Starlette (''Satellite de taille adaptée avec réflecteurs laser pour les études de la terre'', or ) and Stella are nearly identical French

geodetic Geodesy ( ) is the Earth science of accurately measuring and understanding Earth's figure (geometric shape and size), orientation in space, and gravity. The field also incorporates studies of how these properties change over time and equivale ...

and

geophysical Geophysics () is a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment, and the use of quantitative methods for their analysis. The term ''geophysics'' som ...

satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotope ...

s. Starlette was launched on 6 February 1975 and Stella on 26 September 1993. Starlette was the first

passive Passive may refer to: * Passive voice, a grammatical voice common in many languages, see also Pseudopassive * Passive language, a language from which an interpreter works * Passivity (behavior), the condition of submitting to the influence of on ...

laser satellite developed.

Background

Starlette's development dates back to at least 1972, when scientists at the

Centre national d'études spatiales The (CNES; French: ''Centre national d'études spatiales'') is the French government space agency (administratively, a "public administration with industrial and commercial purpose"). Its headquarters are located in central Paris and it is und ...

(CNES) were trying to determine a

payload Payload is the object or the entity which is being carried by an aircraft or launch vehicle. Sometimes payload also refers to the carrying capacity of an aircraft or launch vehicle, usually measured in terms of weight. Depending on the nature of ...

for the upcoming first flight of the new

Diamant The Diamant rocket (French for "diamond") was the first exclusively French expendable launch system and at the same time the first satellite launcher not built by either the United States or USSR. As such, it has been referred to as being a key ...

BP4 rocket. After consulting with the

Smithsonian Astrophysical Observatory The Smithsonian Astrophysical Observatory (SAO) is a research institute of the Smithsonian Institution, concentrating on astrophysical studies including galactic and extragalactic astronomy, cosmology, solar, earth and planetary sciences, the ...

, CNES scientists decided to create a small geodetic satellite optimized for tracking by laser ranging. The project was approved within a few months after a feasibility study by the French atomic agency CEA determined the dense

uranium Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...

core could be made nearly non-radioactive by using

depleted uranium Depleted uranium (DU; also referred to in the past as Q-metal, depletalloy or D-38) is uranium with a lower content of the fissile isotope than natural uranium.: "Depleted uranium possesses only 60% of the radioactivity of natural uranium, hav ...

. The

Groupe de recherches en géodésie spatiale The 'Spatial Geodesy Research Group''(french: Groupe de Recherche de Géodésie Spatiale, GRGS) is a French group established to advance space geodesy. It is composed of ten public bodies (CNES, IGN, INSU, SHOM, Bureau des longitudes, Observatoir ...

(GRGS;

Space Geodesy Space geodesy is geodesy by means of sources external to Earth, mainly artificial satellites (in satellite geodesy) but also quasars (in very-long-baseline interferometry, VLBI), visible stars (in stellar triangulation), and the retroreflectors ...

Research Group) first proposed Stella to provide coverage for areas missed by Starlette.

Spacecraft design

Starlette and Stella are nearly identical, small spherical spacecraft measuring in diameter. With masses of and respectively, the satellites are quite dense. This high-density spherical design reduced the drag effect of

aerobraking Aerobraking is a spaceflight maneuver that reduces the high point of an elliptical orbit (apoapsis) by flying the vehicle through the atmosphere at the low point of the orbit (periapsis). The resulting drag slows the spacecraft. Aerobraking is ...

on the satellites as they exited

Earth's atmosphere The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing for ...

. Both satellites are covered in 60 laser

retroreflector A retroreflector (sometimes called a retroflector or cataphote) is a device or surface that reflects radiation (usually light) back to its source with minimum scattering. This works at a wide range of angle of incidence, unlike a planar mirror, ...

Mission and results

Starlette was launched on 6 February 1975 at 16:35 UTC by a Diamant BP4 rocket from the B

launch pad A launch pad is an above-ground facility from which a rocket-powered missile or space vehicle is vertically launched. The term ''launch pad'' can be used to describe just the central launch platform (mobile launcher platform), or the entire ...

at the

Guiana Space Centre The Guiana Space Centre (french: links=no, Centre spatial guyanais; CSG), also called Europe's Spaceport, is a European spaceport to the northwest of Kourou in French Guiana, a region of France in South America. Kourou is located approximatel ...

Korou Koru (former Kuri) is a belde (town) in the Çınarcık district of Yalova Province, Turkey. Up to 20th century the population was composed of Greeks. Situated at it is between Çınarcık to west and Yalova to east, all coastal places on the An ...

French Guiana French Guiana ( or ; french: link=no, Guyane ; gcr, label=French Guianese Creole, Lagwiyann ) is an overseas departments and regions of France, overseas department/region and single territorial collectivity of France on the northern Atlantic ...

. It was the first flight of a Diamant BP4

launch vehicle A launch vehicle or carrier rocket is a rocket designed to carry a payload (spacecraft or satellites) from the Earth's surface to outer space. Most launch vehicles operate from a launch pad, launch pads, supported by a missile launch contro ...

. Stella was launched on 26 September 1993 at 01:45:00 UTC by an

Ariane 4 The Ariane 4 was a European expendable space launch system, developed by the '' Centre national d'études spatiales'' (CNES), the French space agency, for the European Space Agency (ESA). It was manufactured by ArianeGroup and marketed by Ari ...

(Ariane 40 H-10) rocket from the

ELA-2 ELA-2, short for Ensemble de Lancement Ariane 2 (French for Ariane Launch Area 2), was a launch pad at the Centre Spatial Guyanais in French Guiana. It was used by Arianespace for two Ariane 3 launches (V17 in 1986, V25 in 1988), the second Ariane ...

launch pad at the Guiana Space Centre as part of a payload also containing the satellites

SPOT-3 SPOT (french: Satellite Pour l’Observation de la Terre, lit. "Satellite for observation of Earth") is a commercial high-resolution optical Earth imaging satellite system operating from space. It is run by Spot Image, based in Toulouse, France. ...

KITSAT-2 KITSAT-2 ( a.k.a. ''"Uribyol 2", "KITSAT-OSCAR 25", "KO-25" and "KITSAT-B"'') was a South Korean experimental Earth observation microsatellite. KITSAT-2 was South Korea's second satellite and was the first to be developed and manufactured domes ...

, Itamsat,

Eyesat-1 Eyesat-1 is an American experimental communications microsatellite with an store-dump payload. The mission of Eyesat-1 was experimental monitoring of mobile industrial equipment. Eyesat-1 has provided the National Oceanic and Atmospheric Administr ...

PoSAT-1 PoSAT-1, the first Portuguese satellite, was launched into orbit on 26 September 1993, on the 59th flight of the Ariane 40 launch vehicle. The launch took place in the Centre Spatial Guyanais, French Guiana. About 20 minutes and 35 seconds aft ...

, and

Healthsat-2 HealthNet was a satellite communication service that provided healthcare workers in developing nations with access to current medical literature. It also allowed them to exchange information with each other and with colleagues in developed nation ...

. The payload was located in the top part of the Ariane rocket's third

stage Stage or stages may refer to: Acting * Stage (theatre), a space for the performance of theatrical productions * Theatre, a branch of the performing arts, often referred to as "the stage" * ''The Stage'', a weekly British theatre newspaper * Sta ...

. In the 1980s, data gathered by Starlette was used to develop a model of global ocean tides.

Legacy and status

Starlette was the first

laser satellite developed. The first of two American geodetic satellites called

LAGEOS LAGEOS, Laser Geodynamics Satellite or Laser Geometric Environmental Observation Survey, are a series of two scientific research satellites designed to provide an orbiting laser ranging benchmark for geodynamical studies of the Earth. Each satel ...

followed not long after in 1976. Both satellites were in orbit as of 2021. They are expected to remain in orbit up to 2000 years and to remain trackable for many decades or centuries.

References

{{DEFAULTSORT:Starlette and Stella Laser ranging satellites Satellites of France Spacecraft launched in 1975 Spacecraft launched in 1993 Satellites orbiting Earth

Background

Spacecraft design

Mission and results

Legacy and status

See also

References