The Netherlands China Low Frequency Explorer (NCLE) on Change'-4 by Linjie Chen

1. The Netherlands-China Low
Frequency Explorer (NCLE)
Linjie Chen / 陈林杰
on behalf of the NCLE scientific teams
National Astronomical Observatories, Chinese Academy of Sciences

2. Outline
• Background
• Scientific objectives
• NCLE Designs & Developments
• Summary

3. Chinese Lunar Exploration Program

4. Chang’E-4 Mission

5. NCLE Beginning
NCLE Cooperation Agreement was signed on Jan. 18, 2016 between
Chinese and Dutch teams

6. Opening the Last Unexplored Frequency Regime
Wavelength
Total
Atmosphere
absorption
Partial
Atmosphere
absorption
Total
Ionosphere
aborption
γ ray X-ray UV Visible IR microwave meterwave VLF/ULW
Must go to space to observe
Astronomical Exploration of the Electromagnetic Spectrum

7. NCLE science Objectives
RFI Characterization
AKR, QTN Characterisation
Constraining Dark Ages/Cosmic Dawn
Galactic Background Spectrum
Low-Frequency Sky Map
Solar Burst
Priority
Radio Transients, Crab
like pulses
Frequency100 kHz80 kHz 1 MHz 10 MHz 30 MHz 50 MHz 80 MHz
Technical Objective
Science Objective
VLBI with Earth-based, Lunar-based and Space-based facilities
Science potential
Planetary Science
(Jupiter/Saturn Emission)
Planetary Science (Jovian
S Burst & DAM)

8. Design Baseline
Frequency Band 0.08-80MHz
Antenna 3 orthogonal
monopoles
Power <50 W
Mass <10kg
Dimension 350 x 350 x 200 mm
Life time 3 year

9. NCLE Sensitivity
Sensitivity of the NCLE antenna for the integration time of 1 second, 1 day and
11 days with a LNA noise 230 K and frequency band of 10 KHz.

10. NCLE Sensitivity (3 bands)
(2nd Nyquist)<3 MHz 60-80 MHz1-60 MHz
Within 2 dB of
measured
sensitivity
Main science
band

11. NCLE Schematic
Diagram Outside Platform
Inside Platform

12. NCLE Antenna Deployment Test

13. NCLE Inside Instruments
PSU
CDHS
OCXO
DRS
AIS & Cali
E-Box LNA
Box

14. NCLE components
• Three Monopoles, 5m each
• 3 bands: <3 MHz, 1-60 MHz, 60-80 MHz
• 16k chan, 7.5-0.9kHz, 100 ms dump time
• Sky noise limited for 2-50 MHz
• Full polarization: XX, YY, ZZ, XY,XZ,YZ
• 14 bit ADC: 4x, 120 MHz
• on-board memory: 250 GB
• Downlink: < 10Mbps
• Power: < 25W
• Mass: < 10Kg
Digital Receiver & Control
Low Noise Amplifier
Antennas

15. Signal Processing and Scientific Mode

16. Overview of tests on NCLE FM
Summary of results - functional tests performed before, during and after
Ambient Thermal test EMC test - radiated emission Vibration test
Subsystems 3 cycles, FM 2 cycles
(-45o to +60o)
Levels below CE4R requirement
and MIL-STD461E Random & Sine vibration
TVAC test
1 non-operational (-450 to +600) and 2
operational (-250, -100 to +600) cycles
End-to-End
Linear and sensitive (sky-background limited) system!

17. NCLE Test Before Integration with Relay
Satellite
System Test at NSSC in March, 2018

18. NCLE arrived at L2 halo orbit
Now the lunar lander of CE-4 is going to be launched. After that, NCLE will be
switched on for the preliminary observations.
NCLE was launched on May 21, 2018 NCLE arrived at L2 orbit on Jun. 13, 2018

19. Summary
• NCLE is a pathfinder instrument onboard Chang’E 4 mission,
and also a technical demonstrator for the future space VLF
radio telescope. It aims to open up the last unexplored radio
regime, and has been launched in 2018 .
• NCLE will map the sky at very low frequency; detect the
planetary radio emission; observe the solar radio burst.
Technically, it will also characterize the Earth’s RFI and AKR,
measure the galactic background.
• NCLE will try to study some potential sciences like Dark-ages
21cm emission, VLBI observations with Moon-Earth baseline.
Thanks for your attention!