# MicroSCOPE

> research satellite launched in 2016 which measured the universality of free fall

**Wikidata**: [Q1931562](https://www.wikidata.org/wiki/Q1931562)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/MICROSCOPE)  
**Source**: https://4ort.xyz/entity/microscope

## Summary  
MicroSCOPE is a French research satellite launched in 2016 to test the universality of free fall, a key aspect of Einstein’s equivalence principle. It was developed by CNES and operated in low Earth orbit until its decommissioning in 2018.

## Key Facts  
- Launched on April 25, 2016 at 21:02:13 UTC aboard a Soyuz-2.1a rocket from the Ensemble de Lancement Soyouz  
- Mass: 303 kilograms  
- Operated by CNES, the French space agency  
- Tested the equivalence principle with unprecedented precision using electrostatically compensated accelerometers  
- Mission active from December 2016 to October 2018  
- Orbit: Sun-synchronous  
- Built on the Myriade spacecraft bus  
- Official project website: https://cnes.fr/projets/microscope (in French)  
- COSPAR ID: 2016-025B  

## FAQs  
### Q: What was the purpose of the MicroSCOPE satellite?  
A: MicroSCOPE tested the equivalence principle—the idea that all objects fall at the same rate in a gravitational field regardless of their composition—with extreme accuracy. This principle underpins general relativity.

### Q: Who built and operated MicroSCOPE?  
A: The satellite was manufactured and operated by CNES, the French national space agency.

### Q: How long did the MicroSCOPE mission last?  
A: The satellite was launched in April 2016, entered service in December 2016, and was retired in October 2018.

## Why It Matters  
MicroSCOPE played a crucial role in fundamental physics by conducting one of the most precise tests ever performed of the equivalence principle—a cornerstone of Einstein's theory of general relativity. By comparing the accelerations of two different materials (platinum and titanium) in Earth's gravity field, it sought evidence for potential violations that could point toward new physics beyond current theories. Its findings help refine our understanding of gravity and inform future missions aimed at probing even deeper into foundational physical laws.

## Notable For  
- First dedicated satellite mission to test the equivalence principle in space with such high precision  
- Used ultra-sensitive differential accelerometers operating in drag-compensated microgravity conditions  
- Achieved results confirming the equivalence principle to within 1 part in 10^14  
- Demonstrated advanced technologies for future gravitational experiments in space  

## Body  
### Mission Overview  
MicroSCOPE (Micro-Satellite à traînée Compensée pour l'Observation du Principe d'Équivalence) was designed to perform highly accurate tests of the equivalence principle. This principle states that inertial mass and gravitational mass are equivalent, implying that all bodies should fall at the same rate in a vacuum irrespective of their composition.

The mission aimed to improve upon ground-based torsion balance experiments by eliminating seismic and atmospheric disturbances through orbital operation.

### Technical Specifications  
- **Mass**: 303 kg  
- **Power System**: Two solar arrays producing up to 140 W  
- **Spacecraft Bus**: Myriade (developed by CNES)  
- **Orbit Type**: Sun-synchronous orbit  
- **Launch Vehicle**: Soyuz-2.1a with Fregat-M upper stage (Flight No. R 15000-005)  
- **Mission Duration**: April 2016 – October 2018  

### Scientific Payload  
The core instrument was the T-SAGE (Torsion-free Satellite Gravity gradiometer for Equivalence), which included two independent differential accelerometers:
- One pair used platinum alloy test masses
- Another used titanium alloy test masses

These were monitored for any relative acceleration between the pairs, which would indicate a violation of the equivalence principle.

### Launch & Operations  
- **Launch Date**: April 25, 2016  
- **Launch Site**: Ensemble de Lancement Soyouz, Kourou, French Guiana  
- **Start of Science Operations**: December 7, 2016  
- **End of Mission**: Service retirement announced October 16, 2018; full decommissioning completed October 18, 2018  

### Results & Impact  
In 2022, final analysis confirmed no detectable difference in acceleration between the two materials, supporting the equivalence principle to a precision of approximately $1 \times 10^{-14}$. These results remain among the best constraints on alternative theories of gravity involving scalar-tensor models or extra dimensions.

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  "name": "MicroSCOPE",
  "description": "Research satellite launched in 2016 which measured the universality of free fall.",
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## References

1. [Source](https://space.skyrocket.de/doc_sdat/microscope.htm)
2. [Source](https://directory.eoportal.org/satellite-missions/microscope)
3. Jonathan's Space Report