Laboratory reflectance measurements of analogues to “dirty” ice surfaces on atmosphereless solar system bodies

Stephens, John; Gustafson, B. Å. S.

doi:10.1016/0019-1035(91)90151-i

Cited by 12 publications

(8 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Laboratory experiments with sublimating ice-refractory particle mixtures show color variations caused by restructuring that may well parallel the changes observed here (Stephens & Gustafson 1991). The muted colors (both slightly red and slightly blue) of these laboratory mantles are similar to the colors of the cometary nuclei and the candidate dead comets.…”

Section: Discussionsupporting

confidence: 77%

From Kuiper Belt Object to Cometary Nucleus: The Missing Ultrared Matter

Jewitt

2002

The Astronomical Journal

206

240

View full text Add to dashboard Cite

We combine new and published data to show that the optical color distributions of cometary nuclei and Kuiper belt objects (KBOs) are significantly different. The nuclei are, as a group, bluer than the KBOs, indicating that the surface chemical and/or physical properties of the two types of bodies are different. Objects in the dynamically intermediate Centaur class have optical colors like those of KBOs, while the color distribution of candidate dead comets is indistinguishable from that of the cometary nuclei. We infer that the surfaces of KBOs are modified upon entry to the inner solar system. We consider several mechanisms and conclude that the color change is most likely caused by the rapid burial of ancient surface materials exposed in the Kuiper belt. The distinctive, ultrared material that is present on the surfaces of some KBOs is absent on the cometary nuclei.

show abstract

Section: Discussionsupporting

confidence: 77%

From Kuiper Belt Object to Cometary Nucleus: The Missing Ultrared Matter

Jewitt

2002

The Astronomical Journal

206

240

View full text Add to dashboard Cite

show abstract

“…Additionally, COSIMA collected small, apparently compact particles which are also flat, but the resolution is insufficient to determine if they are single grains, or indeed aggregates themselves. On the other hand, cluster-cluster aggregation with rotating grains can form elongated structures with very high aspect ratios 17 , and laboratory experiments have produced dust "flakes" 18 .…”

Section: ) It Is Not Yet Clear If This Is An Intrinsic Property Of mentioning

confidence: 99%

Aggregate dust particles at comet 67P/Churyumov–Gerasimenko

Bentley

Schmied

Mannel

et al. 2016

Nature

165

121

View full text Add to dashboard Cite

Norway * These authors contributed equally to this workComets are believed to preserve almost pristine dust particles, thus providing a unique sample of the properties of the early solar nebula. The microscopic properties of this dust play a key role in particle aggregation during Solar System formation 1,2 . Prior to Rosetta cometary dust was considered to comprise irregular, fluffy agglomerates based on interpretation of remote observations in the visible and infrared [3][4][5][6] MIDAS, the Micro-Imaging Dust Analysis System 13,14 , is the first spaceborne atomic force microscope (AFM) and a unique instrument designed to measure the size, shape, texture and microstructure of cometary dust. Flying on the Rosetta spacecraft, it collects dust on sticky targets during passive exposures and images its 3D topography with an unprecedented nanometre to micrometre resolution 13 .Cometary dust was first collected in mid-November 2014. In this work we focus on particles collected from then until the end of February 2015. The collected particles cover a range of sizes from tens of micrometres down to a few 100 nanometres, and have various morphologies, from single grains to aggregate particles with different packing densities. Five examples are presented here. Figure 1 shows topographic images (height fields) of three particles (A, B and C). Particles A and C will be referred to as compact, since their sub-units (hereafter grains) are tightly packed, and B appears to be a homogeneous grain. The next example (D) is also a compact particle scanned with a higher lateral resolution of 80 nm (Fig. 2) -a factor four better than the previous scan. The final particle (E), presented in Fig. 3, is best described as a loosely packed "fluffy" aggregate comprising many grains. Detailed collection times and geometries for all particles can be found in Extended Data Fig. 1-3.Aided by the 3D nature of the data, individual grains can be identified, as shown in Fig. 1b, Fig. 2b and 1.09 −0.25 +0.01 µm in size, again similar to the grains in A-C. However, the higher resolution reveals that this micrometre-sized particle is itself an aggregate of smaller units; seven grains can be resolved, with sizes ranging from 260 −120 +50 nm to 540 −250 +20 nm. The visible part of particle E has a maximum extent of 14 µm in X and 37 µm in the Y direction. Analysis of its component grains (Fig. 3d) shows sizes in the range from 0.58 −0.20 +0.15 to 2.57 −0.51 +004 µm with the grain heights ranging between 0.2 µm and 3 µm with 90% smaller than 1.7 µm. These measurements are the first evidence for a continuation of the aggregate nature of dust particles below the size range observed by COSIMA (10s-100s micrometres) 15 .Particle E also shows a morphology strongly reminiscent of stratospheric chondritic porous (CP) IDPs, long suspected of having a cometary origin. This link is consistent with observations by COSIMA for larger dust particles, which also measured similar compositions for dust at 67P and IDPs 15,16 . One notable difference to IDPs is the extre...

show abstract

“…Although the last experiment may simulate a situation where the silicate is hidden by carbon, our calculations show that coating itself cannot make the spectra substantially red-particle size is very important. For example, clustering can reverse the spectral slope, and in fact Stephens and Gustafson (1991) gave this mechanism high priority-carbon dust formed after evaporation of an icy component is somewhat brighter and more red than the same unmanipulated carbon dust. This shows both that the sublimation process itself increases the degree of clumping in the material left behind and that a homogeneous medium is slightly darker and bluer than a heterogeneous medium.…”

Section: Visual Geometric Albedo and Photometric Colorsmentioning

confidence: 97%

“…13 and 14. Stephens and Gustafson (1991) also speculated that their dust mantle analogues perhaps should have been redder if the carbon was coating the silicate, instead of being mechanically mixed. A reddening during sublimation was indeed observed when mixtures without silicate were studied.…”

Section: Visual Geometric Albedo and Photometric Colorsmentioning

confidence: 97%