space platforms

7/23/2019 Space Platforms

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EN OR PLATFORM U ED IN REMOTE EN ING:

INTRODUCTION:A platform is the vehicle or carrier for remote sensors for which they are borne

In Meteorology platforms are used to house sensors which are obtain data for remote sensing purposes, and are classified according to their heights and events to be monitored.

In this paper we are going to discuss the various types of platforms their advantages and

disadvantages.

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PLATFORMS USED FOR REMOTE SENSING:

A platform is the vehicle or carrier for remote sensors for which they are borneThey are classified into three categories.

• Ground8based

• Airborne

• pace8borne

Ground-Based Plator!s

Mo"#le $%draul#& Plator!s

• 2arried on vehicles

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• E9tendable to a height of 1)m above the surface.

• At the top of the platform there are: pectral reflectance meters

;hotographic systems

I or Microwave scanners

• in<ed to data loggers in the vans.

L#!#tat#on: vehicles limited to roads, and the range is confined to small area

along or around the road.

Porta"le Masts

• !sed to support cameras and scannersE.g. a and over fitted with an e9tending aerial

• imitation: very unstable in windy conditions.

To(ers

• 2an be dismantled and moved from one place to another.

• +ffer greater rigidity than masts but are less mobile and re=uire more time to erect.

)



*eat+er Sur,e#llan&e Radar

• A #eather urveillance adar is of the long range type which detects and trac<s typhoons

and cloud masses at distance of 0%% <ilometers or less.

• This radar has a rotating antenna dis< preferably mounted on top of a building free from

any physical obstruction.

http://upload.wikimedia.org/wikipedia/commons/a/aa/Darwin_Ap_WF3_Radar.jpg



• adio energy emitted by the transmitter and focused by the antenna shoots outward

through the atmosphere in a narrow beam.

• The cloud mass, whether it is part of a typhoon or not, reflects a small fraction of the

energy bac< to the antenna.

• This reflected energy is amplified and displayed visually on a radar scope.

• The distance or slant range of the target from the radar is determined through the elapsedtime the signal is transmitted and then received as an echo.

• "irection is determined by the direction at which the focused beam is pointing at the

instant the echo is received.

• The radar is a useful tool in trac<ing and monitoring tropical cyclones.

Ground based platforms can also be classified according to operational range

• S+ort ran.e s%ste!s

+perate at ranges of )%81%%m with panoramic scanning and are often used to map building

interiors or small ob>ects

• Med#u! ran.e s%ste!s

+perate at distances of 1)%8*)%m, also achieving millimeter accuracies in high definition

surveying in '" modelling applications e.g bridge and dam monitoring

• Lon. ran.e s%ste!s

2an measure at distances of up to 1<m and are fre=uently used in open8pit mining andtopographic survey applications.

AIRBORNE PLATFORMS

BALLOON BASED MISSIONS AND MEASUREMENTS

• /igh flying balloons provide an important tool for probing the atmosphere. uch balloon

launches form an essential part of high altitude atmospheric research.

• There are three ma>or advantages of the balloon program Including the following:

1. The balloon has e9tensive altitude range they can cover. They provide a uni=ue way ofcovering a broad range of altitudes for in8situ or remote sensing measurements in the

stratosphere. +f particular interest is the **80% <m region, which is higher than the altitude

range of current aircraft such as the E8*.

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The balloon instruments provide the opportunity for additional, correlative data for

satellite based measurements, including both validation ?@atmospheric truth@ and

complementary data ?for e9ample, measurement of species not measured from the space based instrument.

'. Balloon based platforms constitute an important and ine9pensive venue for testinginstruments under development. These can be either potential instruments for unmanned

aerial vehicles ?!AC or, in some cases, for satellite based remote sensing instruments.

Rad#osonde

• adiosonde, an airborne instrument used for measuring pressure, temperature and relative

humidity in the upper air.

• The instrument is carried aloft by a meteorological balloon inflated with hydrogen.

• The radiosonde has a built8in high fre=uency transmitter that transmits data from theradiosonde meter and recorded on the ground by a specially designed radiosonde receiver.

Ra(#nsonde

• The rawinsonde is an electronic device used for measuring wind velocity, pressure,

temperature and humidity aloft. It is also attached to a balloon and as it rises through theatmosphere,

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*#nd F#nd#n. Radar

• It determines the speed and direction of winds aloft by means of radar echoes. A radar

target is attached to a balloon and it is this target that is trac<ed by ground radar. The bearing and time of interval of the echoes is evaluated by a receiver.



• In airborne remote sensing, downward or sideward loo<ing sensors are mounted on an

aircraft to obtain images of the earthDs surface.

• An advantage of airborne remote sensing, compared to satellite remote sensing, is the

capability of offering very high s2at#al resolut#on images ?*% cm or less.

• The disadvantages are low coverage area and high cost per unit area of ground coverage.

• It is not cost8effective to map a large area using an airborne remote sensing system.• Airborne remote sensing missions are often carried out as one8time operations, whereas

earth observation satellites offer the possibility of continuous monitoring of the earth.

• Analog aerial photography, videography, and digital photography are commonly used inairborne remote sensing.S%nt+et#& A2erture Radar imaging is also carried out on

airborne platforms.

• Analog photography is capable of providing high spatial resolution.

• "igital photography permits real8time transmission of the remotely sensed data to aground station for immediate analysis.

A#r&rat +a,e se,eral useul ad,anta.es as 2lator!s or re!ote sens#n. s%ste!s3

• Aircraft can fly at relatively low altitudes thus allowing for sub8meter sensor spatial

resolution.

• Aircraft can easily change their schedule to avoid weather problems such as clouds, which

may bloc< a passive sensorDs view of the ground.

• ast minute timing changes can be made to ad>ust for illumination from the sun, the

location of the area to be visited and additional revisits to that location.

• ensor maintenance, repair and configuration changes are easily made to aircraft

platforms.

• Aircraft flight paths <now no boundaries e9cept political boundaries.

D#sad,anta.es o a#r&rat as 2lator!s #n re!ote sens#n.3

• Getting permission to intrude into foreign airspace can be a lengthy and frustrating process.

• The low altitude flown by aircraft narrows the field of view to the sensor re=uiring many passes to cover a large area on the ground.

• The turnaround time it ta<es to get the data to the user is delayed due to the necessity ofreturning the aircraft to the airport before transferring the raw image data to the data

providerDs facility for preprocessing.

AIRCRAFT PLATFORMS INSTALLED IN T$E *INGS

4

http://www.crisp.nus.edu.sg/~research/tutorial/image.htm#spatial_resolution

http://www.crisp.nus.edu.sg/~research/tutorial/mw.htm#sar

http://www.crisp.nus.edu.sg/~research/tutorial/image.htm#spatial_resolution

http://www.crisp.nus.edu.sg/~research/tutorial/mw.htm#sar



SPACE BORNE PLATFORMS3

In space borne remote sensing, sensors are mounted on8board a spacecraft ?space shuttleor satellite orbiting the earth.

pace borne platforms include the following:

• oc<ets, atellites and space shuttles. pace borne platforms range from 1%% to '4%%% <m

above the earths surface.

• This is shown below,

pace shuttle: *)%8'%% <m

pace stations: '%%80%% <m ow level satellites: 5%%81)%% <m /igh level satellites: About '4%%% <m

• In space borne platforms, sensors are mounted on8board a spacecraft ?space shuttle orsatellite orbiting the earth.

S2a&e "orne re!ote sens#n. 2ro,#des t+e ollo(#n. ad,anta.es:

• arge area coverageF

• re=uent and repetitive coverage of an area of interestF

• Huantitative measurement of ground features using radiometrically calibrated sensorsF

• emi automated computerised processing and analysisF

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• elatively lower cost per unit area of coverage.

SATELLITES 3

A atellite is any ob>ect man made or natural that revolves around a planet in a circular or

elliptical path.

• In general, satellites are placed in one of three types of orbits around the Earth:

Geostationary, polar or sun8synchronous.

• The type of orbit determines the design of the sensor, its altitude with respect to the Earth,and its instantaneous field of view ?the area on the Earth which can be viewed at any

particular moment in time.

Lo( le,el satell#tes: 66-1/66 7!

• They are also referred to as the ow level Earth observation satellites ?E+.

• E+ satellites are often sun synchronous i.e. they remain fi9ed with respect to the sunwith the earth rotating under the satellite3

• These satellites are deployed as a special case of polar orbits, where each successive orbitcrosses the e=uator at intervals of 1) degrees of longitude and precessing around the entire

globe once per day.

• The satellite will pass over every location on earth at the same local solar time.

• These are the most common orbits for remote sensing satellites in order to provideillumination for passive sensors.

• Active sensors such as radar and lidar may not re=uire the unDs illumination for imaging, but they do rely on solar energy as a source of power.

• This reason and the global coverage provided by a polar orbit ma<e a sun8synchronousorbit a good choice for a space borne laser profiler.

They are divided into two broad categories namely:

i83 Polar or"#t#n. satell#tes

##83 Near 2olar or"#t#n. satell#tes

#83 Polar or"#t#n. satell#tes

• ;olar +rbiting Environmental atellites ?;+E are placed in circular sun8

synchronous orbits and their altitudes usually range from 5%% to 6%% <m, with orbital

periods of (6 to 1%* minutes.

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• ;olar orbiting satellites pass above ?or nearly above each of the EarthDs poles, and

pass over the e=uator at a different longitude, on each revolution, as illustrated in the

figure below.

• A polar orbiting satellite eventually sees every part of the EarthDs surface, which is

highly desirable for remote sensing applications, including lidar.

• ;olar orbiting satellite have a good spatial resolution, typically 18)%<m per pi9el.

• They are further subdivided into e=uatorial orbiting satellites whose orbits are within

the plane of the e=uator and polar orbiting satellites whose orbits are in the plane ofthe earths polar a9is.

##83Near 2olar or"#t#n. satell#tes

• A near polar orbit is one with the orbital plane inclined at a small angle with respect to the

earthDs rotation a9is.

• A satellite following a properly designed near polar orbit passes close to the poles and is

able to cover nearly the whole earth surface in a repeat cycle

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A near8polar sun synchronous orbit

$#.+ le,el satell#tes: A"out )0666 7!

• These are the Geostationary or geosynchronous satellites.

• They appear to be stationary with respect to the Earth, as shown in the igure below,

• They must be placed at a very high altitude ? '4,%%% <m in order to produce an orbital period e=ual to the period of EarthDs rotation.

• Any sensor onboard a geosynchronous satellite is viewing the same area of the Earth at alltimes, and because of the high latitude, this is usually a very large area.

• 2ommunications and weather satellites are the most common e9amples ofgeosynchronous orbits.

• In general, imaging and mapping satellites are not geosynchronous becauseF

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a The resolution of imagery or mapping data ac=uired from this great distance would be

very coarse,

b Most satellite remote sensing applications are based on the availability of world8widecoverage,

c ;assive remote sensing systems re=uire the unDs illumination. #hile lidar, an active

sensor, does not re=uire daylight, the first two reasons ma<e geosynchronous lidar

profilers impractical.

Ad,anta.es o Geostat#onar% Satell#tes or re!ote #!a.#n.

• The advantage of their great height is that they can view the whole earth dis<

below them, rather than a small subsection

• They can scan the same area very fre=uently ?typically every '%84% minutes. This

ma<es them ideal for meteorological applications.

D#sad,anta.es o Geostat#onar% Satell#tes or re!ote #!a.#n.

• As they are positioned at such a high altitude the spatial resolution is not as good

as some polar orbiting satellites.

• ince they are always positioned above the e=uator they canDt see the north or

south poles and are of limited use for latitudes greater than 4%85% degrees north orsouth.

• The further from the e=uator the lower the spatial resolution of each pi9el and the

greater the possibility of being hidden by the earthDs curvature. o, for a typicalMeteosat image a pi9el near the e=uator may represent a *.)$m s=uare on the

ground, but a pi9el positioned for e9ample in -orthern Europe may represent

1%$m on the ground and therefore provide less information ?such as temperature,vegetation, wind speed, albedo, etc per s=uare metre.

Meteorolo.#&al Geostat#onar% Satell#tes

1)



• 2urrently there are 4 satellites positioned at regular intervals around the e=uator so

that the whole earth is covered.

The main satellites are:

1. Meteosat

• The European community satellite operated by E!METAT ?formally part of theEuropean pace Agency in Germany is positioned above Europe&Africa ?appro9 %

degrees ongitude. This is the satellite that we receive data from "undee.

• Meteosat also rebroadcasts data from other geostationary satellites ?although at

less regular intervals than its own data.

• Meteosat transmits /I data at 14(0.) M/J, at a data rate of 144.44 <bits&s.

Meteosat satell#te

*. GOES-EAST

• +perated by the ! -+AA agency, positioned over !A&.America

?5) deg. #est

GOES-East Satell#te:

1



'. GOES-*EST 9 Geostat#onar% O2erat#onal En,#ron!ental Satell#te8

• ;ositioned over the ;acific ?1') deg. #est.

GOES-(est satell#te:

0. GMS

• +perated by the 7apanese pace Agency -A"A positioned over

7apan&Australia ?10% deg. East.

GMS Satell#te:

1/

http://www.nasda.go.jp/index_e.html

http://www.nasda.go.jp/index_e.html



/3 IODC 9Ind#an o&ean data &o,era.e8

• Meteosat8), now re8positioned at ?4' deg. East for Indian +cean "ata 2overage

IODC SATELLITE:

03 GOMS ?Geostationary +perational Meteorological atellite

• ;ositioned at ?54 deg. East

• A oviet (eat+er satell#te placed in .eostat#onar% or"#t over the Indian

+ceanF also <nown as Ele<tro.

10

http://www.daviddarling.info/encyclopedia/W/weather_satellite.html

http://www.daviddarling.info/encyclopedia/G/geostationary_orbit.html


http://www.daviddarling.info/encyclopedia/W/weather_satellite.html




• The year 1((0 witnessed the long8awaited debut of the Geostationary

+perational Meteorological atellite ?G+M system of Ele<tro spacecraft. The

ob>ectives of the program, as stated in 1((1, are as follows:

• To ac=uire, in real time, television images of the Earth surface and cloud within a radius

of 4% degrees centered at the sub8satellite point in the visible and I regions of thespectrumF

• To measure temperature profiles of the KEarth surface ?land and ocean as well as cloud

coverF

• To measure radiation state and magnetic field of the space environment at the

geostationary orbital altitudeF• To transmit via digital radio channels television images, temperature and radiation and

magnetrometric information to the Main and regional data receiving and processing

centersF

• To ac=uire the information from oviet and international data collection platforms

?"2;s, located in the G+M radio visibility, and to transmit the obtained information to

the main and regional data and processing centersF• To retransmit the processed meteorological data in the form of facsimile or

alphanumerical information from the receiving and processing centers to the independent

receiving stations via satellitesF

• To provide the e9change of high8speed digital data ?retransmissions via the satellite

between the Main and regional centers of the ! tate 2ommittee for

/ydrometeorologyF

GOMS SATELLITE

SPACE S$UTTLES AND SPACE STATIONS

1



• The two main platforms used at typical altitudes of *)%<m to 0%%<m areF

•The American pace huttle and, for now, the ussian MI orbital station.

• Both the pace huttle and the MI stations permit human interaction onboard

allowing =uic< decisions and intervention on physical related problems.

• Also, by flying at lower altitudes, these sensors obtain better resolution

information of the surface, not to mention the possibility of using non8electronic

photographic cameras.

• E9periments were carried out on the pace huttle to test the accuracies and

suitability for mapping of the M+M ?Modular +ptoelectronic Multispectral

canner, of the E2 ?Electronic till 2amera and of the 2 ?arge ormat2amera.

• The success of the tests showed that it is possible to e9tract information from

these sets of data with enough accuracy for mapping at scales 1:*),%%% and

smaller M+M has the additional advantage of ta<ing three simultaneous views

of the Earths surface from different angles, permitting a three8imagestereoscopy in the long trac< direction.

• Besides ta<ing the stereo images with smaller time delay between them, thusavoiding sun8angle variations and different illumination of the scenes, it is also

advantageous in terms of the algorithm structure The good results obtained

confirm the importance of this type of data, besides presenting the M+Msensors summariJed information, it also presented characteristics of the E2 and

of the 2.

!IA- MI +BITA TATI+-

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CONCLUSION

;latforms have gradually developed from the simple ground based

weather balloons to the more comple9 space borne satellite platforms.

Reeren&es:

1. Ebner et. al., 1(66, -eto, 1((', $ramer., 1((0.

*. Ebner et. al.,1(66

3. http:&&en.wi<ipedia.org&wi<i&un8synchronousLorbit

3 +tt2:7#dlat32a.asa3dost3.o,32+.en!et#nstru!entss2e&#al3+t!l

15

http://en.wikipedia.org/wiki/Sun-synchronous_orbit

http://kidlat.pagasa.dost.gov.ph/genmet/instruments/special.html

http://en.wikipedia.org/wiki/File:Mir_on_12_June_1998edit1.jpg

http://en.wikipedia.org/wiki/Sun-synchronous_orbit

http://kidlat.pagasa.dost.gov.ph/genmet/instruments/special.html



5. http:&&www.eol.ucar.edu&fadb&resource&show&1%*1

03+tt2s:(((3edu&at#on32su3edul#darl';23+t!l

7. https:&&www.e8education.psu.edu&lidar&l*Lp0.html

6. Introduction to remote sensing By A.; 2rac<nell and .#.B /ayes.

(. chroeder et. Al., *%%%, eige et. al., *%%%.

1%.ssec.wisc.edu

11.!niversity 2enter for Atmospheric esearch ?*%%(. acilities Assessment

"atabase

12.www.crisp.nus.edu.sg&research&...&spacebrn.htm

13.ww.satlab.hawaii.edu&...&romeiserLoceans*%%'.p

14.www.crisp.nus.edu.sg&research&...&spacebrn.htm

15.www.sat.dundee.ac.u<&pdusfa=.html

'6

http://www.eol.ucar.edu/fadb/resource/show/1021

https://www.education.psu.edu/lidar/l2_p4.html

https://www.e-education.psu.edu/lidar/l2_p4.html

http://www.eol.ucar.edu/fadb/resource/show/1021

https://www.education.psu.edu/lidar/l2_p4.html

https://www.e-education.psu.edu/lidar/l2_p4.html

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