The Small Deep Space Transponder is a transponder designed by

JPL The Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center in the City of La Cañada Flintridge, California, United States. Founded in the 1930s by Caltech researchers, JPL is owned by NASA an ...

specifically for deep space probes. It unifies a number of communication functions - receiver, command detector, telemetry modulator, exciters, beacon tone generator, and control functions - into one 3-kg package. The SDST is designed to handle

X band The X band is the designation for a band of frequencies in the microwave radio region of the electromagnetic spectrum. In some cases, such as in communication engineering, the frequency range of the X band is rather indefinitely set at approxim ...

uplink and both

and Ka band downlink. JPL estimates that performing the same functions with separate units (as was done previously) requires over twice the mass and 4 or 5 individual subassemblies.

Functions

The capabilities of the SDST include: *X-band receiver/downconverter capable of carrier tracking at or below −156 dBm. *Command detector unit function. *Telemetry modulation function. *X- and Ka-band exciters. *Beacon mode operation. *Coherent and noncoherent operation choice. *X- and Ka-band ranging. *Differential one-way ranging (DOR) for both X-band and Ka-band. *Command and Data Handling (C&DH) communication via MIL-STD-1553. *Data interface via EIA-422 (also known as RS-422). *External ports for temperature sensors. *External port for an analog signal.

Missions

SDST has been used in the following missions: * Deep Space 1. This was a developmental mission that used the transponder for the first time, as part of an effort to qualify new technologies for flight. *'' Deep Impact'' *'' Dawn'' used a pair of SDSTs * Mars Exploration Rovers * Mars Reconnaissance Orbiter *

MESSENGER ''MESSENGER'' was a NASA robotic space probe that orbited the planet Mercury between 2011 and 2015, studying Mercury's chemical composition, geology, and magnetic field. The name is a backronym for "Mercury Surface, Space Environment, Geoche ...

STEREO Stereophonic sound, or more commonly stereo, is a method of sound reproduction that recreates a multi-directional, 3-dimensional audible perspective. This is usually achieved by using two independent audio channels through a configuration ...

Spitzer Space Telescope The Spitzer Space Telescope, formerly the Space Infrared Telescope Facility (SIRTF), was an infrared space telescope launched in 2003. Operations ended on 30 January 2020. Spitzer was the third space telescope dedicated to infrared astronomy, f ...

*A pair of SDSTs were used in the cruise stage of Phoenix (spacecraft). The lander used only UHF communication. *The Mars Science Laboratory includes two SDSTs, one on the descent stage and one on the lander itself. The SDST on the descent stage was the main transponder for the cruise and landing portions of the flight, with the SDST on the rover as a backup. The descent stage crashed after lowering the rover, and the SDST on the lander became the active transponder. As many tightly constrained, high-performance systems, the SDST has a number of idiosyncrasies in operation. However, as the ''Dawn'' telecom 'lessons learned' section points out, the use of common hardware such as the SDST allows knowledge of these characteristics from previous projects. For cubesat missions, the SDST is too big, heavy, and power-hungry. For these missions, the Iris transponder could be considered instead.

References

{{authority control Jet Propulsion Laboratory Mars Science Laboratory Spitzer Space Telescope Mars Reconnaissance Orbiter

Functions

Missions

See also

References