../KBRPartialFixAccelerationConstrainedPCV 05 335
1
Contact: dr. ir. P.N.A.M. Visser E-mail: [email protected] Faculty of Aerospace Engineering Astrodynamics and Space Missions The Astrodynamics & Space Missions group at the Faculty of Aerospace Engineering is one of the leading centers in the world for precise orbit determination. Our group is regularly selected by the European Space Agency (ESA) to compute precise orbits for their satellites. To compute our orbits we use and co-develop software from the NASA Goddard Space Flight Center and the DLR German Space Oper- ation Center. We use state-of-the-art models for density in the atmosphere and the gravity field. We maintain our own infrastructure of servers to efficiently process the terrabytes of data coming from the satellite sensors. With our expertise and facilities we have improved the accury of many satellite orbits down to the cm level. Not only do we understand the environment of the satellite, we also look at the applications of the satellites. The orbits computed by our group are used to measure ocean currents, sea level rise and in support of measuring the effect of earthquakes, for example in Sumatra and Japan. Examples of satellite missions the group has been working on include the geopotential missions CHAMP, GRACE, GOCE and Swarm, the altimeter missions TOPEX/Poseidon, ENVISAT and CryosSat-2, and the lunar mission SELENE. CHAMP (Jul 2000 - Sep 2010) GRACE (Mar 2002 - 2019) GOCE ( Mar 2009 - 2013) Swarm (Early 2013 - 2018) AOES/Medialab AOES Medialab Thales Alenia Space: precise orbit determina- tion. Accelerometer and GPS and SLR tracking data from the German CHAMP mission were used to develop and test software eventually to be used by the GOCE ground segment. We were involved in an international comparison cam- paign, showing that at the time (2003) the most precise orbits were computed in Delft. Institute RMS Mean σ TU Delft/AS 3.60 1.31 3.36 Texas/CSR 4.43 0.04 4.42 TU Munich 4.61 1.78 4.26 Potsdam/GFZ 4.81 0.75 4.76 NASA/JPL 5.31 2.51 4.68 CNES/GRGS 6.80 3.35 5.92 NewCastle Univ 7.44 -0.59 7.42 Univ. Bern 13.56 2.55 13.33 ESA/ESOC 16.83 2.64 16.63 Colorado/UCAR 17.35 4.68 16.71 Consistency between Satellite Laser Tracking (SLR) range measurements and CHAMP orbits computed (cm). MicroNed/MISAT: relative positioning by GPS. The distance can be computed with a precision of about 0.5 mm for the US/German GRACE satellites which trail each other at a distance of about 200 km. rcv1 rcv2 gns1 gns2 gns3 gns4 gns5 KBR residuals [mm] Date in 2005 Dec 5 Dec 10 Dec 15 Dec 20 Dec 25 Dec 31 -4 -2 0 2 4 0.0+0.46 mm KBR residuals [mm] Time of day 03:00 06:00 09:00 12:00 15:00 18:00 21:00 24:00 -4 -2 0 2 4 0.0+0.44 mm ESA High-Level Processing Facility: verification of accelerometers. Non-gravitational accelera- tions, including maneuvers, can be determined at a level of a few nm/s 2 from GPS satellite tracking observations. ESA Level2 Processing System: data processing for the Swarm geomagnetic field mission. More and more low-flying satellites are being equipped with GPS receivers and ac- celerometers which measure minute atmospheric drag and solar radiation forces. We will be responsible for the precise orbit determination of the three satellites, the calibration of the accelerometers and the derivation of the neutral density and winds from the aerodynamic accelerations sensed by the accelerometers. Accelerometer satellite missions 10 -15 10 -10 10 -5 1 Density (kg/m 3 ) 0 100 200 300 400 500 600 0 100 200 300 400 500 600 0 500 1000 1500 Temperature (°C) ✈ Low solar activity High solar activity night day High activity, day Low activity, night Altitude (km) Stratosphere Mesosphere Thermosphere Troposphere Swarm C Swarm A/B GOCE GRACE A/B CHAMP TOPEX/Poseidon (Aug 1992 - Jan 2006) ENVISAT (Mar 2002 - Apr 2012) CryoSat-2 (Apr 2010 - 2015) SELENE (Sep 2007 - Jun 2009) ESA: precise orbit and gravity field determina- tion using GPS, SLR, DORIS and TDRSS obser- vations. Orbits computed with GPS, SLR or DORIS observations are consistent at the 1 cm level in the height direction. Even with the rela- tively sparse tracking by the geostationary satel- lites of the Tracking and Data Relay Satellite Sys- tem (TDRSS), a precision level of around 10 cm could be achieved for the height direction. ESA, NOAA & national funding: precise or- bit determination and altimeter data base sys- tem. The precision of the computed orbits has been improved from meter level in 1991 to cm level, significantly enhancing estimates of sea level heights. It is for example possible to iden- tify the effect of tsunami’s on sea level and the well-known climatological phenomenon El Ni ˜ no (see below). ESA: validation of precise orbit determination from SLR and DORIS observations and analysis of obser- vations from new type of altimeter. Radial orbit differences between orbit computed by CNES and Delft for 27-29 June 2010. The Root-Mean- Square is equal to 1.3 and 7.5 cm for the radial direc- tion and 3-dimensionally, respectively. This allows a clear identification of sea level varia- tions: shown are the deviations for March 2011 with respect to the long-period mean. National funding: precise orbit determination and regional gravity field recovery from DSN tracking of Lunar orbiters. Precise orbit solu- tions for Lunar Prospector data allowed a more detailed observation in the gravity field of the so- called mascons. Mare Serenitatis Old solution New solution 5˚ 5˚ 10˚ 10˚ 15˚ 15˚ 20˚ 20˚ 25˚ 25˚ 30˚ 30˚ 10˚ 10˚ 15˚ 15˚ 20˚ 20˚ 25˚ 25˚ 30˚ 30˚ 35˚ 35˚ 40˚ 40˚ -250 -200 -150 -100 -50 0 50 100 150 200 250 300 350 mgal 5˚ 5˚ 10˚ 10˚ 15˚ 15˚ 20˚ 20˚ 25˚ 25˚ 30˚ 30˚ 10˚ 10˚ 15˚ 15˚ 20˚ 20˚ 25˚ 25˚ 30˚ 30˚ 35˚ 35˚ 40˚ 40˚ -250 -200 -150 -100 -50 0 50 100 150 200 250 300 350 mgal TOPEX/Poseidon GPS TDRS BRTS DORIS SLR White Sands Faculty of Aerospace Engineering, Astrodynamics & Space missions analysis and applications Satellite orbits, mission
Transcript of ../KBRPartialFixAccelerationConstrainedPCV 05 335
Contact: dr. ir. P.N.A.M. Visser
E−mail: [email protected]
Faculty of Aerospace Engineering
Astrodynamics and Space Missions
The Astrodynamics & Space Missions group at the Faculty of Aerospace Engineering is one of the leading centers in the world forprecise orbit determination. Our group is regularly selected by the European Space Agency (ESA) to compute precise orbits for theirsatellites.
To compute our orbits we use and co-develop software from the NASA Goddard Space Flight Center and the DLR German Space Oper-ation Center. We use state-of-the-art models for density in the atmosphere and the gravity field. We maintain our own infrastructure ofservers to efficiently process the terrabytes of data coming from the satellite sensors. With our expertise and facilities we have improvedthe accury of many satellite orbits down to the cm level.
Not only do we understand the environment of the satellite, we also look at the applications of the satellites. The orbits computedby our group are used to measure ocean currents, sea level rise and in support of measuring the effect of earthquakes, for example inSumatra and Japan.
Examples of satellite missions the group has been working on include the geopotential missions CHAMP, GRACE, GOCE and Swarm,the altimeter missions TOPEX/Poseidon, ENVISAT and CryosSat-2, and the lunar mission SELENE.
CHAMP (Jul 2000 - Sep 2010) GRACE (Mar 2002 - 2019) GOCE ( Mar 2009 - 2013) Swarm (Early 2013 - 2018)
AOES/MedialabAOES Medialab
Thales Alenia Space: precise orbit determina-tion. Accelerometer and GPS and SLR trackingdata from the German CHAMP mission wereused to develop and test software eventually tobe used by the GOCE ground segment. We wereinvolved in an international comparison cam-paign, showing that at the time (2003) the mostprecise orbits were computed in Delft.
Institute RMS Mean σ
TU Delft/AS 3.60 1.31 3.36Texas/CSR 4.43 0.04 4.42TU Munich 4.61 1.78 4.26Potsdam/GFZ 4.81 0.75 4.76NASA/JPL 5.31 2.51 4.68CNES/GRGS 6.80 3.35 5.92NewCastle Univ 7.44 -0.59 7.42Univ. Bern 13.56 2.55 13.33ESA/ESOC 16.83 2.64 16.63Colorado/UCAR 17.35 4.68 16.71
Consistency between Satellite Laser Tracking(SLR) range measurements and CHAMP orbitscomputed (cm).
MicroNed/MISAT: relative positioning by GPS.
The distance can be computed with a precision
of about 0.5 mm for the US/German GRACE
satellites which trail each other at a distance of
about 200 km.
rcv1 rcv2
gns1
gns2
gns3
gns4
gns5
KB
R r
esid
ua
ls [
mm
]
Date in 2005
Dec 5 Dec 10 Dec 15 Dec 20 Dec 25 Dec 31
-4
-2
0
2
4 0.0+0.46 mm
KB
R r
esid
ua
ls [
mm
]
Time of day
03:00 06:00 09:00 12:00 15:00 18:00 21:00 24:00
-4
-2
0
2
4 0.0+0.44 mm
ESA High-Level Processing Facility: verification
of accelerometers. Non-gravitational accelera-
tions, including maneuvers, can be determined
at a level of a few nm/s2 from GPS satellite
tracking observations.
ESA Level2 Processing System: data processing for the
Swarm geomagnetic field mission. More and more low-flying
satellites are being equipped with GPS receivers and ac-
celerometers which measure minute atmospheric drag and
solar radiation forces. We will be responsible for the precise
orbit determination of the three satellites, the calibration of
the accelerometers and the derivation of the neutral density
and winds from the aerodynamic accelerations sensed by the
accelerometers.
Accelerometer
satellite missions
10 -15 10 -10 10 -5 1
Density (kg/m3)
0
100
200
300
400
500
600
0
100
200
300
400
500
600
0 500 1000 1500
Temperature (°C)
✈
Lo
w s
ola
r activity
Hig
h s
ola
r activity
night
day
High
activity,
day
Low
activity,
night
Altitude (km)
Stratosphere
Mesosphere
Thermosphere
Troposphere
Swarm C
Swarm A/B
GOCE
GRACE A/B
CHAMP
TOPEX/Poseidon (Aug 1992 - Jan 2006) ENVISAT (Mar 2002 - Apr 2012) CryoSat-2 (Apr 2010 - 2015) SELENE (Sep 2007 - Jun 2009)
ESA: precise orbit and gravity field determina-
tion using GPS, SLR, DORIS and TDRSS obser-
vations. Orbits computed with GPS, SLR or
DORIS observations are consistent at the 1 cm
level in the height direction. Even with the rela-
tively sparse tracking by the geostationary satel-
lites of the Tracking and Data Relay Satellite Sys-
tem (TDRSS), a precision level of around 10 cm
could be achieved for the height direction.
ESA, NOAA & national funding: precise or-
bit determination and altimeter data base sys-
tem. The precision of the computed orbits has
been improved from meter level in 1991 to cm
level, significantly enhancing estimates of sea
level heights. It is for example possible to iden-
tify the effect of tsunami’s on sea level and the
well-known climatological phenomenon El Nino
(see below).
ESA: validation of precise orbit determination from
SLR and DORIS observations and analysis of obser-
vations from new type of altimeter.
Radial orbit differences between orbit computed by
CNES and Delft for 27-29 June 2010. The Root-Mean-
Square is equal to 1.3 and 7.5 cm for the radial direc-
tion and 3-dimensionally, respectively.
This allows a clear identification of sea level varia-
tions: shown are the deviations for March 2011 with
respect to the long-period mean.
National funding: precise orbit determination
and regional gravity field recovery from DSN
tracking of Lunar orbiters. Precise orbit solu-
tions for Lunar Prospector data allowed a more
detailed observation in the gravity field of the so-
called mascons.
Mare Serenitatis
Old solution New solution
5˚
5˚
10˚
10˚
15˚
15˚
20˚
20˚
25˚
25˚
30˚
30˚
10˚ 10˚
15˚ 15˚
20˚ 20˚
25˚ 25˚
30˚ 30˚
35˚ 35˚
40˚ 40˚
-250 -200 -150 -100 -50 0 50 100 150 200 250 300 350
mgal
5˚
5˚
10˚
10˚
15˚
15˚
20˚
20˚
25˚
25˚
30˚
30˚
10˚ 10˚
15˚ 15˚
20˚ 20˚
25˚ 25˚
30˚ 30˚
35˚ 35˚
40˚ 40˚
-250 -200 -150 -100 -50 0 50 100 150 200 250 300 350
mgal
TOPEX/Poseidon
GPS
TDRS
BRTS DORIS SLRWhite Sands
Faculty of Aerospace Engineering, Astrodynamics & Space missions
analysis and applications
Satellite orbits, mission
