Starlette and Stella

{{Short description|French geodetic and geophysical satellites}} {{other uses|Starlet (disambiguation){{!}}Starlet|Stella (disambiguation){{!}}Stella}} {{Infobox spaceflight | name = Starlette | names_list = Satellite de taille adaptée avec réflecteurs laser pour les études de la terre | image = Starlette Satellite.jpg | image_caption = | mission_type = Scientific | operator = CNES | Harvard_designation = 1975-010A | SATCAT = 7646 | mission_duration = Elapsed: {{time interval|6 February 1975, 16:35|show=ymd}} | spacecraft_bus = | manufacturer = CNES | dry_mass = | launch_mass = {{convert|47|kg|abbr=on}} | power =  | launch_date = {{start-date|6 February 1975, 16:35|timezone=yes}} UTC | launch_rocket = Diamant BP4 | launch_site = Guiana Space Centre | last_contact = | decay_date = | orbit_epoch = | orbit_reference = Geocentric | orbit_regime = Low Earth | orbit_periapsis = {{convert|812|km|abbr=on}} | orbit_apoapsis = {{convert|1114|km|abbr=on}} | orbit_inclination = 49.83 degrees | orbit_semimajor = | orbit_eccentricity = 0.0206<ref name="kramer">{{cite book |last1=Kramer |first1=Herbert J. |title=Observation of the Earth and its Environment: Survey of Missions and Sensors |date=2002 |publisher=Springer Verlag |location=Berlin |edition=4th |isbn=3-540-42388-5 |url=https://directory.eoportal.org/web/eoportal/satellite-missions/s/starlette |access-date=18 March 2021}}</ref> | orbit_period = 104 minutes | apsis = gee }} {{Infobox spaceflight | name = Stella | names_list = | image = Starlette Satellite.jpg | image_caption = | mission_type = Scientific | operator = CNES | Harvard_designation = 1993-061B | COSPAR_ID = 1993-061B | SATCAT = 22824 | mission_duration = Elapsed: {{time interval|26 September 1993, 01:45:00|show=ymd}} | spacecraft_bus = | manufacturer = CNES | dry_mass = | launch_mass = {{convert|48|kg|abbr=on}} | power =  | launch_date = {{start-date|26 September 1993, 01:45:00|timezone=yes}} UTC | launch_rocket = Ariane 4 | launch_site = Guiana Space Centre | last_contact = | decay_date = | orbit_epoch = | orbit_reference = Geocentric | orbit_regime = Low Earth | orbit_periapsis = {{convert|804|km|abbr=on}} | orbit_apoapsis = {{convert|812|km|abbr=on}} | orbit_inclination = 98.68 degrees | orbit_semimajor = | orbit_eccentricity = 0.0006<ref name="n2y0">{{cite web |author= |url=https://www.n2yo.com/satellite/?s=22824 |website= n2yo.com |title= Stella TLE |accessdate=2024-06-07 }}</ref> | orbit_period = 101 minutes | apsis = gee }}

'''Starlette''' (''Satellite de taille adaptée avec réflecteurs laser pour les études de la terre'',<ref name="kramer"/><ref name="gunther">{{cite web |last1=Krebs |first1=Gunther |title=Starlette / Stella |url=https://space.skyrocket.de/doc_sdat/starlette.htm |website=Gunther's Space Page |access-date=18 March 2021}}</ref> or {{literal translation|Satellite of suitable size with laser reflectors for studies of the earth}}) and '''Stella''' are nearly identical French geodetic and geophysical satellites. Starlette was launched on 6 February 1975 and Stella on 26 September 1993. Starlette was the first passive laser satellite developed.

==Background== Starlette's development dates back to at least 1972, when scientists at the Centre national d'études spatiales (CNES) were trying to determine a payload for the upcoming first flight of the new Diamant BP4 rocket.<ref name="barlier-lefebvre">{{cite book |last1=Barlier |first1=François |last2=Lefebvre |first2=Michel |editor1-last=Bleeker |editor1-first=Johan A. M. |editor2-last=Geiss |editor2-first=Johannes |editor3-last=Huber |editor3-first=Martin C. E. |title=The Century of Space Science |date=2001 |publisher=Kluwer Academic Publishers |location=Netherlands |isbn=978-94-010-0320-9 |pages=1623–1651 |url=http://www.ipgp.jussieu.fr/~tarantola/Files/Professional/Teaching/Seminar/Texts/Barlier-Lefebvre.pdf |access-date=18 March 2021 |chapter=A new look at planet Earth: Satellite geodesy and geosciences}}</ref> After consulting with the Smithsonian Astrophysical Observatory, CNES scientists decided to create a small geodetic satellite optimized for tracking by laser ranging.<ref name="barlier-lefebvre"/> The project was approved within a few months after a feasibility study by the French atomic agency CEA determined the dense uranium core could be made nearly non-radioactive by using depleted uranium.<ref name="barlier-lefebvre"/><ref>{{cite web |last1=ILRS |title=Starlette and Stella |url=https://ilrs.gsfc.nasa.gov/missions/satellite_missions/current_missions/stel_general.html |website=Current Missions |publisher=International Association of Geodesy |access-date=3 July 2021}}</ref>

The Groupe de recherches en géodésie spatiale (GRGS; Space Geodesy Research Group) first proposed Stella to provide coverage for areas missed by Starlette.<ref name="sshp">{{cite web |title=STELLA - The centimetre over centuries |url=http://centaur.sstl.co.uk/SSHP/data/data_stella.html |website=Small Satellites Home Page (SSHP) |archive-url=https://web.archive.org/web/20130428021115/http://centaur.sstl.co.uk/SSHP/data/data_stella.html |archive-date=28 April 2013 |date=1995}}</ref>

==Spacecraft design== Starlette and Stella are nearly identical, small spherical spacecraft measuring {{convert|24|cm|in}} in diameter.<ref name="gunther"/> With masses of {{convert|47|kg|lb}} and {{convert|48|kg|lb}} respectively, the satellites are quite dense.<ref name="gunther"/> This high-density spherical design reduced the drag effect of aerobraking on the satellites as they exited Earth's atmosphere. Both satellites are covered in 60 laser retroreflectors.<ref name="kramer"/><ref name="gunther"/>

==Mission and results== Starlette was launched on 6 February 1975 at 16:35 UTC<ref name="log">{{cite web |last1=McDowell |first1=Jonathan |title=Launch Log |url=https://planet4589.org/space/log/launchlog.txt |website=Jonathan's Space Report |access-date=18 March 2021}}</ref> by a Diamant BP4 rocket from the B launch pad at the Guiana Space Centre in Korou, French Guiana.<ref name="kramer"/><ref name="gunther"/><ref name="wade-starlette">{{cite web |last1=Wade |first1=Mark |title=Starlette |url=http://www.astronautix.com/s/starlette.html |archive-url=https://web.archive.org/web/20161221162353/http://www.astronautix.com/s/starlette.html |url-status=dead |archive-date=December 21, 2016 |website=Astronautix |access-date=18 March 2021}}</ref> It was the first flight of a Diamant BP4 launch vehicle.<ref name="kramer"/><ref name="barlier-lefebvre"/>

Stella was launched on 26 September 1993 at 01:45:00 UTC<ref name="log"/> by an Ariane 4 (Ariane 40 H-10) rocket from the ELA-2 launch pad at the Guiana Space Centre as part of a payload also containing the satellites SPOT-3, KITSAT-2, Itamsat, Eyesat-1, PoSAT-1, and Healthsat-2.<ref name="kramer"/><ref name="gunther"/><ref name="wade-stella">{{cite web |last1=Wade |first1=Mark |title=STELLA |url=http://www.astronautix.com/s/stella.html |archive-url=https://web.archive.org/web/20161228033408/http://astronautix.com/s/stella.html |url-status=dead |archive-date=December 28, 2016 |website=Astronautix |access-date=18 March 2021}}</ref> The payload was located in the top part of the Ariane rocket's third stage.<ref name="kramer"/>

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

==Legacy and status== Starlette was the first passive laser satellite developed.<ref name="barlier-lefebvre"/> The first of two American geodetic satellites called LAGEOS followed not long after in 1976.<ref name="barlier-lefebvre"/>

Both satellites were in orbit as of 2023.<ref name="kramer"/> They are expected to remain in orbit up to 2000 years and to remain trackable for many decades or centuries.<ref name="barlier-lefebvre"/><ref name="sshp"/>

==See also== {{Portal|Spaceflight}} * Satellite laser ranging * French space program * Timeline of artificial satellites and space probes

==References== {{Reflist}}

{{DEFAULTSORT:Starlette and Stella}} Category:Laser ranging satellites Category:Satellites of France Category:Spacecraft launched in 1975 Category:Spacecraft launched in 1993 Category:Satellites orbiting Earth Category:Spacecraft launched by Ariane 4 rockets