Montenbruck O.,German Space Operations Center |
Swatschina P.,German Space Operations Center |
Markgraf M.,German Space Operations Center |
Santandrea S.,European Space Agency |
And 2 more authors.
GPS Solutions | Year: 2012
Within the PROBA-2 microsatellite mission, a miniaturized single-frequency GPS receiver based on commercial-off-the-shelf (COTS) technology is employed for onboard navigation and timing. A rapid electronic fuse protects against destructive single-event latch-ups (SEL) and enables a quasi-continuous receiver operation despite the inherent sensitivity to space radiation. While limited to single-frequency C/A-code tracking with a narrow-band frontend, the receiver is able to provide precision navigation services through processing of raw GPS measurements on ground as well as a built-in real-time navigation system. In both cases, ionospheric path delays are eliminated through a combination of L1 pseudorange and carrier phase measurements, which also offers a factor-of-two noise reduction relative to code-only processing. By comparison with satellite laser ranging (SLR) measurements, a 0. 3-m (3D rms) accuracy is demonstrated for the PROBA-2 reduced dynamic orbit determinations using post-processed GPS orbit and clock products. Furthermore, the experimental onboard navigation system is shown to provide real-time position information with a 3D rms accuracy of about 1 m, which notably outperforms the specification of the Standard Positioning Service (SPS). In view of their lower hardware complexity, mass budget and power requirements as well as the reduced interference susceptibility, legacy C/A-code receivers can thus provide an attractive alternative to dual-frequency receivers even for demanding navigation applications in low Earth orbit. © 2011 Springer-Verlag.
Galardini D.,Redu Center |
Sandberg J.,Redu Center
European Space Agency Bulletin | Year: 2011
Artemis went into service in 2008 at short notice during the first ATV mission when NASA's TDRSS link was unavailable after Hurricane Ilk struck. Since then, the satellite has provided regular data relay services to the CNES SPOT-4 Earth observation satellite using the SILEX high data-rate optical link, and a low data-rate link in S-band. After preparation, testing, and implementing new in-flight software, the ion propulsion technology payload on board Artemis was used to push the satellite to its final destination. Correct operation of the closed-loop tracking system for the Ka-band inter-orbit antenna was also demonstrated, which acquired a signal transmitted from Redu and maintained the link automatically while Artemis drifted slowly across the sky. Artemis has delivered a service availability higher than 99% over its operational life, including cases when there was conflict between service requests of users.
Pirard T.,Redu Center |
Galardini D.,Redu Center |
Guillaume S.,Redu Center |
Leonard C.,Redu Center
European Space Agency Bulletin | Year: 2013
The Redu station, ESA's center in the Belgian Ardennes, plays a discreet but essential role in Europe's space effort. Close to half a century ago, the picturesque village of Redu first came to the attention of Europe's then fledgling space community. It was planned to locate a European satellite tracking station a mere stone's throw from the village church and main square, bringing the tranquil Ardennes countryside to the forefront of the conquest of space. Since 1968, Redu has been part of Estrack, formerly ESRO's and now ESA's satellite tracking and control network. It has participated in many European science missions, relaying signals from ESRO's scientific satellites in orbit to the European Space Operations Center (ESOC) in Darmstadt, Germany. In 1975, ESA was formed by the merger of ESRO and the European Launcher Development Organization, the latter having been tasked with designing and producing a launcher system.