| Lincoln Calibration Sphere 1 | |
| Names List: | LCS-1 |
| Mission Type: | radar calibration |
| Operator: | MIT Lincoln Laboratory |
| Cospar Id: | 1965-034C |
| Satcat: | 01361 |
| Mission Duration: | Elapsed: |
| Spacecraft: | LCS-1 |
| Spacecraft Type: | Aluminium sphere |
| Manufacturer: | Rohr Corp. |
| Dry Mass: | 34kg (75lb) |
| Launch Rocket: | Titan IIIA |
| Launch Site: | Cape Canaveral LC-20 |
| Launch Contractor: | US Department of Defense |
| Deployment From: | Geocentric orbit |
| Deployment Date: | 06 May 1965 |
| Disposal Type: | Re-Entry |
| Decay Date: | In c. 30,000 years |
| Apsis: | gee |
| Orbit Epoch: | May 5, 1965[1] |
| Orbit Apoapsis: | 2796km (1,737miles) |
| Orbit Periapsis: | 2786km (1,731miles) |
| Orbit Reference: | Geocentric |
| Orbit Regime: | Medium Earth |
| Orbit Raan: | 1 hour 35 minutes |
| Orbit Inclination: | 32.1° |
| Orbit Eccentricity: | 0.00055 |
| Orbit Period: | 145.6 minutes |
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] 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 passive metal sphere. LCS-1 has been used for radar calibration since its launch. It was built by Rohr. Corp. for the MIT Lincoln Laboratory.[3] [4]
LCS-1 is a hollow sphere 1.12m (03.67feet) in diameter with a wall thickness of 3.2mm.[4] 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]