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

geodetic Geodesy or geodetics is the science of measuring and representing the geometry, gravity, and spatial orientation of the Earth in temporally varying 3D. It is called planetary geodesy when studying other astronomical bodies, such as planets ...

and

geophysical Geophysics () is a subject of natural science concerned with the physical processes and properties of Earth and its surrounding space environment, and the use of quantitative methods for their analysis. Geophysicists conduct investigations acros ...

satellite A satellite or an artificial satellite is an object, typically a spacecraft, placed into orbit around a celestial body. They have a variety of uses, including communication relay, weather forecasting, navigation ( GPS), broadcasting, scient ...

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 ...

laser satellite developed.

Background

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

Centre national d'études spatiales CNES () is the French national space agency. Headquartered in central Paris, the agency is overseen by the ministries of the Ministry of Armed Forces (France), Armed Forces, Ministry of Economics and Finance (France), Economy and Finance and Min ...

(CNES) were trying to determine a payload 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 Astrophysics, astrophysical studies including Galactic astronomy, galactic and extragalactic astronomy, cosmology, Sun, solar ...

, CNES scientists decided to create a small geodetic satellite optimized for tracking by

laser ranging A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word ''laser'' originated as an acronym for light amplification by stimulated emission of radi ...

. 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; it has chemical symbol, 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. Ura ...

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 Uranium-235, 235U than natural uranium. The less radioactive and non-fissile Uranium-238, 238U is the m ...

. The Groupe de recherches en géodésie spatiale (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 retroreflect ...

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 on the satellites as they exited

Earth's atmosphere The atmosphere of Earth is composed of a layer of gas mixture that surrounds the Earth's planetary surface (both lands and oceans), known collectively as air, with variable quantities of suspended aerosols and particulates (which create weathe ...

. Both satellites are covered in 60 laser

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

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 c ...

at the

Guiana Space Centre The Guiana Space Centre (; CSG), also called Europe's Spaceport, is a spaceport to the northwest of Kourou in French Guiana, an Overseas departments and regions of France, overseas region of France in South America. Kourou is located approxim ...

in Korou,

French Guiana French Guiana, or Guyane in French, is an Overseas departments and regions of France, overseas department and region of France located on the northern coast of South America in the Guianas and the West Indies. Bordered by Suriname to the west ...

. It was the first flight of a Diamant BP4

launch vehicle A launch vehicle is typically a rocket-powered vehicle designed to carry a payload (a crewed spacecraft or satellites) from Earth's surface or lower atmosphere to outer space. The most common form is the ballistic missile-shaped multistage ...

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

Ariane 4 The Ariane 4 was a European expendable rocket, expendable launch vehicle in the Ariane (rocket family), Ariane family, developed by the (CNES), the Government of France, French space agency, for the European Space Agency (ESA). The manufacturi ...

(Ariane 40 H-10) rocket from the

ELA-2 The Guiana Space Centre (; CSG), also called Europe's Spaceport, is a spaceport to the northwest of Kourou in French Guiana, an overseas region of France in South America. Kourou is located approximately north of the equator at a latitude o ...

launch pad at the Guiana Space Centre as part of a payload also containing the satellites SPOT-3,

KITSAT-2 KITSAT-2 (Pseudonym, a.k.a. ''"Uribyol 2", "KITSAT-OSCAR 25", "KO-25" and "KITSAT-B"'') was a South Korean experimental Earth observation satellite, Earth observation Small satellite, microsatellite. KITSAT-2 was South Korea's second satellite ...

, Itamsat,

Eyesat-1 Eyesat-A was launched on September 26, 1993 using an Ariane 4 rocket at Guiana Space Centre, Kourou, French Guiana, along with SPOT-3, Stella (satellite), Stella, Healthsat-2, KITSAT-2, and PoSAT-1. References

{{Orbital launches in 1993 Sat ...

PoSAT-1 PoSAT-1 (OSAT-OSCAR 28, OSCAR 28, PO 28, 1993-061G), the first Portugal, Portuguese satellite, was launched into orbit on 26 September 1993, on the 59th flight of the Ariane 4, Ariane 4 launch vehicle. The launch took place in the Guiana Space C ...

, and Healthsat-2. The payload was located in the top part of the Ariane rocket's third

stage Stage, stages, or staging may refer to: Arts and media 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 Brit ...

. 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 ...

followed not long after in 1976. Both satellites were in orbit as of 2023. 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