Engineering Papers⌕ Search

Engineering topics

Graat, Eric

Publications and source records attributed to Graat, Eric.

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2021

Maven Navigation Support of the Mars 2020 Perseverance Entry, Descent and Landing

Through three years of maneuvering, the MAVEN orbiter was able to support the Mars 2020 (M2020) Perseverance Entry, Descent and Landing (EDL), while also changing to a more relay friendly orbit and preserving a mission lifetime through 2030. The synchronization of the MAVEN orbit for M2020 EDL will be reviewed, followed by a description of the MAVEN phasing for EDL. Poten-tial concerns that arose from large density variations will be discussed, along with the interfaces between MAVEN and M2020.

Kangas, Julie↗
NASA NTRS2020

Navigation Design and Operations of Maven Aerobraking

This paper describes the operational design and execution of the MAVEN aerobraking phase at Mars from a Navigation Team perspective. MAVEN was designed to perform atmospheric science in a ~150x6200 km altitude elliptical orbit. After the primary science mission, it was decided that MAVEN should circularize its orbit, as much as feasible from a spacecraft and mission standpoint, to better support relay operations with the landers. As a result, MAVEN performed aerobraking in the first half of 2019 to reduce its orbit to ~150x4500 km altitude. Although MAVEN did not decrease its altitude as low as previous aerobraking missions, it had several unique challenges. Science observations continued to be taken during aerobraking, requiring dramatically better Navigation accuracies than typical for such phases. Furthermore, continuous DSN coverage with 2-way Doppler data was not available. So, with 40% less Doppler data, Navigation had to meet prediction accuracies which were an order of magnitude smaller than in previous aerobraking operations. Spacecraft accelerometer data was included in Navigation analyses in order to meet these requirements.

Jakosky, Bruce↗
NASA NTRS2017

50,000 Laps Around Mars: Navigating the Mars Reconnaissance Orbiter Through the Extended Missions (January 2009 - March 2017)

Orbiting Mars since March 2006, the Mars Reconnaissance Orbiter (MRO) spacecraft continues to perform valuable science observations, provide telecommunication relay for surface assets, and characterize landing sites for future missions. Previous papers reported on the navigation of MRO from interplanetary cruise through the end of the Primary Science Phase (PSP) in December 2008 and on maneuvers performed through November 2016. This paper highlights the navigation of MRO from January 2009 through its 50,000th orbit around Mars on March 27, 2017, an eight-year period covering the Extended Science Phase, the first three extended missions, and a portion of the fourth extended mission which began on October 1, 2016. Since the beginning of the PSP in November 2006, MRO’s navigation performance has continued to exceed expectations. Over that period of time, the mission has returned over 300 terabytes of data.

Schulze, William↗
NASA NTRS2017

Mars Reconnaissance Orbiter Navigation Strategy for the ExoMars Schiaparelli EDM Lander Mission

The Mars Reconnaissance Orbiter (MRO) had planned to provide surface relay support for the brief mission of the ExoMars Schiaparelli EDM lander on Mars in October 2016. Launched with the Trace Gas Orbiter (TGO) in March 2016, Schiaparelli and TGO composed the first part of the ExoMars program. To place MRO directly overhead on its third overflight of the Schiaparelli landing site, two propulsive maneuvers were performed starting three months prior to Shiaparelli’s arrival at Mars. This paper documents the maneuver strategy employed by the MRO Navigation Team to support the Schiaparelli overflight campaign.

Schulze, William B.↗
NASA NTRS2016

MAVEN Navigation During the First Mars Year of the Science Mission

The Mars Atmosphere and Volatile Evolution mission (MAVEN) is the first mission devoted to studying the Martian atmosphere. From a Navigation perspective it is unique in that science is performed at near aerobraking altitudes. This results in the requirements on Navigation trajectory accuracy requirements which are an order of magnitude tighter than those of aerobraking phases on previous missions. Navigation experiences with the Mars atmosphere are described as they pertain to Navigation models, trajectory reconstructions, trajectory predictions, density corridor control, and collision avoidance of other bodies around Mars.

Demcak, Stuart↗
NASA NTRS2015

A Journey with MOM

In late 2013, the Indian Space Research Organization (ISRO) launched its "Mars Orbiter Mission" (MOM). ISRO engaged NASA's Jet Propulsion Laboratory (JPL) for navigation services to support ISRO's objectives of MOM achieving and maintaining Mars orbit. The navigation support included planning, documentation, testing, orbit determination, maneuver design /analysis, and tracking data analysis. Several of MOM's attributes had an impact on navigation processes, e.g., S -band telecommunications, Earth Orbit Phase maneuvers, and frequent angular momentum desaturation s (AMDs). The primary source of tracking data was NASA/ JPL's Deep Space Network (DSN); JPL also conducted a performance assessment of Indian Deep Space Network (IDSN) tracking data. Planning for the Mars Orbit Insertion (MOI) was complicated by a pressure regulator failure that created uncertainty regarding MOM's main engine and raised potential planetary protection issues. A successful main engine test late on approach resolved these issues; it was quickly followed by a successful MOI on 24-September - 2014 at 02:00 UTC. Less than a month later, Comet Siding Spring's Mars flyby necessitated plans to minimize potential spacecraft damage. At the time of this writing, MOM's orbital operations continue, and plans to extend JPL 's support are in progress. This paper covers the JPL 's support of MOM through the Comet Siding Spring event.

Mars orbiter↗
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 NTRS2008

Mars Reconnaissance Orbiter Navigation During the Primary Science Phase

The Mars Reconnaissance Orbiter began science operations in November 2006, with a suite of seven instruments and investigations, some of which required navigation accuracies much better than previous Mars missions. This paper describes the driving performance requirements levied on Navigation and how well those requirements have been met thus far. Trending analyses that have a direct impact on the Navigation performance, such as atmospheric bias determination, are covered in detail, as well as dynamic models, estimation strategy, tracking data reduction techniques, and residual noise.

MRO↗
NASA NTRS2007

Mars Reconnaissance Orbiter Interplanetary Cruise Navigation

Carrying six science instruments and three engineering payloads, the Mars Reconnaissance Orbiter (MRO) is the first mission in a low Mars orbit to characterize the surface, subsurface, and atmospheric properties with unprecedented detail. After a seven-month interplanetary cruise, MRO arrived at Mars executing a 1.0 km/s Mars Orbit Insertion (MOI) maneuver. MRO achieved a 430 km periapsis altitude with the final orbit solution indicating that only 10 km was attributable to navigation prediction error. With the last interplanetary maneuver performed four months before MOI, this was a significant accomplishment. This paper describes the navigation analyses and results during the 210-day interplanetary cruise. As of August 2007 MRO has returned more than 18 Terabits of scientific data in support of the objectives set by the Mars Exploration Program (MEP). The robust and exceptional interplanetary navigation performance paved the way for a successful MRO mission.

You, Tung-Han↗
NASA NTRS2004

Mars Exploration Rover Cruise Orbit Determination

The Mars Exploration Rover project consisted of two missions (MER-A: spirit rover and MER-B: opportunity rover) that launched spacecraft on June 10, 2003, and July 8, 2003, respectively. The spacecraft arrived at Mars approximately seven months later on January 4, 2004, and January 24, 2004. These spacecraft needed to be precisely navigated to a Mars atmospheric entry flight path angle of -11.5 deg +/-0.12 deg (3(sigma)) for MER-A and +/-0.14 deg (3(sigma)) for MER-B in order to satisfy the landing site delivery requirements. The orbit determination task of the navigation team needed to accurately determine the trajectory of the spacecraft, predict the trajectory to Mars atmospheric entry, and account for all possible errors sources so that the each spacecraft could be correctly targeted using five trajectory corrections along the way. This paper describes the orbit determination analysis which allowed MER-A to be targeted using only four trajectory correction maneuvers to an entry flight path angle of -11.49 deg +/-O.010 deg (3(sigma)) and MER-B to be targeted using only three trajectory correction maneuvers to an entry flight path angle of -11.47 +/-0.021 deg(3(sigma)).

navigation↗
NASA NTRS2004

Mars Exploration Rover cruise orbit determination

This paper will describe the results of the orbit determination process for each mission, MER-A and MER-B, during their cruise phase to Mars ending with there final approach to Mars atmospheric entry.

navigation↗
NASA NTRS2004

Mars Exploration Rovers orbit determination filter strategy

The successful delivery of the Mars Exploration Rover (MER) landers to well with in the boundaries of their surface target areas in January of 2004 was the culmination of years of orbit determination analysis. The process began with a careful consideration of the filter parameters used for pre-launch covariance studies, and continued with the refinement of the filter after launch based on operational experience. At the same time, tools were developed to run a plethora of variations around the nominal filter and anlyze the results in ways that had never been previously attempted for an interplanetary mission. In addition to the achieved sub-kilometer Mars B plane orbit determination knowledge, the filter strategy and process responded to unexpected error sources by both detecting them and proving robust. All these facets of the MER orbit determination filter strategy are described in this paper.

orbit determination↗