alexander p. trishchenko - wmo.int · alexander p. trishchenko. 2/18 gscis-ep-12. june 1, 2012...

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GSCIS-EP-12. June 1, 2012

HEO, LEO, GEO and GSICS

Alexander P. Trishchenko

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Outline

HEO concept to continuously observe the Arctic• Objectives and history• Radiation environment• Orbital issues

HEO-GEO intercalibrationHEO-LEO intercalibration Summary

HEO HEO -- HHighly ighly EElliptical lliptical OOrbitrbitPCW PCW –– Polar Communication and Weather, Polar Communication and Weather,

Canadian HEO projectCanadian HEO project

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GSCIS-EP-12. June 1, 2012LEO temporal coverage

tt

t

tt

t

tt

t

Swath

tihNN

sincos),(~

]sin)1arcsin[(

)(),(~ 5.12

E

E

RhGM

hRhN

Number of satellites N to achieve refresh rate tat latitude circle

where

h - orbit altitudeβ – max scan angleRE – Earth radiusGM – gravitational constanti – orbit inclination

Image from LEO system is obtained as a result of orbital motion and cross-track scanning

Trishchenko & Garand, CJRS, 2012.

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HEO goal - continuous Arctic coverage

2 satellite HEO system can provide continuous coverage above 600N with VZA <700

• 23(34) LEO (JPSS-like) satellites would be needed to achieve 15(10)-min image refresh rate at 600N,

Trishchenko et al, JTECH, 2011

Zonal mean 2-sat HEO coverage

100% (i.e. continuous coverage) above 600N can be achieved from 2-sat HEO system

at 60o latitudet Number of sats

20 min - 17 LEO satellites15 min - 23 LEO satellites10 min - 34 LEO satellites

5 min - 68 LEO satellites

LEO satellite orbits are similar to NOAA/JPSS

Trishchenko & Garand, CJRS, 2012.

# of LEO satellites as function of

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Molniya (12-h) orbit is a popular HEO choiceHarsh ionizing radiation is Molniya’s orbit biggest challengeHow can we solve the radiation problem without affecting HEO goals ?

High energy trapped protons with E>10Mev are the most dangerousTrishchenko et al, JTECH, 2011

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Requirements (orbit optimization criteria)1) Arctic Coverage with 2-sat system:

• 100% above 600N• >95% above 550N• >80% above 500N

2) Radiation Environment• Avoid trapped energetic protons (>10Mev for

sure, but as much as possible)• As close as possible to GEO• In any circumstance, PCW is a subject to solar

and cosmic particles due to open magnetic lines in the polar region

3) Spatial resolution or altitude range: • Apogee <45,000 km – to maintain reasonable

spatial resolution (25% worse than GEO case)4) Orbit maintenance

• Stay close to critical inclination to minimize perigee rotation and orbit maintenance

5) Reception from 1 satellite station is desirable

• Yellowknife: 62.4422220N, -114.39750E 6) Small ground speed during imaging period – desirable feature

z

Earth’s spin axis

Perigee

Apogee

Equatorial plane

x

y

Ascending node

Vernal equinox

i

H a=a(1

+e)

H p=a(1

-e)

Descending node

O

l

z

Earth’s spin axis

Perigee

Apogee

Equatorial plane

x

y

Ascending node

Vernal equinox

i

H a=a(1

+e)

H p=a(1

-e)

Descending node

O

l Semi-latus rectum

z

Earth’s spin axis

Perigee

Apogee

Equatorial plane

x

y

Ascending node

Vernal equinox

i

H a=a(1

+e)

H p=a(1

-e)

Descending node

O

l

z

Earth’s spin axis

Perigee

Apogee

Equatorial plane

x

y

Ascending node

Vernal equinox

i

H a=a(1

+e)

H p=a(1

-e)

Descending node

O

l Semi-latus rectum

Rate of change for the argument of perigee


22

22

21

1cos543

ei

arnJ E

22

22

21

1cos543

ei

arnJ E

Altitude distribution of protons at equator

=0, when i=63.40 - critical inclination.

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HEO orbit optimization

TAP (16-h)Apogee: 43,500 km

Radiation limit

Spatial resolution limitThree Apogee - TAP16-h HEO (e=0.55)as optimal choice


Molniya 12-h

Tundra 24-h

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Orbit comparison (2-sat constellation)

Molniya (12-h)Apogee: 39,800 km

Tundra (24-h)Apogee: 48,300 km

TAP (16-h)Apogee: 43,500 km

950W

50W

1750

E

850E

±4hrs

Yellowknife

950W

50W

1750

E

850E

±4hrs

Yellowknife

±5hrs

Yk

950W

250 E

1450E

±5hrs

Yk

950W

250 E

1450E

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16 hr/day of imaging per satellite

Data reception at Yellowknife

Comparison of zonal mean spatial coverage

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Satellite altitude for various orbits

Height at 40 N (central US)

TAP: 30,000 kmMolniya: 19,500 km24-h: 41,200 km

For TAP 95 W apogee path, data reception at Yellowknife starts at about 33 N(height of ~27,000 km, 5.3 h to apogee)

For Molniya, reception starts atAbout 45 N (H= ~22,500 km)4.0 h to apogee

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0h

2h4h

6h

14.50

15.3017.90

26.20

Earth views from TAP orbit

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Some GEO and HEO (TAP 16-h)

Shaded areas show collocation between GEO and HEOVZA<50; RAZ<100

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Some GEO and Molniya (12-h)

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NPP/Suomi and HEO/TAP(16-h)

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NPP/Suomi and HEO/Molniya (12-h)

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Matching pairs TAP & NPP

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Temporal sequence of matching pairsTAP & NPP

Collocations between HEO and NPP can happen every day

VZA<50, RAZ<100

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ConclusionsPCW 2-satellite HEO system is significantly more efficient for observing Polar Regions than constellation of LEO polar orbiters;17/23/34/68 LEO satellites are required at 600N to provide an imagery updated every 20/15/10/5 min, respectively. Corresponding numbers in the vicinity of the North Pole are 5, 7, 10 and 20.Unique quasi-geostationary capability of HEO system over polar latitudes provides good opportunity for satellite intercalibration with polar orbiters and some opportunities with GEO.

ReferencesTrishchenko, A.P., L.Garand, L.D.Trichtchenko, 2011: Three apogee 16-h highly elliptical orbit as optimal choice for continuous meteorological imaging of Polar Regions. Journal of Atmospheric and Oceanic Technology. Vol. 28(11), pp. 1407-1422.Trishchenko, A.P., and L. Garand, 2011. Spatial and temporal sampling of Polar Regions from two-satellite system on Molniya orbit. Journal of Atmospheric and Oceanic Technology, Vol. 28(8), pp. 977-992.Trishchenko, A.P. and L.Garand, 2012: Observing Polar Regions from space: Advantages of a satellite system on a highly elliptical orbit versus a constellation of low Earth polar orbiters. Canadian Journal of Remote Sensing. Vol. 38, No. 1, pp. 12-24.

Acknowledgements

Contributions from Louis Garand (EC) and PCW team are gratefully acknowledged.SPENVIS tool was used for space environment radiation analysisMODIS “blue-marble” imagery was used in simulations

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