Lincoln Calibration Sphere 1


Lincoln Calibration Sphere 1
Mission typeradar calibration
OperatorMIT Lincoln Laboratory
COSPAR ID1965-034C
SATCAT no.01361
Mission duration55 years, 10 months and 1 day
Spacecraft properties
Spacecraft typeAluminium sphere
ManufacturerRohr Corp.
Dry mass34 kg (75 lb)
Start of mission
Launch date15:00:03, May 6, 1965 (UTC) (1965-05-06T15:00:03Z)
RocketTitan IIIA
Launch siteCape Canaveral LC-20
ContractorUS Department of Defense
Deployed fromGeocentric orbit
Deployment date06 May 1965
End of mission
Decay dateIn c. 30000 years
Orbital parameters
Reference systemGeocentric
RegimeMedium Earth
Perigee altitude2,786 km (1,731 mi)
Apogee altitude2,796 km (1,737 mi)
Period145.6 minutes
RAAN1 hour 35 minutes
EpochMay 5, 1965[1]

The Lincoln Calibration Sphere 1, or LCS-1, is a large aluminium sphere in Earth orbit since 6 May 1965. It is still in use, having lasted for over 50 years.[2][3] The sphere was launched along with the Lincoln Experimental Satellite-2 on a Titan IIIA. It is technically the oldest operational spacecraft, but it has no power supply or fuel; it is merely a metal sphere. LCS-1 has been used for radar calibration since its launch. It was built by Rohr. Corp. for the MIT Lincoln Laboratory.[4][3]

LCS-1 is a hollow sphere 1.12 m (3 ft 8 in) in diameter with a wall thickness of 3.2 mm (0.13 in).[3] The sphere was constructed from two hemispheres, made by spinning sheet metal over a mold. These hemispheres were fastened to an internal, circumferential hoop by 440 countersunk screws, then milled and polished. The initial finish had a surface roughness less than 10 micrometres and was expected to last for five years.[5] Since its launch, I-band measurements have shown periodic deviations that likely correspond to one or more new surface irregularities.[6]

Before being launched to orbit, the optical cross section of the LCS-1 was measured in L, S, C, X and K microwave bands. Four other spheres were also manufactured and measured for comparison to the one in orbit.[7]


  1. ^ "NSSDCA - LCS". NASA. Retrieved 15 September 2017.
  2. ^ Nelson, Heather C. "Low-Earth-Orbit Target Design for Optical Calibration of the Falcon Telescope". Electronic Thesis and Dissertations for Graduate School. Pennsylvania State University. Retrieved 21 August 2019.
  3. ^ a b c "radar calibration via satellites". National Astronomy and Ionosphere Center. Acreibo Observatory. Retrieved 23 July 2015.
  4. ^ Krebs, Gunter. "LCS 1,2,3,4". Gunter's Space Page. Retrieved 23 July 2015.
  5. ^ Prosser, Reese T. (October 1965). "The Lincoln Calibration Sphere". Proceedings of the IEEE. 53 (10): 1672. doi:10.1109/PROC.1965.4319.
  6. ^ Hall, Doyle T.; Africano, John L.; Lambert, John V.; Kervin, Paul W. (July 2007). "Time-Resolved I-Band Photometry of Calibration Spheres and NaK Droplets". Journal of Spacecraft and Rockets. 44 (4): 910–919. Bibcode:2007JSpRo..44..910H. doi:10.2514/1.27464.
  7. ^ Burrows, M.L. "The Quality of the Lincoln Calibration Sphere" (PDF). Defense Technical information Center. Retrieved 22 April 2016.