NAPEOS: The ESA/ESOC Tool for
Space Geodesy
Tim Springer, Florian Dilssner, Diego Escobar,
Drazen Svehla, Claudia Flohrer, Rene Zandbergen
EGU 2011, Vienna, Austria
07/04/2011
NAPEOS Facts (1)
– ESOC Navigation Support Office does all its operational work with
NAPEOS
– ESOC uses NAPEOS operational for three space geodetic techniques
–
GNSS, DORIS, SLR
– ESOC is a full analysis centre in the three technique services
–
IDS, ILRS, and IGS
–
Performance is excellent in all three services
– ESOC contributed significantly to the ITRF2008 by participating in
the reprocessing of all three techniques
NAPEOS is very well suited for analysing the data from
all three space geodetic techniques
Excellent Performance in IGS
Excellent Performance in ILRS
Source of plot: Cecilia Sciarretta based on weekly ILRS combination
NAPEOS Facts (2)
– NAPEOS has been used extensively for GNSS LEO data
–
JASON-1/2 complete time frame from 2001-2011
– High accuracy LEO orbits
–
Using ESOC IGS reprocessing with 30 second clocks
–
PPP-like solution for JASON-1 and JASON-2
–
Reference: Paper by Claudia Flohrer et al. in “Advances in
Space Research”
– GNSS PCVs for LEO processing based on combined GNSS solution
–
JASON-1/2 + 100 IGS stations as “normal” IGS solution
–
No external reference frame needed to derive z-PCOs!
–
Reference: Poster by Florian Dilssner at EGU 2011
–
Resulting PCV product: ideal for LEO GNSS processing
NAPEOS can efficiently and accurately handle GNSS LEO data
Excellent quality of LEO orbits
NAPEOS Facts (3)
– NAPEOS is used in the “Combination at the Observation Level”
project of the IERS
–
–
Provided 3 different solutions:
–
GNSS + SLR (IGS-like + SLR of the GNSS sats.)
–
DORIS + SLR (IDS-like + SLR of the DORIS sats.)
–
SLR only solution (LAGEOS 1/2, ETALON 1/2)
Description: ftp://dgn6.esoc.esa.int/cool/000readme.cool
–
–
Reference: COL-WG poster here at the EGU 2011
Next steps:
–
Adding JASON GNSS data to “GNSS + SLR” solution
–
Combination of the 3 solutions on NEQ level
NAPEOS is capable of combining the observations from all three
space geodetic techniques on the observation level
Mean and RMS of SLR O-C Analysis (mm)
Observed – Computed Statistics of
SLR observations from GNSS Satellites
50
5000
40
4000
30
3000
20
2000
10
1000
0
GPS-35
GPS-36
GLO-729
GLO-723
GLO-716
GLO-714
GLO-713
0
-10
-20
-1000
-30
-2000
Mean
RMS
#Obs
Small bias and small RMS for GNSS satellites
Combination of the techniques is feasible
Document title | Author Name | Place | Data doc | Programme | Pag. 8
Main Goals with NAPEOS at ESOC
– Connect the three space geodetic techniques on the observation
level which has as advantages (compared to ITRF 2008 realization):
– It makes full use of the common parameters
– E.g. GNSS and JASON orbit parameters
– We can introduce JASON-1 and JASON-2 for SLR and GPS
solutions (for ITRF only IDS made use of this satellites)
– Connect the techniques in space (“space-ties”) using the
local ties between the on-board instruments (but also using
the local site-ties on the ground)
– Main differences compared to ITRF 2008 realization:
– Includes SLR observations from the GNSS targets
– Includes GNSS and SLR observations from JASON-1 and -2
– Uses “space-ties” and local ties but will lack VLBI data
Summary and Conclusions
– Combination of GNSS, SLR and DORIS will allow
– Determination of “unified” reference frame
– Absolute estimation of GNSS satellite antenna offsets
– Already possible with just GNSS when including a LEO
like JASON
– Absolute estimation of SLR station biases (where needed)
– Definitely needed for some sites. Combination also
makes it easier to detect the biases
– Determine the orbits of all satellites in the unified reference
frame
– NAPEOS is the unique tool that is capable of doing this
THANK YOU
Tim Springer and Florian Dilssner
Tim.Springer@esa.int
Florian.Dilssner@esa.int