The Creepy, Kitschy and Geeky Patches of US Spy Satellite Launches / 2º parte

Check our fisrt post about the same stuff in the next link:

https://clevercatandwiseowl.wordpress.com/2015/02/10/the-creepy-kitschy-and-geeky-patches-of-us-spy-satellite-launches/

NROL-45

ULA Delta IV launches with NROL-45

Wednesday’s mission, which was the first for the Delta IV since its successful deployment of a Wideband Global Satcom spacecraft last July, marked the thirty-first flight of the Delta IV and the rocket’s sixth mission from Vandenberg.

Flying in the Medium+(5,2) configuration, the rocket is carrying out the classified NRO Launch 45 (NROL-45) mission for the National Reconnaissance Office (NRO).

Although the NRO keeps most details of its satellites and their missions classified, analysis of the information that is publicly available and comparison with previous missions often allows inferences to be made as to the nature of the spacecraft being launched.

Because it is launching from Vandenberg, Wednesday’s mission can immediately be assumed to be targeting a highly-inclined orbit; lower-inclination trajectories such as geosynchronous orbits cannot be reached from the Western Range as they would require the rocket to overfly the Continental United States.

 

Recent NRO launches from Vandenberg have targeted sun-synchronous orbits for optical imaging, highly elliptical orbits for signals intelligence (SIGINT) satellites and low Earth orbits for ocean surveillance and radar imaging spacecraft.

Navigation warnings in effect at the time of the launch suggest that the rocket will fly to the southwest, along an azimuth of approximately 222 degrees which would result in an orbit with an inclination of around 123 degrees. Termed a retrograde orbit, a course at this inclination results in the satellite orbiting in the opposite direction to the rotation of the Earth.

Other than sun-synchronous orbits, which are often slightly retrograde due to the orbital dynamics involved in maintaining such an orbit, it is unusual for a spacecraft to be placed into a retrograde orbit. The NRO has previously used such trajectories for three missions; NROL-41 or USA-215, NROL-25 or USA-234 and NROL-39 (USA-247).

The NROL-25, 39 and 41 satellites are all believed to be radar imaging satellites, part of a program which documents leaked by Edward Snowden to the Washington Post revealed to be named Topaz.

Likely the radar imaging element of the otherwise cancelled Future Imagery Architecture program, these are part of a series of five Block I satellites. An enhanced Block II was funded from 2013 which launches expected in the future.

An early EELV contract pre-solicitation, dated June 2002 with reference number 63, lists all three of these among four missions that the US Air Force was proposing to award to the Delta IV, which was then under development by Boeing. The fourth and final mission in the document – at the time scheduled for the 2007 US financial year – is the one which will launch Wednesday.

The NROL-39 and 41 missions ended up launching on the Atlas V; in 2002 there were no plans to upgrade Vandenberg’s Atlas launch facilities for the Atlas V, so all West Coast missions were automatically awarded to the Delta.

NROL-25 was the payload for an April 2012 Delta IV launch out of Vandenberg, which used the same Medium+(5,2) configuration that is being used for NROL-45. This is the only previous launch to use that configuration, which is the least-flown version of the Delta IV.

As a result of this, the NROL-45 payload is almost certainly the fourth Topaz satellite, bound for a retrograde low Earth orbit to begin a radar reconnaissance mission.

If the documents published by the Washington Post are correct, and there are five first-generation satellites, this leaves next year’s NROL-47 mission – which will also fly atop a Delta IV Medium+(5,2) – the most likely candidate to complete the series.

An alternative but less likely interpretation of the same document is that the series consists of a prototype – likely the failed NROL-21 or USA-193 satellite – followed by four first-generation spacecraft with NROL-47 the beginning of the second generation.

The Topaz series is a replacement for the earlier satellites, named Lacrosse or Onyx, which were launched between 1988 and 2005. Larger than Topaz, the first Lacrosse was deployed from Space Shuttle Atlantis during 1988’s STS-27 mission while the remaining satellites launched on Titan IV rockets.

Lacrosse used two orbital planes, inclined at 57 and 68 degrees respectively. The 123-degree retrograde orbit of the Topaz series covers the same latitudes as the 57-degree Lacrosse orbit.

The Delta IV launched on Wednesday sported the flight, or Delta, number 373. Flying in the Medium+(5,2) configuration it consists of a single Common Booster Core (CBC) first stage powered by an RS-68A engine. The stage burns liquid hydrogen propellant, oxidised by liquid oxygen.

Attached at the base are a pair of GEM-60 solid rocket motors which provide additional thrust during the early stages of ascent.

The second stage, a five-metre Delta Cryogenic Second Stage (DCSS), is powered by an RL10B-2 engine which burns the same combination of cryogenic propellants as the first stage. The DCSS is restartable and is expected to make two burns prior to spacecraft separation and subsequently deorbit itself.

 

 

The Delta IV’s launch pad at California’s Vandenberg Air Force Base is Space Launch Complex 6 (SLC-6). Originally constructed during the 1960s to support Titan IIIM launches as part of the Manned Orbiting Laboratory (MOL) program, the facility never saw a launch and was subsequently rebuilt as a West-Coast launch complex for NASA’s Space Shuttle.

At a time when the Shuttle was seen as the future of all US orbital launches, the pad at Vandenberg would have been predominantly used for military launches, including the deployment of reconnaissance satellites. After the loss of Challenger in 1986 plans to launch the Shuttle from Vandenberg were shelved as part of a program safety review, and the complex remained unused.

SLC-6 was finally used for a launch in August 1995, when Lockheed’s small Athena I rocket made its maiden flight from the pad, with an unsuccessful attempt to orbit the GemStar satellite.

Three more Athenas flew from Vandenberg between 1997 and 1999; scoring a total of two successes and two failures. Following Athena’s retirement in 2001 Space Launch Complex 6 was repurposed for the Delta IV. Should it be called upon to launch from Vandenberg again, the since-revived Athena will instead fly from nearby Space Launch Complex 8.

The first Delta launch from Space Launch Complex 6 occurred in June 2006, with NROL-22.

The pad is able to support both the Medium and Heavy forms of the rocket, with the latter being used to orbit optical reconnaissance satellites descended from the KH-11 “Crystal”.

Many details of the flight plan for Wednesday’s launch were kept secret due to the nature of the mission.

The Delta IV launch saw its first stage ignite its RS-68A engine five and a half seconds before the countdown reached zero, with booster ignition and liftoff occurring at the zero mark in the count.

Climbing out over the Pacific, Delta 373 reached Mach 1, the speed of sound, approximately 50 seconds after liftoff. About twelve seconds later it passed through the area of maximum dynamic pressure, or Max-Q.

The twin GEM-60 motors augmented the first stage for the first hundred seconds of the flight, before depleting their solid propellant and burning out. About ten seconds later the spent motors jettisoned from the vehicle.

About three and a half minutes after launch, with Delta 373 of the atmosphere, the payload fairing separated from around the NROL-45 payload at the nose of the rocket. Once the fairing has separated no further information about the mission will be released by the NRO or United Launch Alliance – other than confirmation as to whether the launch was successful or not.

It is expected the Common Booster Core continued to burn until about four minutes and six seconds after launch; with stage separation occurring six seconds later. Following separation, the second stage RL10 engine will have deployed its extendable nozzle ahead of ignition, which would have taken place thirteen seconds after staging.

Timings for the second stage burns are not known, however the first is likely to be longer; around twelve and a half minutes in duration. After this the flight will enter a coast phase before the upper stage restarts for a shorter burn – likely to last around 14 seconds – about an hour later.

Once this burn is complete, NROL-45 will separate from the rocket.

The target orbit for Wednesday’s mission will be close to the Topaz satellites’ operational orbits, which are roughly circular at altitudes a little below 1,100 kilometres (680 miles, 590 nautical miles). After separation the DCSS will perform a third burn to deorbit itself, with reentry expected over the Indian Ocean during its second revolution.

Wednesday’s launch was the second of the year for the Delta IV’s operator, United Launch Alliance (ULA). Formed in December 2006, ULA took over operations of the Delta II and IV rockets from Boeing and the Atlas V from Lockheed Martin, bringing the US Air Force’s fleet of Evolved Expendable Launch Vehicles (EELVs) under one roof.

ULA provides launch services for US Government missions, and is contracted through Boeing and Lockheed Martin for commercial and foreign government launches.

The advent of SpaceX’s Falcon 9 rocket has provided competition to the EELVs for the first time since ULA took over operations of the Atlas and Delta lines, and in response to this and political concerns regarding Russian components on the Atlas V – particularly the RD-180 first stage engine – United Launch Alliance has begun development of a new-generation rocket named Vulcan which will eventually replace both the Atlas V and Delta IV.

ULA has already announced plans to phase out the Delta IV, beginning with the Medium configurations over the next few years. The Delta IV Heavy – which is presently the only rocket capable of carrying the NRO’s optical reconnaissance and geostationary signals intelligence satellites – will remain in service until another vehicle can take over its duties and has passed the appropriate certification.

The next Delta mission is expected to make use of the Delta IV Heavy, deploying NROL-37 which is likely to be an Orion signals intelligence satellite bound for geostationary orbit. This flight, which will also be the next mission for the National Reconnaissance Office, is currently scheduled for mid-May.

Before then, United Launch Alliance will use Atlas V rockets to launch a Cygnus resupply mission to the International Space Station in March and a MUOS communications satellite for the US Navy in early May.

The launch of NROL-45 was the tenth of 2016 worldwide and the third from the United States.

(Images: via ULA, NASASpaceFlight.com’s Derrick Stamos and L2 – including work via L2 artist Nathan Koga – The full hi-res gallery of Nathan’s (SpaceX Dragon to MCT, SLS, Commercial Crew and more) L2 images can be *found here*)

(Click here: http://www.nasaspaceflight.com/l2/ – to view how you can support NSF’s running costs and access the best space flight content on the entire internet)

NROL-55
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Two secret National Reconnaissance Office/U.S. Navy ocean surveillance satellites are set for launch from Vandenberg Air Force Base, Ca. Oct. 8 on the NRO-55 flight that will also deploy 13 advanced technology CubeSats.

The military space mission is planned for liftoff from Space Launch Complex-3E at 5:49 a.m. PDT (8:49 a.m. EDT) on a United Launch Alliance (ULA) Atlas-V 401 launch vehicle with no solid rocket boosters. The launch window is expected to run until 6:30 a.m. PDT.

Bookmark our “NROL-55 Launch Tracker” for regular updates and LIVE COVERAGE on Oct. 8 beginning at 5:29 a.m. PDT.
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As with all NRO Atlas-V flights the highly classified intelligence payload will be propelled to orbit by an 860,000 lb. thrust Russian Energomash RD-180 engine, which continues to raise concern within the Air Force and Atlas-V users like the NRO.

The flight is also carrying 9 NRO and 4 NASA CubeSats mounted in a deployment box on the aft end of the Centaur upper stage.

The 15 satellites in total will be deployed into a 1,000 x 1,200 km. (621 x 745) mile orbit, inclined 63.4 degrees to the equator.

The two NRO satellites weigh nearly 4 tons each.

The mission is to replace two similar National Ocean Surveillance System (NOSS) spacecraft launched from Cape Canaveral on Feb 3, 2005 on the final Atlas-III rocket before the shift to the Atlas-V Evolved Expendable Launch Vehicle (EELV).
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The first generation of U.S. Naval Research Center NOSS satellites were launched in groups of three starting in 1976, according to Ted Molczan, an expert Canadian astrodynamist. A second generation of triple spacecraft missions was active during the 80s and 90s, followed in 2001 by the start of third generation spacecraft launch in pairs instead of triplets, said Molczan.

The pairs of NOSS satellites fly in a “space combat spread” type formation dozens of miles apart laterally and with the second satellite in trail of the first. This is so radio transmissions from ships reach the satellites at different times enabling a constant track of a ship’s direction and speed. It allows the Navy’s top secret ship tracking intelligence center to track the position and intentions of ships of every nationality around the globe.
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The NRO/NASA CubeSats are being flown on NRO-55 under the Government Rideshare Advanced Concepts (GRACE) experiment, which on this mission involves 9 NRO and 4 NASA advanced technology satellites.

They are all mounted in a Naval Post Graduate School deployment box mounted to the aft bulkhead of the rocket’s Centaur upper stage.

The NRO CubeSats are:

– AeroCube-5C and AeroCube-7: Developed by the Aerospace Corp., these two 3 lb. satellites will demonstrate tracking technologies, optical communications and laser communications.

– SNaP-3: Developed by the Army Space and Missile Defense Center involves three CubeSats each nearly 10 lb. in mass. They are to develop user-software defined radios to provide line of sight communications for disadvantage users in remote areas.

– PropCube: Developed by Tyvak Nano Satellite Systems LLC, the two 2 lb. CubeSats will perform dual frequency ionospheric calibration measurements.

– SINOD-D: Developed by SRI, the two 4.5 lb. CubeSats will demonstrate software defined radio communications.
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The NASA sponsored CubeSats are:

– ARC-1: The 2.2 lb. Alaska Research CubeSat-1, developed by the University of Alaska, Fairbanks, will measure its own thermal and vibration environment during launch and also increase the technology readiness level on its attitude control determination system, as well as its high bandwidth communications system.

– BisonSat: Under development for 4 yrs. at Montana’s Salish Kootenai College on the Flathead Indian Reservation, the 2.2 lb. satellite has been training students on the design, construction, test and operation of space hardware by using a specially designed camera to calculate land cover classification, cloud cover, and cloud height measurements.
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– AMSAT Fox-1: Developed by the AMSAT Corp., the 2.2 lb. satellite has an FM amateur radio voice repeater that will provide easy portable satellite communications opportunities for amateur radio operators world wide. The satellite will also test a micro electro mechanical (MEMS) gyro and a low energy proton experiment.
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– LMRST-Sat: Developed by Jet Propulsion Laboratory the 6.6 lb. Low Mass Radio Transponder Satellite will demonstrate the transponder in Earth orbit to raise its technology readiness level.

NROL-55 will be the 58th Atlas-V mission for ULA since the vehicle’s inaugural launch in 2002. The mission is ULA’s 10th of 2015 and 101st since the company was founded in December 2006.

NROL-61
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Identifying the classified NROL-61 Satellite
NROL-61 is the third mission of the U.S. National Reconnaissance Office in 2016, lifting into orbit a classified satellite to support the agency’s spy satellite programs.
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The NRO is an intelligence agency tasked with the design, construction and operation of all U.S. reconnaissance satellites as well as the distribution of satellite intelligence to other agencies including signals intelligence for the NSA, image reconnaissance to the NGA and measurement and signatures intelligence to the DIA. Established back in 1961, the NRO is shrouded in great secrecy and most of its active programs are highly classified with declassification only possible decades after the end of specific programs.

As an intelligence agency, the NRO makes great efforts to keep its activities secret, therefore the identity of any and all NRO satellites are classified. However, it is possible to identify the nature of satellites by analyzing their launch trajectory as available in navigational warnings to mariners and pilots, the type of launch vehicle to constrain an approximate satellite mass and the launch window to assess possible target orbits.

Typically, NRO satellites are tracked in their secret orbits within a few days by a worldwide network of satellite observers, revealing from where they operate which usually provides a good idea of a satellite’s purpose.

In the recent past, some cases were very easy to solve while others could only be narrowed down to a number of candidates. NROL-61 is one of the more mysterious missions:
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The NROL-61 payload uses an Atlas V 421 launch vehicle with a four-meter payload fairing and two Solid Rocket Boosters – making use of the Atlas V’s ability to be tailored to specific payload needs by adding boosters to the vehicle’s Common Core Booster to achieve the required performance to the target orbit.
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To date, Atlas V 421 has flown five times, lifting the first two Wideband Global Satcom satellites in 2007 and 2009, a pair of commercial communications satellites in 2008 and ’15, and NASA’s MMS mission in 2015, probing the secret’s of Earth’s magnetosphere. No NRO mission utilized this version of the Atlas V – clearly suggesting this to be a new type of satellite or a modified follow-on to an existing project.

Another oddity found in the launch vehicle configuration is the payload fairing flown on this mission – the Extra Extended Payload Fairing (XEPF) that is 13.8 meters long, providing a larger payload volume for particularly tall birds.

The most revealing clue helping in the identification of the payload is the 99-degree launch azimuth to be flown by Atlas V – departing Cape Canaveral to the east-south-east. This is the standard departure path for either Geostationary Transfer Orbit missions or direct Geosynchronous Insertions – ruling out a delivery to a highly elliptical Molniya orbit inclined 57 to 63.4° or any inclined Low Earth Orbit.

The most likely candidate for NROL-61 is it being the first in the fourth generation of the Satellite Data System, a fleet of relay satellites operated in high orbits to deliver data from reconnaissance satellites in lower orbits including the flagship KH-11 image reconnaissance craft, enabling transmission of imagery in near-real time to support operational applications.

Declassified Image of Early SDS Satellite – Credit: National Reconnaissance Office
Declassified Image of Early SDS Satellite – Credit: National Reconnaissance Office

The Satellite Data System, also known by its code name Quasar, saw its first launch in 1976 using a Titan-3 rocket. The first generation satellites – at least seven of which were launched until 1987 – weighed in at under one metric ton and operated from a Molniya-type orbit with their apogee locked over the northern hemisphere to enable data relay from the polar regions.

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In addition to satellite data relay, the SDS craft support communications to U.S. Air Force aircraft in the northern regions and connect the Air Force Satellite Control Network ground stations.

The second generation of Quasar satellites was inaugurated in 1989.

Three were launched on the Space Shuttle while the last one, lofted in 1996, used a Titan-4 rocket. It is believed that the second generation SDS carried an infrared early warning system for the detection of ballistic missile launches with the satellites weighing in at around three metric tons. Three of the SDS-2 satellites were delivered to Molniya-type orbits with a 39,700-Kilometer apogee while one entered a Geostationary Orbit.
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The third generation of SDS satellites incorporates a combination of satellites in highly elliptical Molniya orbits for coverage of the northern regions and spacecraft in Geostationary Orbit to deliver round-the-clock global coverage.

The replenishment of Molniya satellites apparently ended in 2007, likely marking the transition to a purely GEO-based system. Improvements in technology have allowed GEO satellites to service high-latitude regions, though polar coverage is still a challenge when only using satellites in GEO.

Eight third generation SDS satellites were launched between 1998 and 2014 with a launch cadence of around two to three years to keep the constellation at operational strength. The satellites used Atlas-IIAS, Atlas-V 401 and Delta IV M+(4,2) launch vehicles.

NROL-61 likely represents the first in the next generation of SDS satellites – based on the type of launch vehicle, its ascent trajectory and the timing of the launch two years and two months after the most recent Quasar launch, fitting the overall replenishment speed of the satellites.

The use of the more-powerful Atlas V 421 indicates the next generation of SDS satellites has gained mass compared to their predecessors. With the help of its twin boosters, Atlas V 421 can lift 6,890 Kilograms into Geostationary Transfer Orbit compared to 4,750kg for the 401 version without any boosters – indicating that the satellites may have gained as much as two metric tons in mass or are aiming for a higher-energy insertion orbit closer to their operational GEO.

Previous SDS launches utilized the Long Payload Fairing of the Atlas V rocket measuring 12 meters in length, suggesting the next generation of SDS satellites requires more space inside the fairing, most likely for more or larger communications antennas.
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The NROL-61 mission also continues a trend of interesting mission insignia being chosen by the National Reconnaissance Office that is known to sometimes drop some hints regarding the payload’s identity into the patch design.

Prominently featured in the patch is an ascending Atlas V launch vehicle with an anthropomorphized lizard or dragon riding shotgun on the vehicle’s payload fairing. A pillar of smoke from the rocket’s business end connects the ascending vehicle with its Cape Canaveral launch site, though the trajectory is not representative of the actual launch azimuth.

The mission patch features four stars – one larger than the other three which may suggest this launch represents the fourth generation of a particular satellite program – which would fit the SDS theory.
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However, the possibility of this being a one-off or completely new satellite operating from GEO can not be ruled out until the spacecraft’s behavior in orbit is known.

A worldwide network of satellite trackers will attempt to spot the NROL-61 satellite after launch and track its climb into Geostationary Orbit and possible moves it will make to enter its operational spot above the Earth to provide further proof of the satellite’s identity.

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The launch patch, a second icon produced for the mission, shows the Earth surrounded by a mesh of overlapping arch shapes forming a twelve-pointed star.

The outline of the patch itself has thirteen edges, likely representing the fact that Thursday’s launch is the thirteenth Atlas V mission for the NRO.

The NRO have released two cartoon images featuring Spike ahead of the launch, which appear to form part of an outreach exercise to increase interest in spaceflight amongst children.

The Atlas V that carried out the NROL-61 mission had the tail number AV-065.

NROL-79
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NRO really knows how to make badass patches!

Identifying the classified NROL-79 Satellite:

The United States National Reconnaissance Office is an intelligence agency tasked with the design, construction and operation of all U.S. reconnaissance satellites and delivers satellite intelligence to other intelligence agencies including signals intelligence for the NSA, image reconnaissance data to the NGA and measurement & signature intelligence to the DIA. Established in 1961, the NRO has been shrouded in great secrecy and its existence as an agency was only first acknowledged in the early 1990s.

As an intelligence agency, the NRO goes through great lengths to keep its activities secret, therefore the identity of all NRO satellites is classified. However, it is possible to identify the nature of satellites taking into account their launch site, launch window, launch vehicle type and ascent path. Sometimes, hints can be found in mission logos and, after launch, most satellites are typically tracked in orbit by a worldwide network of observers, revealing from where they operate, and often what they are tasked with.

Some cases are easier to solve while other NRO missions can only be narrowed down to a number of candidates. There is not much of any doubt as to the identity of NROL-79 as the eighth mission supporting the third generation of the the Naval Ocean Surveillance System, NOSS for short.
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NROL-79 utilizes the base version of the Atlas V (401) and launches from the U.S. West Coast which already narrows the identification of the mission to those requiring a polar or retrograde orbit. The three known NRO satellites to launch on Atlas from Vandenberg are NOSS (Naval Ocean Surveillance System), Trumpet Electronic Intelligence Satellites and FIA-Radar imaging satellites. Trumpet satellites have used Atlas V 411 and Delta IV M+ (4,2) rockets while FIA-Radar launches have to date used the larger Atlas V 501 and Delta IV M+ (5,2) vehicles. As this launch uses the 401 version of Atlas, NOSS is the most likely option since all of the most recent NOSS missions used the most basic Atlas V version.

Additional evidence comes through the timing of the mission as it was found that NOSS 3 satellite pairs are being replaced at a ten-year cadence as shown of the NOSS 3-5 launch in 2011 that replaced the 3-1 pair which orbited for just over ten years and drifted out of formation eight months after the replacement was sent up. The same pattern was repeated with the 3-6 pair the replaced 3-2 after nine and a half years in orbit and NOSS 3-7 was orbited ten and a half years after the 3-5 pair to become its replacement. The launch of NOSS 8-3 comes just under ten years after the NOSS 3-4 mission was lifted into orbit by an Atlas V rocket, however, requiring the satellites to correct their orbits after a premature shutdown of the Centaur upper stage.
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The Naval Ocean Surveillance Satellite project dates back to 1976 when the first generation of NOSS satellites, flying in triplet formations, was first launched – taking over from the now declassified Poppy Program that served as a NOSS precursor, launching four satellites in 1971.

The purpose of the NOSS satellites is the location of foreign ships and aircraft to deliver tactical information to United States intelligence agencies and the military. To accomplish their task of locating and monitoring ships/aircraft, the NOSS satellites employ the time-difference-of-arrival by tracking the vehicle’s radio transmissions. A calculation of position requires multiple satellites to fly in a precise formation to calculate the relative geometry between the satellites and the ship through the time difference in the arrival of the signal – not dissimilar to the Global Positioning System where a ground-based receiver requires multiple satellite signals to calculate its position.

NOSS went through three generations of satellites, implementing technical improvements and mass reduction. The first generation of satellites was launched between 1976 and 1987 followed by the second generation of NOSS triplets that was launched between 1990 and 1996. The third generation, making its debut in 2001, provided a surprise as the NOSS satellite triplets were reduced to pairs of satellites.

Additionally, the change from triplets to pairs also came with a change in the orbital setup of the satellites that had been launched to 1,110-Kilometer orbits at an inclination of 63.4° since their conception.

The newer satellites entered orbits around 1,000 by 1,200km, 63.4° to avoid a phenomenon discovered during the initial operations of NOSS – a gradual increase in orbital eccentricity due to perturbations caused by Earth’s gravitational field. The new setup, as detailed by satellite tracker Ted Molczan, launches the satellites into an orbit with an argument of perigee near 180 degrees. The argument of perigee shifts gradually to 90 degrees and with that, the orbit becomes circular at 1,100 Kilometers around four years after launch. The orbital precession then continues and the orbit becomes elliptical again, reaching 1,000 by 1,200 km again after eight years, likely the operational life of the satellites.

Technical details on the NOSS satellites are only sparsely available. They are built by Lockheed Martin and operated by the U.S. Navy under the code name ‘Intruder’ according to information leaked out in 2013. Stationkeeping between the satellites is likely accomplished by modifying their ballistic coefficients through the use of external panels that can adjust the area faced to the ram direction where minute drag effects can be utilized to slowly modify the orbit. Reportedly, the two-spacecraft NOSS stack launching on Atlas V has a mass of around 6.5 metric tons.

The Naval Ocean Surveillance Satellites in their initial triplet constellation were closely copied by the Chinese. Triplets of Yaogan satellites, China’s primary military reconnaissance satellite constellation, were launched starting in 2010 and entered orbits similar to the first two NOSS generations.

FUENTES / SOURCES :

NROL-45

https://www.nasaspaceflight.com/2016/02/ula-delta-iv-nrol-45-launch/

http://www.satnews.com/story.php?number=13616385

http://spaceflight101.com/delta-iv-nrol-45/nrol-45-satellite/

http://www.spaceflightinsider.com/space-centers/vafb/ula-delta-iv-with-classified-nro-payload-set-for-feb-10-launch-from-vandenberg/

https://spaceflightnow.com/2016/02/09/photos-nrol-45-payload-fitted-atop-delta-4-for-launch/

NROL-55
http://www.spaceflightinsider.com/missions/defense/ula-prepares-to-send-classified-nrol-55-spacecraft-to-orbit/
http://www.americaspace.com/2015/10/07/thursdays-atlas-v-nro-55-launch-to-revitalize-ocean-surveillance-assets-and-multiple-space-technologies/
http://www.spaceflightinsider.com/missions/defense/vulcans-hammer-united-launch-alliance-lofts-secretive-nrol-55-mission/

NROL-61
http://spaceflight101.com/atlas-v-nrol-61/nrol-61-satellite/
http://www.conowego.pl/aktualnosci/wczoraj-w-kosmos-wystrzelono-tajemniczego-szpiegowskiego-satelite-18730/
http://www.spaceref.com/news/viewsr.html?pid=49149
https://www.nasaspaceflight.com/2016/07/atlas-v-launch-nrol-61-reconnaissance-satellite/

NROL-79

http://spaceflight101.com/atlas-v-nrol-79/nrol-79-satellite/

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