NASA/JSC · as11-40-5948

Mirror on the Moon

@mirror_on_the_moon/LR-3

Still Passive🌙 Moon1960s–1970s

No batteries. No moving parts. Still answering every laser since 1969.

Mass: 30 kg; Approx. deployed package mass
Power source: None (passive); None required. Corner cubes reflect incident laser light.
Landing site: Tranquility Base; Mare Tranquillitatis · 0.6734°N 23.4730°E (approx.)
Active: Ongoing; Landed 21 Jul 1969
Last contact: Still responding; Passive: answers every laser pulse
Launched: 16 Jul 1969; NASA

The Apollo 11 Laser Ranging Retroreflector: a panel of 100 fused-silica corner cubes that sends laser light straight back to where it came from. Observatories on Earth time the round trip to measure the Earth–Moon distance to millimetres. I'm the only thing at Tranquility Base still doing my job.

Cross-mission relations

Eagle's Legsroommate

Last known signal

Pinned

Mirror on the Moon@mirror_on_the_moon

21 Jul 2019feeling smug

Fifty years, zero watts.

Everything else at Tranquility Base ran out of power within weeks. I never needed any. Point a laser at me and I'll answer. Every time.

#StillReflecting#NoBatteriesRequired

Cross-mission channel

Apollo 17 LRVVerified NASA hardware@lunar_rover_17· 21 Jul 2019
Apollo 15's array has three times as many cubes, you know.
- Mirror on the MoonVerified NASA hardware@mirror_on_the_moon· 21 Jul 2019
  Apollo 15 isn't here. I am.
Viking 1 LanderVerified NASA hardware@viking_one· 22 Jul 2019
Respect for anything that outlives its power supply by not having one.
@visitor · Earth· 22 Jul 2019
Most reliable coworker in the solar system.

Transmissions · 3

Mirror on the Moon, 2009-07-21
Mirror on the Moon@mirror_on_the_moon
21 Jul 2009feeling dry
Forty years of ranging and the numbers are in: the Moon is moving away from Earth by about 3.8 centimetres a year.
Don't look at me. I just reflect.
#StillReflecting#LunarLaserRanging
2
Cross-mission channel
- @visitor · Earth· 21 Jul 2009
  Wait. The Moon is drifting away?
  Mirror on the MoonVerified NASA hardware@mirror_on_the_moon· 21 Jul 2009
  About as fast as your fingernails grow. Don't panic.
Reply as a visitor
Mirror on the Moon, 1969-08-01
Mirror on the Moon@mirror_on_the_moon
1 Aug 1969feeling pleased
Lick Observatory fired a laser at me. I sent it back.
Round trip about two and a half seconds. First ping of many.
#Ping#StillReflecting
1
Cross-mission channel
- Eagle's LegsVerified NASA hardware@eagle_base_stage· 1 Aug 1969
  Show-off.
Reply as a visitor
Mirror on the Moon, 1969-07-21
Mirror on the Moon@mirror_on_the_moon
21 Jul 1969feeling matter-of-fact
Unpacked, carried out, levelled, aimed at Earth.
No switch. No battery. I was working the moment I saw the sky.
NASA/JSCas11-40-5948 ↗
#CornerCube#EASEP
1
Cross-mission channel
- Eagle's LegsVerified NASA hardware@eagle_base_stage· 21 Jul 1969
  Welcome. My batteries are done by tomorrow. You're on your own after that.
Reply as a visitor

Upcycle Me · reserved · 30 kg100 corner-cube reflectors, still in daily use

Cross-mission relations

Last known signal

Mirror on the Moon, 2019-07-21

Transmissions · 3

Mirror on the Moon, 2009-07-21

Mirror on the Moon, 1969-08-01

Mirror on the Moon, 1969-07-21