# GRAIL-A

> former NASA lunar orbiter

**Wikidata**: [Q28472954](https://www.wikidata.org/wiki/Q28472954)  
**Source**: https://4ort.xyz/entity/grail-a

## Summary
GRAIL-A, also known by the nickname "Ebb," was a former NASA lunar orbiter and part of the Gravity Recovery and Interior Laboratory (GRAIL) mission. Manufactured by Lockheed Martin Space and launched on September 10, 2011, the spacecraft was designed to orbit the Moon to study its gravitational field. The mission concluded on December 17, 2012, when GRAIL-A was intentionally impacted into the lunar surface.

## Key Facts
- **Also Known As:** Gravity Recovery and Interior Laboratory A; Ebb.
- **Launch Date:** September 10, 2011, at 13:08:52 UTC.
- **Launch Site:** Cape Canaveral Space Launch Complex 17B.
- **Launch Vehicle:** Delta II (specifically the D356 variant).
- **Mission End:** December 17, 2012, at 22:28:51 UTC, via lunar impact.
- **Mass:** 307 kilograms (launch weight); 201 kilograms (dry weight).
- **Dimensions:** 1.09 meters (length) × 0.95 meters (width) × 0.76 meters (height).
- **Manufacturer:** Lockheed Martin Space.
- **Operator:** Jet Propulsion Laboratory (project management); Lockheed Martin Space (spacecraft operation).
- **Identifiers:** COSPAR ID 2011-046A; NSSDCA ID 2011-046A; NAIF ID -177.

## FAQs
### Q: What was the GRAIL-A spacecraft?
A: GRAIL-A was a NASA lunar orbiter, also named "Ebb," launched in 2011 as part of a dual-spacecraft mission to create a high-resolution map of the Moon's gravitational field.

### Q: When and how did GRAIL-A launch?
A: GRAIL-A launched on September 10, 2011, aboard a Delta II rocket (variant D356) from Cape Canaveral Space Launch Complex 17B in the United States.

### Q: How did the GRAIL-A mission end?
A: The mission concluded on December 17, 2012, when the spacecraft was deliberately crashed into the Moon in a controlled lunar impact near the feature designated LQ01.

## Why It Matters
GRAIL-A represents a key component of NASA's robotic exploration of the Moon. As the first element of the twin-spacecraft Gravity Recovery and Interior Laboratory (GRAIL) mission, it played a vital role in measuring the Moon's gravity field in unprecedented detail. By flying in tandem with its sibling craft, GRAIL-A helped scientists peer into the Moon's internal structure and composition, advancing the understanding of thermal evolution and the history of rocky planets.

The mission demonstrated precise engineering and interplanetary operations managed by the Jet Propulsion Laboratory and executed by Lockheed Martin Space. Its planned destruction via lunar impact in December 2012 was a calculated end-of-mission maneuver, ensuring the spacecraft did not interfere with future lunar heritage sites while providing final scientific data.

## Notable For
- **Twin Spacecraft Configuration:** Operating as "Ebb" alongside "Flow" (GRAIL-B) to perform gravity mapping.
- **Unique Identifier:** Assigned the NAIF ID -177 for navigation and data archiving purposes.
- **Delta II Launch:** Being one of the many scientific payloads launched on the reliable, now-retired, Delta II expendable launch system.
- **Controlled Impact:** Concluding its operational life through a precise impact on the lunar surface on December 17, 2012.

## Body

### Design and Specifications
GRAIL-A was a compact spacecraft manufactured by Lockheed Martin Space. It had a launch mass of 307 kilograms and a dry mass of 201 kilograms. The bus structure measured approximately 1.09 meters in length, 0.95 meters in width, and 0.76 meters in height.

The spacecraft was powered by a photovoltaic system and utilized a nickel–hydrogen battery system comprising 10 cells to manage energy storage.

### Mission Timeline
**Launch and Early Operations**
GRAIL-A launched from Cape Canaveral Space Launch Complex 17B on September 10, 2011, at 13:08:52 UTC. It was lifted into space aboard a Delta II launch vehicle (variant D356). The United States was the country of origin for the mission.

**Lunar Operations**
The spacecraft successfully completed orbit insertion around the Moon on December 31, 2011.

**End of Mission**
Following its operational phase, GRAIL-A was decommissioned via a lunar impact on December 17, 2012, at 22:28:51 UTC. The impact occurred at the lunar feature designated LQ01.

### Management and Operations
The GRAIL project was managed by the Jet Propulsion Laboratory. Day-to-day spacecraft operations were conducted by Lockheed Martin Space. The mission is officially classified as a "former entity," having ceased operations in 2012.

## References

1. [Source](https://news.lockheedmartin.com/2007-12-19-Lockheed-Martin-Spacecraft-to-be-Flown-for-NASAs-GRAIL-Lunar-Mission)
2. [Source](http://moon.mit.edu/operations.html)
3. Jonathan's Space Report
4. [Source](https://www.nasa.gov/pdf/582116main_GRAIL_launch_press_kit.pdf)
5. [Source](https://www.nasa.gov/mission_pages/grail/news/grailstatus20121217.html)
6. [Source](https://www.economist.com/science-and-technology/2012/12/22/grail-hunt)
7. [Source](https://www.universetoday.com/92252/first-grail-twin-enters-lunar-orbit-nasas-new-years-gift-to-science/)
8. [Source](https://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/req/naif_ids.html)