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August 16, 2008 SSPS session, URSI GA 1 Impact to the Radio Astronomy by the Interference caused by the Solar Power Satellite Systems Masatoshi Ohishi NAOJ

Impact to the Radio Astronomy by the Interference caused by the Solar Power Satellite Systems

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Impact to the Radio Astronomy by the Interference caused by the Solar Power Satellite Systems . Masatoshi Ohishi NAOJ. SSPS. Power Generation in Space (GSO) Power transmission via microwave beam Rectenna on earth ground. Pros and Cons. Can generate 24/24 No CO 2 emissions Economic - PowerPoint PPT Presentation

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Page 1: Impact to the Radio Astronomy by the Interference caused by the Solar Power Satellite Systems

August 16, 2008 SSPS session, URSI GA 1

Impact to the Radio Astronomy by the Interference caused by

the Solar Power Satellite Systems

     Masatoshi Ohishi NAOJ

Page 2: Impact to the Radio Astronomy by the Interference caused by the Solar Power Satellite Systems

SSPSPower Generation in Space (GSO)

Power transmission via microwave beam

Rectenna on earth ground

2010/06/01

Page 3: Impact to the Radio Astronomy by the Interference caused by the Solar Power Satellite Systems

IUCAF SS 2010 3

Pros and Cons

• Can generate 24/24• No CO2 emissions• Economic

> cheaper than nuclear power plant

• Unlimited energy source

• others

• Interference to radiocomm. Including RAS

• Burn out “birds”• Unknown effect to

ionosphere• Costs too much

> Sat. has life-time• others

2010/06/01

Page 4: Impact to the Radio Astronomy by the Interference caused by the Solar Power Satellite Systems

SSPS session, URSI GA 4

SSPS frequencies

• ISM band; 2.45 GHz / 5.8 GHz• Monotonic – actual bandwidth (df) ??• Harmonics may fall into the RAS bands

occupied bandwidth = n x df> 2.45GHz: x2, x6, x9, x20> 5.8 GHz: better than 2.45 GHz case> Both: 76-116 GHz

August 16, 2008

Page 5: Impact to the Radio Astronomy by the Interference caused by the Solar Power Satellite Systems

SSPS session, URSI GA 5

ISM bands/applications• 13,553-13,567 kHz, 26,957-27,283 kHz, 40.66-40.70

MHz, 902-928 MHz in Region 2, 2,400-2,500 MHz, 5,725-5,875 MHz, and 24-24.25 GHz

• RR 15.13 Administrations shall take all practicable and necessary steps to ensure that radiation from equipment used for industrial, scientific and medical applications is minimal and that, outside the bands designated for use by this equipment, radiation from such equipment is at a level that does not cause harmful interference to a radiocommunication service and, in particular, to a radionavigation or any other safety service operating in accordance with the provisions of these Regulations.August 16, 2008

Page 6: Impact to the Radio Astronomy by the Interference caused by the Solar Power Satellite Systems

SSPS session, URSI GA 6August 16, 2008

Appendix to Article 3• Tables of maximum permitted power levels for

spurious or spurious domain emissions

• Attenuation (dB) below the power supplied to the antenna transmission line:43 + 10 log (P), or 70 dBc, whichever is less stringentP = 1GW = 109W 43 + 10 log (P) = 943 > 70 100 W such power may burn out RAS Rx !

Page 7: Impact to the Radio Astronomy by the Interference caused by the Solar Power Satellite Systems

SSPS session, URSI GA 7

Spectral purity

• The bandwidth for the transmission (df) must be as narrow as possible to avoid interference detrimental to the RAS.

• The harmonics/intermodulations must be suppressed in order not to cause unacceptable interference to the RAS.

August 16, 2008

Page 8: Impact to the Radio Astronomy by the Interference caused by the Solar Power Satellite Systems

SSPS session, URSI GA 8

Detrimental thresholds for total power observations

0.01 0.1 1 10 100 1 103

260

240

220

200

180

Frequency GHz

SPFD

[dB

W /(

m^2

.Hz)

] Black: continuum Red: spectral line

Recommendation ITU-R RA.769August 16, 2008

Page 9: Impact to the Radio Astronomy by the Interference caused by the Solar Power Satellite Systems

SSPS session, URSI GA 9

Extremely low far sidelobe• The sidelobe of the

transmitting antenna must also be as low as possible to avoid serious damage to the RAS antenna.

df=1MHz(?)peak: ~30mW/cm2

-35dBW/m2/Hz1st SD: 0.1mw/cm2

-60dBW/m2/HzAugust 16, 2008

RA.769spfd = (-250 ~ -230) dBW/m2/Hz

Page 10: Impact to the Radio Astronomy by the Interference caused by the Solar Power Satellite Systems

SSPS session, URSI GA 10

Sky occupied by SSPSs

• 1GW / satellite• 1 TW (or more) 1000 satellites• GSO – every 2 degrees

360/2 = 180 satellites 1000 - 180 = 820 satellites are not in the GSO NGSO (HEO ?)

August 16, 2008

Page 11: Impact to the Radio Astronomy by the Interference caused by the Solar Power Satellite Systems

SSPS session, URSI GA 11August 16, 2008

Interference by GSOs

GSOs

21cm obs. at Bonn

Page 12: Impact to the Radio Astronomy by the Interference caused by the Solar Power Satellite Systems

SSPS session, URSI GA 12

Projection of the geostationary orbit onto the celestial sphere as seen from a number of radio observatories

RA Handbook Fig. 4.3 (p. 45)

August 16, 2008

Page 13: Impact to the Radio Astronomy by the Interference caused by the Solar Power Satellite Systems

SSPS session, URSI GA 13

Other orbits than GSO ?Highly Elliptical Orbit (HEO) Satellite

Projected orbit

August 16, 2008

Too many spotson the sky !

Page 14: Impact to the Radio Astronomy by the Interference caused by the Solar Power Satellite Systems

SSPS session, URSI GA 14

Interference to optial/IR astronomy• 10x10 km2 solar cell

~ 1 arcmins larger than Jupiter (~40 arcsecs)permanent blocking

• Reflection of the solar light

August 16, 2008

Page 15: Impact to the Radio Astronomy by the Interference caused by the Solar Power Satellite Systems

SSPS session, URSI GA 15

Summary

• SSPSs may cause interference detrimental to the radio/IR/optical astronomy.

• Spectrum purity, very low sidelobe are crucial to minimize the problems.

August 16, 2008

NY times July 23, 2008

?