Star (rocket stage)

Star-37

TE-M-364
Country of origin	United States
Date	1963-present
Application	Upper stage/Spacecraft propulsion
Predecessor	Star 27
Successor	Star 48
Status	Active
Solid-fuel motor
Configuration
Chamber	1
Performance
Thrust (vac.)	33.600 kN (7,554 lbf)
Isp (vac.)	(161,512 N•s/kg)
Dimensions
Length	2.27 m (7.44 ft)
Diameter	0.66 m (2.16 ft)
Dry weight	113 kg (249 lb)
Used in
Thor (rocket family), Delta (rocket family), upper stage

The Star is a family of American solid-fuel rocket motor used by many space propulsion and launch vehicle stages. It is used almost exclusively as an upper stage.

Star 24

The Star 24 (TE-M-640) is a solid apogee kick motor, first qualified in 1973.^[1] It burns an 86% solids carboxyl-terminated polybutadiene (CTPB) fuel.^[1][2]

Thiokol Star-24 family^[1]

Star 27

A Star-27 kick motor with nozzle for IBEX

The Star 27 is a solid apogee kick motor.^[3] It burns HTPB fuel with an average erosion rate of 0.0011 inches per second.^[4][3] When used on the Pegasus air-launch rocket payloads are capable of leaving Earth orbit.^[3] A modified version, designated Star 27H,^[5] was used in the launch of the IBEX spacecraft.^[6] The spacecraft had a mass of 105 kg by itself and together with its Star 27 motor, 462 kg.^[6] The Star 27H helped it get to a higher orbit, beyond Earth's magnetosphere.^[6]

Star 37

The Star 37 was first used as the engine for the Thor-Burner upper stage. The Burner I used the Thiokol FW-4 (TE 364-1) engine and the Burner 2 used the Thiokol (TE-M-364-2).^[7]

The "-37" designation refers to the approximate diameter of the fuel casing in inches; Thiokol had also manufactured other motors such as the Star-40 and Star 48. Internally, Thiokol's designation was TE-M-364 for early versions, TE-M-714 for later ones, and TE-M-783 for a special HTPB model used for FLTSATCOM launches.
Subtypes are given one or more letter suffixes after the diameter number, or a trailing number (i.e., "-2") after the internal designation. Not surprisingly, the "T" prefix stands for Thiokol, and the following letter refers to the company division that developed the rocket motor. In this case, "M" refers to the Magna, UT Division. "E" refers to the Elkton, MD division.

The Star 37FM rocket motor was developed and qualified for use as an apogee kick motor on FLTSATCOM. The motor is a replacement for the Star 37E Delta, which has been discontinued. The Nozzle assembly uses a 3D carbon-carbon throat and a carbon-phenolic exit cone. Maximum propellant weight is 2350 pounds, while the motor has been qualified for propellant off-loading to 2257 pounds.
The Star 37XFP rocket motor has been qualified as the orbit insertion motor for Rockwell International's (now Boeing) Global Positioning Satellite (GPS), and as the apogee motor for the RCA SATCOM Ku-Band satellite. The Star 37XFP motor can be used as a replacement for the Star 37F motor, which has been discontinued.

A spin-stabilized or thrust-vectoring version of Star 37 is used as the final stage of the Minotaur V launch vehicle.^[8][9]

Thiokol Star-37 family

Star 48

The Star 48 is a type of solid rocket motor developed primarily by Thiokol Propulsion, and is now manufactured by Orbital ATK, which purchased Thiokol in 2001.^[10]

The "48" designation refers to the approximate diameter of the fuel casing in inches; Thiokol had also manufactured other motors such as the Star 37 and Star 30. Internally, Thiokol's designation was TE-M-711 for early versions, and TE-M-799 for later ones. Subtypes are given one or more letter suffixes after the diameter number, or a trailing number (i.e., "-2") after the internal designation. Not surprisingly, the "T" prefix stands for Thiokol, and the following letter refers to the company division that developed the rocket motor. In this case, "E" refers to the Elkton, MD division and the "M" stands for motor.

The most common use of the Star 48 was as the final stage of the Delta II launch vehicles. Other launchers have also incorporated the motor, but with lower frequency. In such usage, the complete stage (motor plus accessories) is referred to as the Payload Assist Module (PAM), as the Shuttle could only take satellites to low Earth orbit. Because geostationary orbit is much more lucrative, the additional stage was needed for the final leg of the journey. On such missions, the stage is spin-stabilized. A turntable, mounted in the shuttle payload bay or atop the previous Delta stage, spun the PAM and payload to approximately 60 rpm prior to release.

Usually after motor burnout and just prior to satellite release the PAM is de-spun using a yo-yo de-spin technique.

A non-spinning, thrust-vectoring version of the Star 48 is available ("Star 48BV"), but much less common. A thrust-vectoring Star 48 is the final stage of the Minotaur IV+ launch vehicle.

A Star 48 motor used in the 3rd stage of the New Horizons probe was the first part of the New Horizons mission to reach Jupiter, crossing Pluto's orbit in 2015 at a distance of 200 million kilometers.^[11]

Saudi inspectors at the crash site of a Star-48 Payload Assist Module in January, 2001.

A Star 48 Payload Assist Module that had been used to launch a GPS satellite in 1993 crashed in the Saudi Arabian desert in January 2001, after its orbit decayed. The unit did not burn up on reentry and was positively identified on the ground.^[12]

In 2013 a Star 48GXV was tested for the Solar Probe Plus mission as the upper stage on a Atlas V 551 vehicle,^[13] but the development was cancelled, in favor of a Delta IV Heavy / Star 48BV combination.^[14]

Related development

Burner upper stages

The Burner and Burner 2 rocket stages have been used as upper stages of launch vehicles such as the Thor and Delta since 1965. Burner II was a launch vehicle upper stage developed by Boeing for the Air Force Space Systems Division. It was the first solid-fuel upper stage with full control and guidance capability developed for general space applications.

In March 1964, the DMSP program office approved plans to develop a more powerful Thor Burner 2 launch vehicle. Burner 2 used a Thiokol Star 37B motor (TE-M-364-2). Star 37, from which Star 37B was derived, had originally been developed to serve as the Surveyor lunar lander retro-rocket. Star 37B weighed 718 kg loaded and produced about 4.59 tonnes of thrust for 42 seconds. The Burner 2 stage was fitted with 3-axis control by Boeing, allowing it to coast without spin stabilization after separating from Thor.^[15]

Burner II was a launch vehicle upper stage developed by Boeing for the Air Force Space Systems Division. It was the first solid-fuel upper stage with full control and guidance capability developed for general space applications. Burner II was designed for use with the Thor booster, but was readily adapted for use on the complete range of standard launch vehicles. Its general assignment was to place small- and medium size payloads into orbit. The Burner II motor, guidance system and reaction control system were integrated to provide attitude stability and precise control of flight rate and burnout velocity for orbital injection and earth-escape missions. Boeing had delivered 8 flight vehicles under its original contract. Under terms of a follow-on contract, it built 6 additional flight models.

In addition to use on Delta family rockets, Burner 2 / Star 37 stages have been used on both Atlas and Titan rockets.^[16]

Solid propellant rocket stage. Loaded/empty mass 774/116 kg. Thrust 43.55 kN. Vacuum specific impulse 285 seconds. Thiokol solid rocket engine. 43.5 kN. Total impulse 161,512 kgf s. Motor propellant mass fraction 0.899. Isp=260s. First flight 1963. Thrust (sl): 33.600 kN (7,554 lbf). Thrust (sl): 3,428 kgf.

Gross mass: 621 kg (1,369 lb). Unfuelled mass: 63 kg (138 lb). Height: 0.84 m (2.75 ft). Diameter: 0.66 m (2.16 ft). Thrust: 43.50 kN (9,779 lbf). Specific impulse: 260 s. Specific impulse sea level: 220 s. Burn time: 42 s. Number: 180

References

• Star 37 motors

External links

• Astronautix - Star 27
• Solid Propellant Rocket Fundamentals (Pages 417-418)