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Institute of Applied Astronomy Russian Academy of Sciences

Planned LLR station in Russia and its impact on the Lunar Ephemeris Accuracy
M.V. Vasilyev(1), E.I. Yagudina (1), Jean-Marie Torre(2), Dominique Feraudy (2) (1) Institute of Applied Astronomy, Saint-Petersburg, Russia (2) Universite de Nice Sophia-Antipolis CNRS UMR 7329 OCA Geoazur Caussols, France.

22-24 September 2014,Journees 2014,Planned LLR station in Russia and its impact on the Lunar Ephemeris Accuracy © Yagudina et all.


INTRODUCTION
· Precise modern Lunar Ephemerides (DE/LE, INPOP, EPM-ERA) are based on only LLR observations obtained at several LLR ground stations during 1969 ­ 2013 years: LLR station Time interval Obs.number

McDonald MLRS1
MLRS2 HALEAKALA CERGA APACHE Total ·

1970 March-1985 June 1985 Jan-1988 January
1988 August-2012 April 1988 August-1990 August 1985 Jan-2013 February 2006 July-2012 August 1970 March-2013 February

3440 275
3114 694 9599 1576 18700

There are two projects of new LLR stations:

Altay(Russia) and La Silla(Europe) stations.

Expected impact of new Russian LLR station on the Lunar ephemeris accuracy is the main topic of the presentation.
22-24 September 2014,Journees 2014,Planned LLR station in Russia and its impact on the Lunar Ephemeris Accuracy © Yagudina et all.


Altay LLR station
1. Location: Siberia, Altay Optical-Laser Center, approximate coordinates are (51°N, 82°E, 385 m). 2. 3.12 meter telescope (Altay Optical-Laser Center) as probable base telescope for the LLR station 3. Target accuracy of LLR observations (normal point) is about 3mm 4. Meteorological conditions: 1400 clear night hours, 240 nights suitable for LLR observation per year 5. Major project participants: OJC «Research-and-Production Corporation «Precision Systems and Instruments», VNIIFTRI and IAA RAS

Motivation and methods are presented below: · To check the urgency of the project it should be shown in particular that the accuracy of the lunar ephemeris will visibly increase · The only way to prove that fact now is the numerical simulation

22-24 September 2014,Journees 2014,Planned LLR station in Russia and its impact on the Lunar Ephemeris Accuracy © Yagudina et all.


Numerical simulation
1. Distribution of real LLR observations (18700) at interval 1970 -2013 have been analyzed depending on LLR station: · Target reflectors distribution · Elevation distribution · Observations per day distribution · Etc
Reflectors distribution
70 60 50 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0

Elevation distribution

2.5 2 1.5 1 0.5 0

Observations number per day

%

40 30 20 10 0 L1 Apollo11 Apollo14 Apollo15 L2

%

%

1

11

21

31

41

51

61

71

81

1 4 7 10 13 16 19 22 25 28 31 34 37

Degrees

Observations number

2. Due to complexity and irregularity of the distributions above it was decided that observation programs of real LLR stations will be used for numerical simulations 3. Observation programs of Apache and Cerga stations have been chosen as the basis to create simulated LLR measurements 4. Special SW was developed for simulation: · LLR observations simulation for Altay station · Adjusted parameters estimation using both real and simulated LLR measurements
22-24 September 2014,Journees 2014,Planned LLR station in Russia and its impact on the Lunar Ephemeris Accuracy © Yagudina et all.


Numerical simulation: scenarios

I.1.18700 real observations (1970-2013 years) + simulated observations from 2006 till 2013 at Altay station like it was observed at Apache (Apollo) or Cerga station. (in simulation-"Apache 2006", "Cerga2006"). I.2. 18700 real observations (1970-2013 years) + simulated observations from 2006 (1 month shift) till 2013 at Altay station like it was observed at Apache (Apollo) or Cerga station. (in simulation-"Apache 2006shift", "Cerga2006shift"). II. 18700 real observations (1970-2013 years) + simulated observations from 2008 till 2013 at Altay station like it was observed at Apache (Apollo) or Cerga station. (in simulation-"Apache 2008", "Cerga2008"). III. 18700 real observations (1970-2013 years) + simulated observations from 2012 till 2013 at Altay station like it was observed at Apache (Apollo) or Cerga station. (in simulation-"Apache 2012", "Cerga2012").

22-24 September 2014,Journees 2014,Planned LLR station in Russia and its impact on the Lunar Ephemeris Accuracy © Yagudina et all.


Simulation results
Impact on parameter's accuracy: "Apache 2006" and "Cerga2006" scenarios
20 18 16 14 12 10 8 6 4 2 0 1 6 11 16 21 26 31 36 41 46 51 56 61 66

%

Apache Cerga

Adjusted parameters
N 1 2 3 4 5 6 7 8 Parameter X Y Z Vx Vy Moon Moon Moon Moon Moon N 15 16 17 18 19 20 21 22 Parameter N 29 30 31 32 33 34 35 Parameter N 42 43 44 45 46 47 48 49 Parameter N 55 56 57 58 59 60 61 62 Parameter

Vz Moon Libration Libration

A11 PY A14 long A14 PX A14 PY L2 long L2 PX L2 PY

CERGA PX CERGA long CERGA PY Halaek PX Halaek long Halaek PY MLRS1 PX



9
10 11 12 13 14

Libration
Libration d/dt Libration d/dt Libration d/dt

23
24 25 26 27 28

A11 long A11 PX 22-24 September 2014,Journees

36 A15 PX MLRS1 long 37 MCD PX MLRS1 PY 38 MCD long Apache px 39 MCD PY Apache long 40 MLRS PX Apache py 41 MLRS long Lag Earth MLRS PY 2014,Planned LLR station in Russia and its impact

C20 C21 S21 C22 S22 C30 C31 S31 C32 S32 C33 S33 T*sidt

T*sidt Moon T*deps T*dpsi deps dpsi Lag Moon k2 Moon A15 long A15 PX A15 Py L1 long L1 PX L1 PY

50
51 52 53 54

63
64 65 66 67

on the Lunar Ephemeris Accuracy © Yagudina et all.


Impact on the Lunar ephemeris accuracy "Apache 2006" and "Cerga2006" scenarios
12

10

8

%

6 Apache Cerga 4

2

0 1 2 3 4 5 6 7 8 9 10 11 12

Adjusted parameters: initial Lunar state vector and libration angles
22-24 September 2014,Journees 2014,Planned LLR station in Russia and its impact on the Lunar Ephemeris Accuracy © Yagudina et all.


Accuracy vs observation interval
Lag of the Moon
6 5 4 6 5 4 Apache Cerga

Lag of the Earth

%

3 2 1 0 0 2 4 6 ) 8

%

3 2 1 0 0 2 4 6 ) 8

Apache Cerga

Observation interval (years

Observation interval (years

K2 Moon
16 14 12 10 9 8 7 6 5 4 3 2 1 0 0 2

Mo o n Z

10

%

8 6 4 2 0 0 2 4 6 ) 8

Apache Cerga

%

Apache Cerga

4

6 )

8

Observation interval (years

Observation interval (years

22-24 September 2014,Journees 2014,Planned LLR station in Russia and its impact on the Lunar Ephemeris Accuracy © Yagudina et all.


La Silla LLR station 1. SHELLI (Southern Hemisphere Lunar Laser Instrument) project, location: ESO, La Silla, Chile (29°S, 70°W, 2400m) 2. NTT telescope (3.6 meter) as proposed base telescope for the LLR station 3. As a twin of Apache Point in terms of quality and regularity of the produced data 4. Meteorological conditions: ESO, bordering the southern extremity of the Atacama desert in Chile 5. Probable project participants: ESO, Geoazur (OCA), INSU

22-24 September 2014,Journees 2014,Planned LLR station in Russia and its impact on the Lunar Ephemeris Accuracy © Yagudina et all.


Altay vs La Silla station
Altay station: "Apache 2006" and "Cerga2006" scenarios
25 20 15

%

10 5 0 1 6 11 16 21 26 31 36 41 46 51 56 61 66

Apache Cerga

Adjusted parameters
La Silla station: "Apache 2006" and "Cerga2006" scenarios
25 20 15

%

10 5

Apache Cerga

0
1 6 11 16 21 26 31 36 41 46 51 56 61 66

Adjusted parameters
22-24 September 2014,Journees 2014,Planned LLR station in Russia and its impact on the Lunar Ephemeris Accuracy © Yagudina et all.


Altay vs La Silla station
Altay station: "Apache 2006" and "Cerga2006" scenarios
20 18 16 14 12

%

10 8

Apache Cerga

6
4 2 0 1 2 3 4 5 6 7 8 9 10 11 12

Adjusted parameters: initial Lunar state vector and libration angles

La Silla station: "Apache 2006" and "Cerga2006" scenarios
20 18 16 14 12

%

10 8 6 4 2 0 1 2 3 4 5 6 7 8 9 10 11 12

Apache Cerga

Adjusted parameters: initial Lunar state vector and libration angles
22-24 September 2014,Journees 2014,Planned LLR station in Russia and its impact on the Lunar Ephemeris Accuracy © Yagudina et all.


Observation conditions: latitude dependence Elevation of the Moon: Apache, Cerga, Altay
90 80 70 60 50 40

Elevation (degrees

30 20 10 0 -10 -20 -30 Apache

)

Cerga
Altay

-40
-50 -60 -70

-80
-90

Every 30 min during 0.5 year(2014)

22-24 September 2014,Journees 2014,Planned LLR station in Russia and its impact on the Lunar Ephemeris Accuracy © Yagudina et all.


LLR observations: geography

22-24 September 2014,Journees 2014,Planned LLR station in Russia and its impact on the Lunar Ephemeris Accuracy © Yagudina et all.


Conclusions

· According our simulations new Russian LLR observations will provide visible accuracy improvement of the Lunar ephemeris and corresponding physical models: about 2-16% depending on the adjusted parameter.

· Simulation SW was developed estimating the impact of new LLR stations on the accuracy of Lunar ephemeris.
· Russian LLR station (Altay) has observational limitation due to geographical position. So, its observation program should be very intensive to provide the impact comparable with other modern LLR stations.

· The received result are in good agreement with analogous works (for example, the paper French colleagues about proposal of installation LLR device at 3.6 m telescope in Southern Hemisphere, La Silla). · Russian LLR station can give contribution into the common world database of LLR observations.
22-24 September 2014,Journees 2014,Planned LLR station in Russia and its impact on the Lunar Ephemeris Accuracy © Yagudina et all.


Thank you for attention

22-24 September 2014,Journees 2014,Planned LLR station in Russia and its impact on the Lunar Ephemeris Accuracy © Yagudina et all.