NASA and CNES to begin SWOT testing as its launch date approaches
From NasaSpaceFlight@1337:1/100 to All on Sat Nov 27 20:00:04 2021
NASA and CNES to begin SWOT testing as its launch date approaches
Sat, 27 Nov 2021 19:52:30 +0000
With less than one year to launch, Frances Centre National dEtudes Spatiales (CNES) and NASA The post NASA and CNES to begin SWOT testing as its launch date approaches appeared first on NASASpaceFlight.com .
FULL STORY ======================================================================
With less than one year to launch, Frances Centre National dEtudes Spatiales (CNES) and NASA are completing the final spacecraft assembly of the Surface Water and Ocean Topography (SWOT) spacecraft. SWOT is a joint NASA and CNES mission with contributions by the Canadian Space Agency (CSA) and the United Kingdom Space Agency (UKSA). The SWOT mission will be the first-ever global surveyor of all of Earths water and study how bodies of water change over time.
SWOT will launch on top of a SpaceX Falcon 9 from Space Launch Complex 4
East (SLC-4E) at Vandenberg Space Force Base (VSFB) in California. The
mission is currently scheduled for launch no earlier than November 2022.
SWOT is the latest in a series of satellites to map Earths waters in a partnership between NASA and CNES . This program started with the TOPEX/POSEIDON mission which launched in August 1992 onboard an Ariane 42P
H10 launch vehicle. The TOPEX/POSEIDON satellites used radio altimeters and precise orbit determination systems to map the Earths ocean surface
topography as well as changing sea levels. The satellite could see changes in sea levels as little as 4.2 cm.
While it was active, TOPEX/POSEIDON allowed for continuously observed global ocean topography while tracking changes in sea levels and how heat is stored in upper-level waters. Due to the failure of its pitch reaction wheel, TOPEX/POSEIDON was retired in January 2006. TOPEX/POSEIDON lasted 13 years, well beyond its planned three-year mission. The seven satellite altimeters (Credit: NASA JPL)
The success of TOPEX/POSEIDON led NASA and the CNES to continue the partnership with the follow-on Jason satellite program. The Jason program started as a dedicated program to continue the mission started by TOPEX/POSEIDON, with the same goals as its predecessor but with better accuracy and operation with more than one satellite at a time.
The first satellite, Jason-1, was launched in 2001 . Since then two more missions under the Jason name were launched in 2008 and 2016. A fifth satellite, Sentinel 6 Michael Freilich, launched in 2020. It uses the same technology but under the Sentinel name in a partnership with the European Space Agency. The mission is also known as Jason Continuity of Service (Jason-CS). A second mission, Sentinel 6B/Jason-CS B, will launch in 2025. With still operating Jason 3 and Sentinel 6, the Jason program continues the legacy created by the TOPEX/POSEIDON.
SWOT began in 2007 as a recommendation from the National Research Council Decadal Survey. The mission is a spinoff from the Jason program using many of the same technologies. From 2007 to 2015, the mission underwent conceptual studies and technology developments. In 2015, it began preliminary design and technology completion. In 2016, it was approved for implementation and began final design and fabrication.
The SWOT spacecraft consists of two main parts: the payload suite and the satellite bus.
In 2015, Thales Alenia Space (TAS) was selected to make the satellite bus.
The bus used for SWOT is TASs newest satellite bus to meet Frances Space Operations Act. This act aims to limit space debris and lower the risk of atmospheric reentry over inhabited areas. The new bus will allow any
satellite using the bus to control itself during reentry to ensure a safe disposal.
The satellite bus will be used to house many components to support the
payload suite. The bus is placed below the suite when construction is complete. It will use an S-band antenna to allow radio communications between the spacecraft and ground stations. A command and data handler will be used
to manage the spacecrafts communication and various other tasks. Twin solar arrays will be used to provide electrical power. Artist impression of the
SWOT satellite bus. (Credit: NASA)
The bus will also house the spacecrafts propulsion and attitude control
system (ACS). The ACS will use star trackers with magnetic torque rods and reaction wheels to control where the spacecraft is pointing. The spacecraft has eight 22-Newton hydrazine thrusters to control the spacecrafts orbit.
On top of the satellite bus is the payload suite. The suite will house six instruments, including an X-band antenna, to conduct SWOTs mission. Unlike
the bus, which was made in France, the suite was constructed at NASAs Jet Propulsion Laboratory in California. The instruments are provided by all four contributing space agencies.
The primary instrument, the Ka-band Radar Interferometer (KaRIn), is provided and developed by JPL. CSA and UKSA will provide components for KaRIn.
KaRIn will use interferometry to measure ocean and surface water levels. The instrument will use two antennas to see the water levels with a 60 km wide swath for each antenna. A 20-meter gap will take place between the two
While in operation it will have a low and high-resolution mode. The low resolution will be used over oceans with more onboard processing. High resolution will be used in broad, primarily continental, regions to focus on hydrology studies. The two antennas will be enclosed during launch. Following the launch, the antennas will deploy allowing global water level observation. See Also SWOT Updates SpaceX Missions Section L2 SpaceX Section Click here to Join L2
To fill in most of the 20-meter gap, CNES will provide two instruments. A Jason-class Nadir altimeter will be used to collect the data between the
KaRIn swaths gap. The Nadir altimeter will send signals to the sea surface
and will use the signals round trip time to determine the height.
The second instrument, the Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) antenna, will be provided to support the
Nadir altimeter. The DORIS antenna will pick up ground-based radio signals to determine SWOTs orbit. A Global Positioning System (GPS) receiver provided by JPL will be used in tandem with the Nadir altimeter and DORIS antenna to gain precise orbit determination.
JPL will also provide two other instruments for SWOT. The JPL-provided Laser Reflector Assembly will use mirrors and ground-based lasers for in-orbit tracking as well as additional orbit determination. The final instrument is a Microwave Radiometer to measure water vapor. The radiometer will send signals to the earth and if the signals are slow, there is more water vapor present.
After the payload suite was completed, it was delivered via a US Air Force C-17 to TAS in France on June 30, 2021. In August 2021, with the help of CNES and JPL teams, the suite was mated on top of the satellites bus by TAS. La charge utile (linstrument) du satellite #SWOT (dont lobjectif est dtudier les ocans et les fleuves) a t livre par @NASAJPL sur le site de Cannes de @Thales_Alenia_S . #SWOT est une mission conjointe du CNES et de la @NASA .
The best part has been seeing two complex systems that were built across the world from each other by different teams come together and work, said JPLs Said Kaki, the deputy project manager for SWOT.
Primary spacecraft assembly allowed TAS to complete the final assembly of the spacecraft. This can include any additions including the electrical systems and hardware to the spacecraft. The final assembly of the SWOT spacecraft can allow the TAS teams to start final launch testing.
In the coming months prior to the launch of SWOT, testing will begin to see
if the spacecraft can survive the harsh environment of a launch and space.
The testing for SWOT will take place in three phases.
The first phase is to test the spacecraft if it can survive the environment
of a launch. The teams will attach the satellites to a shake table and later an acoustic chamber. This can allow the spacecraft to be shaken and blasted with sounds to simulate a launch.
From there the spacecraft will be placed in a thermal vacuum chamber to mimic the vacuum and extreme temperature changes it will experience in space. The final phase of testing will include checks for electromagnetic interference.
Once the satellite passes testing, final hardware will be installed on the spacecraft before delivery to VSFB for launch.
After that, we button up the spacecraft and ship it to the launch site, said Kaki. At Vandenberg, the team will put the finishing touches on the satellite to ready it for launch, which is scheduled for no earlier than November 2022.
The science team for SWOT is also preparing for when the spacecraft is in orbit. The team is conducting simulations to ensure they are ready for when SWOT is in orbit collecting science. The science team is in support of
several space agencies all over the globe.
The best part of my job as the missions project scientist is being able to work with a large international research team with diverse interests and backgrounds in oceanography and hydrology, said Lee-Lueng Fu, the JPL project scientist for SWOT. This experience has broadened the horizon of my
scientific career even after 40 years of devotion to Earth research.
To help support the SWOT mission, NASA developed the AirSWOT mission. AirSWOT is an airborne instrument based on the B2000 Super King Air aircraft operated by the NASA Armstrong Flight Research Center. AirSWOT uses the Ka-Band SWOT Phenomenology Airborne Radar (KaSPAR) to collect two swaths of data on the ground.
The AirSWOT is used to collect data to understand the natural properties of Earth, while also being used to better understand the data soon to be collected by SWOT. AirSWOT is currently in use and will also be used post-launch. It can be used to prepare the team for the data from SWOT and help calibrate the data collected by the satellite. Falcon 9 (B1063-3) vertical at SLC-4E before the launch of NASAs Double Asteroid Redirection
Test (DART) mission. (Credit: Jack Beyer for NSF)
A SpaceX Falcon 9 will place the roughly 2,000 kg satellite in near-polar orbit. Falcon 9 was selected as SWOTs launch vehicle by NASAs Launch Service Program (LSP) in November 2016 .
The satellites will be placed in an initial 857 km circular orbit at 77.6 degrees inclination. The satellite remains in this orbit for the first six months after launch to conduct fast-sampling. In the first 85 days after launch, the satellite will start on-orbit checkouts and begin its commissioning period. The following 90 days will begin SWOTs calibration.
Once complete, the satellite will spend a week raising its orbit to the operational altitude. Once at its 891 km operational orbit, SWOT will begin its three-year mission. In this orbit, SWOT will be able to see 86% of the planet. The spacecraft will observe the ground with overlapping measurements that have an average revisit time of 11 days.
NASA and CNES will jointly operate the satellite in orbit. S-Band communications will be used to control and talk to the spacecraft and X-Band communications will be used for payload data.
The satellite will talk with ground stations 21 times per day. After both
NASA and CNES receive the information from the satellite, the data will be processed and released within 60 days.
Lead photo: Thales Alenia Space integrates the payload and satellite bus together. (Credit: Thales Alenia Space)
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