| Aqua | |
| Names List: | EOS PM-1 |
| Insignia: | Aqua logo 72dpi.jpg |
| Insignia Size: | 125px |
| Insignia Caption: | Logotype of the mission. |
| Mission Type: | Earth observation |
| Operator: | NASA |
| Cospar Id: | 2002-022A |
| Satcat: | 27424 |
| Mission Duration: | 6 years (planned) Elapsed: |
| Spacecraft Bus: | T330 (AB-1200) |
| Manufacturer: | TRW |
| Dimensions: | 4.81x |
| Launch Mass: | 3117kg (6,872lb) |
| Power: | 4.444 kilowatts |
| Launch Date: | UTC |
| Launch Rocket: | Delta II 7920-10L D-291 |
| Launch Site: | Vandenberg SLC-2W |
| Launch Contractor: | Boeing |
| Last Contact: | 2026-2027 (planned) |
| Decay Date: | 2046 (planned) |
| Orbit Epoch: | 02 June 2016, 10:25:37 UTC |
| Orbit Reference: | Geocentric |
| Orbit Regime: | Low Earth |
| Orbit Periapsis: | 702km (436miles) |
| Orbit Apoapsis: | 703km (437miles) |
| Orbit Inclination: | 98.1987° |
| Orbit Semimajor: | 7080.6km (4,399.7miles) |
| Orbit Eccentricity: | 0.0000979 |
| Orbit Period: | 99 minutes |
| Orbit Raan: | 95.2063° |
| Orbit Arg Periapsis: | 120.4799° |
| Orbit Mean Anomaly: | 351.4268° |
| Orbit Mean Motion: | 14.57116559 |
| Orbit Rev Number: | 74897 |
| Apsis: | gee |
| Programme: | Large Strategic Science Missions Earth Science Division |
| Previous Mission: | Terra |
| Next Mission: | ICESat |
| Programme2: | Earth Observing System |
| Previous Mission2: | GRACE |
| Next Mission2: | ICESat |
Aqua (EOS PM-1) is a NASA scientific research satellite in orbit around the Earth, studying the precipitation, evaporation, and cycling of water. It is the second major component of the Earth Observing System (EOS) preceded by Terra (launched 1999) and followed by Aura (launched 2004).
The name "Aqua" comes from the Latin word for water. The satellite was launched from Vandenberg Air Force Base on May 4, 2002, aboard a Delta II rocket. Aqua operated in a Sun-synchronous orbit as the third in the satellite formation called the "A Train" with several other satellites (OCO-2, the Japanese GCOM W1, PARASOL, CALIPSO, Cloud Sat, and Aura) for most of its first 20 years; but in January 2022 Aqua left the A-Train (as Cloud Sat, CALIPSO and PARASOL had already done) when, due to its fuel limitations, it transitioned to a free-drift mode, wherein its equatorial crossing time is slowly drifting to later times, from its tightly controlled orbit.[1]
Aqua is one of NASA's missions for Earth science operating in the A-Train constellation. It has demonstrated a very high level of precision in making the primary long-term measurements of the mission. These highly calibrated climate quality measurements of radiance, reflectance, and backscatter have been used to cross-calibrate past and present sensors launched by NASA, as well as a variety of sensors launched from other agencies and the international community. Thousands of scientists and operational users from around the world have made use of the Aqua data to address NASA's 6 interdisciplinary Earth science focus areas: Atmospheric Composition, Weather, Carbon Cycle and Ecosystems, Water and Energy Cycle, Climate Variability and Change, and Earth Surface and Interior.
Aqua has experienced some minor, non-mission ending anomalies.
Because of a 2007 anomaly with the Solid State Recorder (SSR) it can only hold two orbits worth of data. A series of solar array and array regulator electronics anomalies starting in 2010 has led to the loss of 23 strings of solar cells out of a total of 132 strings.[2] A 2005 short circuit within a battery cell led to a partial loss of cell capacity. In 2009, a solar panel thermistor failed and an error in the Solar Array offset was detected. The offset issue has been corrected periodically since then. On September 8, 2007, the Dual Thruster Module (DTM-2) Heater experienced an anomaly.[3] On August 16, 2020, The Formatter Multiplexer Unit (FMU) experienced an anomaly, corrupting some data in the SSR and stopping all data streams until it was recovered on September 2, 2020.[4]
The current end of mission plan is to let Aqua's orbit decay naturally at least until June 2024 and continue data collection into 2026or even 2027, dependent on such items as budget, fuel, hardware, power, and end-of mission requirements.[2] Aqua's life could be extended with a possible re-fueling mission. A worst-case scenario would result in a re-entry by 2046.[5]
Aqua carries six instruments for studies of water on the Earth's surface and in the atmosphere, of which four are still operating:
The Aqua spacecraft has a mass of about 2850kg (6,280lb), plus propellant of about 230kg (510lb) at launch. Stowed for launch, the satellite fit in a volume of 2.68 m x 2.49 m x 6.49 m. Deployed, Aqua is 4.81 m x 16.70 m x 8.04 m.