Infrared Laser Satellite- Aircraft Communication

Paul ChristopherPFC AssociatesLeesburg, VA

pfchristopher56@gmail.com

NAECON 2018 pc

Satellite-Aircraft Laser Communication

• Chu and Hogg laser attenuation vs wavelength• Cloud attenuation from Barbaliscia’s Italsat

Solve -22.2 GHz attenuation maps-and 49.5 GHz attenuation maps for

cloud att’n, and water vapor att’n• Show worldwide satellite- ground 10 micron att’n• Show satellite – aircraft 10 micron att’n

- other IR wavelengths

NAECON 2018 pc

Chu & Hogg’s Attenuation v. Frequency, GHz

500. 1000. 5000. 10000. 50000. 100000.

Rain and Heavy Fog Att'n vs. Log(fGHz)

2

5

10.

20.

50.

100.

200.

dB10u

fog

rain

F,GHz

Fig. 3-1 Chu and Hogg’s Fog(top) and Rain Attenuation(dB) v. FrequencyNote, 10u at 30,000 GHz and 1u at 300,000 GHz

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Massive 10 Micron Attenuation for Ground-Satellite

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Ground Attenuation Relief with Quad Diversity, 100 km

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Satellite-Aircraft Att’n; 1,2,3 km Altitude

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10 Micron Attenuation over N. America (2015) with 30% Cloud Cover

Thule

dB

. A 30% cloudless sky was assumed.a. 100 km Quad diversity b. 200 km c. 300 km

Fig 1-1 Zenith Attenuation Estimates for Quad Diversity over North America 80% Reliability

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Clear Sky Estimates for U.S as Function

With Sunny Days=

Mathematica Feb15—80pc90pc.nb

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Att’n at 80% Availability, 10 Microns

Fig. 1-3 Ten Micron Zenith Attenuation (dB) Estimate for U.S., 80% Availability

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Higher Reliability with 10 Micron Links

These conservative attenuation estimates are expected to offer even lower attenuation with closer estimation.

Out[405]= , ,

80% Diversity, 200 km on a side

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Aircraft [2km]- Satellite 10Micron Att’n

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Low Att’n Aircraft[3km]-Satellite, 10 Microns

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Satellite-Aircraft Att’n; 1,2,3 km Altitude

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Aircraft- Satellite Att’n at 0.5 km Increments

6 Micron Att’n at ½ km increments

3 u Att’n at 0.5 km Increments

Ju Fig. 2-1 Compare Functional Estimates for Clear Atmosphere over the U.S and Europe

Compare Clear Skies in U.S., Europe

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Concluding Thoughts

• Satellite-Ground laser communication may be attractive

-if modest 80% availability-if large scale ground diversity, as Takayama

• Satellite- Aircraft laser comm is attractive-for altitude>2km

--both 10u, and 6u-especially on polar routes

--with LEOS or Brandon Molniya

NAECON 2018 pc

New Developments, Solar Impulse Flight Across U.S., Around World

• Bertrand Piccard and Swiss Research recognized Solar Power.

• They realized Solar Cells on the wing would offer good power.

• Strong, Rigid Wing• Carbon Fiber Frame• Wing Span like 747• Electric motors deliver 10 hp• Piccard concepts will be attractive for Satellite Solar

Arrays

AFM 2015 pc

Gerard O’Neill’s Solar Satellite Array Concept

• O’Neill’s offered many satellite concepts in the mid ‘70s• His book High Frontier(‘77) is available• Large solar panels on Geosynchronous satellites• Beam 2.2 GHz radio energy down to Large Ground

receiver.• Support faded when gas dropped, Ground Arrays limited.• O’Neill’s health declined in the early ’80s

- A National Loss- and a NASA Loss

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Would Satellite Solar Arrays Be Competitive?

• Warren Buffett investing 1.9 B in 656 wind turbines in Iowa.• Would add 1050 megawatts power by 2015.• May be interesting comparison for satellite solar arrays.

-e.g., 1km square array => 1300 MW solar input- if 30% efficiency => 400 MW to Denver

• German research in satellite solar arrays- Expect test satellite launch by 2016.

• Jalali solid state silicon lasers promise reliable link to Ground- 10 micron solid state lasers appear feasible- Low atmospheric loss

NAECON 2018 pc

Perovskite Complement to Jalali’sSilicon Laser [Sci Am, July 2015]

Attractive Satellite Orbits for Solar Arrays

• Gerard O’Neill favored Geostationary orbits-Stationary ground antennas for low cost

• Low Altitude, sun synchronous satellites-Perhaps (1/10) cost of Geostationary satellites-Solar Panels are perpendicular to Sun Vector-Active, difficult ground pointing.

• Brandon Molniya Orbits;GoodDownlinks to Denver,North-retains easy ground station pointing of Geos.

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Geosynchronous Arc for Wide Range of DownlinksMathematica Apr24GEO1.nb

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Solar Array at GEO; Power Density on US, with 10m geo antenna at 3 GHz [as S Band]

Mathematica Apr21—JiuxB.nb

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Power Density with 30 GHz, 10m Antenna at GEO

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Sun Synchronous Orbits for Cost Effective Solar Arrays

EOS at 1200kmDebris Field at 800kmDebris Field

A Chinese anti-satellite test in January 2007 left an enlarged debris field between centered near 800 km altitude. It stretches from 700 km to over 900 km altitud

Fig. 2-1 ASAT Debris Field, Fig. 2-2 EOS Higher (1000km) thanMean Altitude 800 km . Debris Field

Mathematica Apr27—EOScx.nb .NAECON 2018 pc

Sun Synchronous View at 701 kmInclination= 98.4 Deg.

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Emphasize the Late W.T. Brandon’s Concepts

• W.T. (Bill) Brandon observed key Molniya Features the 1970’s• Noted excellent N Hemisphere visibility• But Difficult/Expensive 3D Ground Tracking• Bill observed key changes in Ease of Tracking(eccentricity)• Sudden changes in tracking for .71< e < .73• E=0.722 for High Gain, single rotation axis antenna• E=0.722+ for High Gain, stationary antenna• E=0.729 for Higher Gain, stationary antenna• First, Bill was fascinated with Molniya Earth Views:

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Brandon Molniya Valuable for Northern Hemisphere

Brandon Molniya 1 Hr Snaps Three Molniya Ground View

Molniya at 1 hr Intervals

Molniya seen from Ground Station

Mathematica July508—C3.nb

AFM 2015 pc

Compare 3D Views of Molniya; e=.64, .722Compare e.722, .64; Molniya seen from Ground Station

e=.7222 Hr,10Hr

e=.648 Hr10 Hr

e=.7226 Hr

e=.72218 Hr

AFM 2015 pc

Elevation PDF for Brandon4 Constellation+ 2 Antipodal GEOs

pE,Lat;4Brandon Molniya 2 Geo sats.

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20

40

60

LAT

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60

80

El

0

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pdf0

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AFM 2015 pc

P ( E ) for Brandon4 Constellation

searched exhaustively for elevation angles at all time and locations to yield a probability density function as:pdf [elev, LAT]=

( 2 -1)where LAT =latitude

x=elevation

AFM 2015 pc

Sunspots and Temperature