global network. Sat05_71.ppt

4

West-European Network.sat05_71.ppt

5

North-American Network:

First results for Greenland

6

Distances. Sat05_71.ppt, 2005-11-28.

Reflected light: Lasers – 2-ways.

SLR= Satellite Laser Ranging.

http://ilrs.gsfc.nasa.gov/

http://www.eos-aus.com/satellite_laser_ranging.htm

Satellite emits signal: 1 way or two ways.

http://www.gfz-potsdam.de/pb1/op/prare/prare.html

7

Laser http://msl.jpl.nasa.gov/QuickLooks/lageosQL.html

8

LAGEOS

9

Earth-Moon system

10

Distance measurements. Sat05_71.ppt, 2005-11-28.

Signal:

Impuls:

Phase:

waves.ofnumber integer N

distance.way -2 ,)(2

1

Nrij

λ Δλ

11

Integer ambiguity. Sat05_71.ppt, 2005-11-28.

N may be determined using

• Signal with several frequencies

• Several observations

12

Distance-differences. Doppler. Sat05_71.ppt, 2005-11-28.

.Observations:

)( and )( 3221 tBtBtBtB

13

Satellite Altimetry. Sat05_71.ppt, 2005-11-28.

Geos-3, GSFO

SEASAT

Topex/Poseidon, Jason,

ERS1 + 2, Envisat

and

CRYOSAT

Satellite

Water – Ice - Plains

14

Satellite-to-Satellite Tracking. Sat05_71.ppt, 2005-11-28.

CHAMP, from GPS to satellite

GRACE. from GPS to two satellites and ranging between the satellites

GOCE, from GPS to the satellite

.

15

Interferometry. Sat05_71.ppt, 2005-11-28.

http://www.jb.man.ac.uk/vlbi/

16

VLBI. Sat05_71.ppt, 2005-11-28.

http://lupus.gsfc.nasa.gov/brochure/bintro.html

.

17

Results. Sat05_71.ppt, 2005-11-28.

.