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Nandi, Sumita

Publications and source records attributed to Nandi, Sumita.

25 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS2008

Orbit Determination for the 2007 Mars Phoenix Lander

The Phoenix mission is designed to study the arctic region of Mars. To achieve this goal, the spacecraft must be delivered to a narrow corridor at the top of the Martian atmosphere, which is approximately 20 km wide. This paper will discuss the details of the Phoenix orbit determination process and the effort to reduce errors below the level necessary to achieve successful atmospheric entry at Mars. Emphasis will be placed on properly modeling forces that perturb the spacecraft trajectory and the errors and uncertainties associated with those forces. Orbit determination covariance analysis strongly influenced mission operations scenarios, which were chosen to minimize errors and associated uncertainties.

Ryne, Mark S.↗
NASA NTRS2006

On-Orbit Maneuver Calibrations for the Stardust Spacecraft

The Stardust spacecraft, launched February 7, 1999, successfully delivered its sample return capsule to the Utah Test and Training Range on January 15, 2006. The entry maneuver strategy included a trajectory correction at entry minus 10 days (TCM18) targeted to entry with the inclusion of a final biased fixed direction maneuver at entry minus 29 hours (TCM19). To meet the stringent entry targeting requirements necessary for human safety and capsule integrity, a campaign of maneuver calibrations were undertaken in summers of 2003 and 2005 to improve performance for both maneuvers. The results of the calibration program are reported here. The in-flight calibrations included a series of several turns to various final attitudes via deadband walks about each of the three spacecraft axes, as well as 12 in-place burns with magnitudes between 0.5 and 1.0 m/s, the range initially expected for TCM19. The turn and burn calibrations as well as the performance of TCM 17, 18 and 19 are discussed.

maneuver↗
NASA NTRS2006

Modeling of Deadbanding DV for the Stardust Earth Return: Calibration, Analysis, Prediction and Performance

On January 15th, 2006, 0556 UTC, the Stardust spacecraft released a 42-kg Sample Return Canister (SRC) along a trajectory intended to impact a target on the Air Force Utah Test and Training Range (UTTR), near Dugway, Utah. Assurances of a successful SRC delivery to UTTR depended on identifying (and mitigating, if possible) a myriad of error sources. These sources included atmospheric effects, maneuver execution, Orbit Determination (OD) uncertainties and (Delta)V induced by the firing of the unbalanced Reaction Control System (RCS) thrusters needed for deadband attitude control. Every mm/s in prediction error at the TCM-19 epoch would amount to missing the target by approximately one kilometer. This paper will describe the work performed in analyzing and predicting the levels of (Delta)V caused by the attitude deadbanding, as well as prediction performance.

Stardust↗
NASA NTRS2004

Nozomi Earth swingby orbit determination

This paper describes the Jet Propulsion Laboratory effort to navigate Nozomi, in conjunction with Japan's Institute of Space and Astronauticaal Science, past two Earth swingbys using differential tracking techniques to successfully place the spacecraft on a trajectory reaching Mars in December 2003.

Nandi, Sumita↗
NASA NTRS1993

A demonstration of TDRS orbit determination using differential tracking observables from GPS ground receivers

A Global Positioning System (GPS) flight receiver provides a means of precisely determining orbits for satellites in low to moderate altitude orbits. Above 5000 km altitude, however, relatively few GPS satellites are visible. We present a new approach to orbit determination for satellites at higher altitudes. Modification of GPS ground receivers enables a beacon from the orbiter to be tracked simultaneously with GPS data. The orbit accuracy expected from this GPS-like tracking (GLT) technique in principle could be comparable to accuracies of GPS orbits. Present-day GPS orbit quality from a daily semi-automated analysis system at the Jet Propulsion Laboratory is at the 30 - 50 cm level: expected accuracies for orbiters with GLT are calculated to be in the few-meter range for altitudes up to 100000 km. For geosynchronous satellites, however, there are unique challenges due to geometrical limitations and to the lack of strong dynamical signature in tracking data. We examine two approaches for tracking Tracking and Data Relay Satellites (TDRS) geostationary orbiters. One uses GLT with a global network; the other relies on a small `connected element' ground network with a distributed clock for short baseline differential carrier phase (SB Delta Phi). In priciple, both could meet 50-m TDRS operational requirements. However there are practical difficulties with either pure GLT or SB Delta Phi tracking schemes for present-day TDRS satellites. We describe an experiment planned for late 1993 which will combine aspects of both GLT and SB Delta Phi to demonstrate a new approach for tracking TDRS which offers a number of operationally convenient and attractive features. The TDRS demo will in effect ba a proof of concept experiment for both the GLT and SB Delta Phi approaches to tracking spacecraft.

Lichten, Stephen M.↗