Processing of laser altimeter time-of-flight measurements to geodetic coordinates

Xiao, Hu; Stark, Alexander; Steinbrügge, Gregor; Hußmann, H.; Oberst, J.

doi:10.1007/s00190-020-01467-4

Cited by 10 publications

(24 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…From the brief description of the MOLA PEDR geolocation process [33], we inferred that they have accounted for the motion of the spacecraft during times-of-flight, but have not mentioned anything about pointing aberration or other forms of pointing correction. Thus, we applied the SMM geolocation model with Mars as the observer for the recomputation [21]:…”

Section: Methodsmentioning

confidence: 99%

“…Given the trajectory and attitude of the spacecraft, pointing alignment of the laser altimeter, and rotational model of the target body, the time-of-flight measurements can be converted to surface coordinates in the body-fixed reference frame of the target body, i.e., the geolocation process. In a previous work, we presented a consistent and systematic formulation of three commonly-used geolocation models with increasing complexity: Static Model (SM), Spacecraft Motion Model (SMM), and Pointing Aberration Model (PAM) [21]. Furthermore, the Special Relativity Model (SRM) is proposed to take care of the special relativity effects, which have been analytically demonstrated to be equivalent to PAM given some assumptions.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, the Special Relativity Model (SRM) is proposed to take care of the special relativity effects, which have been analytically demonstrated to be equivalent to PAM given some assumptions. These various models were then compared taking Mars Orbiter Laser Altimeter (MOLA) and Mercury Laser Altimeter (MLA) profiles as examples [21].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Recomputation and Updating of MOLA Geolocation

et al. 2022

Self Cite

View full text Add to dashboard Cite

The Mars Orbiter Laser Altimeter (MOLA) Precision Experiment Data Records (PEDR) serve as the geodetic reference of Mars. However, these MOLA footprints were geolocated using outdated auxiliary information that dates back to 2003. In this study, we recompute the MOLA PEDR footprint locations and investigate the impact of the updated spacecraft orbit model and Mars rotational model on MOLA’s geolocation. We observe quasi-exponential increases near the poles of up to 30 m in the recomputation residuals for the nadir profiles. Meanwhile, we demonstrate that limitations exist in the stored MOLA PEDR attitude records, which can shift the footprint up to hundreds of meters laterally and several meters radially. The usage of the Navigation and Ancillary Information Facility (NAIF)-archived attitude information instead can circumvent this issue and avoid the approximation errors due to discrete samplings of the attitude information used in geolocation by the PEDR dataset. These approximation errors can be up to 60 m laterally and 1 m radially amid controlled spacecraft maneuvers. Furthermore, the incorporation of the updated spacecraft orbit and Mars rotational model can shift the MOLA profiles up to 200 m laterally and 0.5 m radially, which are much larger in magnitude than the aforementioned dramatic increases near the poles. However, the shifted locations of the reprocessed profiles are significantly inconsistent with the PEDR profiles after the global cross-over analysis.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Recomputation and Updating of MOLA Geolocation

et al. 2022

Self Cite

View full text Add to dashboard Cite

show abstract

“…Furthermore, we take into account the pointing aberration induced by special relativity. For the nadir-pointing profiles, this factor can lead to lateral shifts of less than 5 m and radial ones of less than 5 cm, whereas these values can be as high as 10 m and 25 m, respectively, for the intermittently acquired profiles with off-nadir pointing angles up to 35° (Xiao et al, 2021). These off-nadir profiles were acquired by commanding MGS to roll off-nadir >10°to fill the gaps beyond the orbital limits of ∼87°S/N, and have amounted to more than 100 throughout the mission.…”

Section: State Of the Art Reprocessingmentioning

confidence: 99%

“…Furthermore, the intersection angles of profiles forming these non-polar cross-overs can be shallow, which makes them vulnerable to cross-track components of profile lateral shifts due to residual errors. Even limited cross-track displacements are capable of shifting these intersection points dramatically upwards or downwards along the near-parallel profiles, compromising the measured cross-over height differences (Xiao et al, 2021, see also Sec. 6.2).…”

Section: Potential Applicationsmentioning

confidence: 99%

Prospects for Mapping Temporal Height Variations of the Seasonal CO2 Snow/Ice Caps at the Martian Poles by Co-registration of MOLA Profiles

Xiao,

Stark,

Steinbrügge

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

We investigate the feasibility and demonstrate the merits of using Mars Orbiter Laser Altimeter (MOLA) profiles to retrieve seasonal height variations of CO 2 snow/ice cap in Mars' polar areas by applying a co-registration strategy. We present a prototype analysis on the research region of [85.75°S, 86.25°S, 300°E, 330°E] that is located on the residual south polar cap. Our method comprises the recomputation of MOLA footprint coordinates with an updated Mars Global Surveyor (MGS) ephemeris and a revised Mars rotation model. The reprocessed MOLA dataset at the South Pole of Mars (poleward of 78°S) is then self-registered to form a coherent reference digital terrain model (DTM). We co-register segments of reprocessed MOLA profiles to the self-registered MOLA reference DTM to obtain the temporal height differences at either footprints or cross-overs.Subsequently, a two-step Regional Pseudo Cross-over Adjustment (RPCA) procedure is proposed and applied to post-correct the aforementioned temporal height differences for a temporal systematic bias and other residual errors. These pseudo cross-overs are formed by profile pairs that do not necessarily intersect, but are connected through the underlaying DTM. Finally, CO 2 snow/ice temporal height variation is obtained by median-filtering those post-corrected temporal height differences. The precision of the derived height change time series is ∼4.9 cm. The peak-to-peak height variation is estimated to be ∼2 m. In addition, a pronounced "pit" (transient height accumulation) of ∼0.5 m in magnitude centered at L s = 210°in southern spring is observed. The proposed method opens the possibility to map the seasonal CO 2 snow/ice height variations at the entire North and South polar regions of Mars.

show abstract