Solar Wind Samples

Solar Wind Links

Purpose

Genesis Samples Catalog

Pre-Launch Preparations

Collector Design

Contamination Control Planning

Cleaning Space- Bound Hardware

Flight Timeline

Recovery in Utah

Field Recovery

Recovery Processing

Collector Status

How to Request Samples

Science Results

Introduction: Genesis launched in 2001 with 271 whole and 30 half hexagonally-shaped collectors mounted on 5 arrays, comprised of 9 materials described in [1]. The array collectors were damaged during re-entry impact in Utah in 2004 [2], breaking into many smaller pieces and dust. A compilation of the number and approximate size of the fragments recovered was compiled from notes made during the field packaging performed in the Class 10,000 cleanroom at Utah Test and Training Range [3].

Array Collectors as Launched: Specific arrays, with collectors of a thickness unique to that array, were exposed to capture separate samples of the bulk solar wind (700 ìm thick collectors), the transient wind associated with coronal mass ejections (650 ìm thick collectors), the high speed solar wind from coronal holes (600 ìm thick collectors), and the lowspeed interstream solar wind (550 ìm thick collectors). Each array carried hexagons mounted typically as shown in Figure 1, although material layout and amount varied in each array. Each of the 4 deployable arrays carried 54 whole hexagons and 6 half-hexagons. Each hexagon measured 10.2 cm maximum dimension, an area of 65 cm2. The non-deployable array carried 55 whole and 6 halves.

Utah Recovery Fragment Handling: A very great portion of the fragments packaged in Utah were retrieved from the interior of the canister, and thus were dry and had little exposure to lakebed mud (Figure 2). Most fragments are visibly dusty, and much of this dust appears to be powdered silicon and germanium. The packaging process in Utah had the primary goal of stabilizing the fragments so that further surface scratching was prevented. This stabilization was accomplished by placing individual fragments inside polystyrene vials, the diameter of which prevented the solar-winded surface from touching the vial walls. A knit polyester dunnage was used to immobilize the fragments. Another method used the light tack of “cleanroom post-it notes” to immobilize fragments from the back side.

Array Collectors Fragments Recovered: Nearly 10,000 fragments were individually stabilized. Fragments > 1cm were imaged and described (Figure 3). A substantial portion of fragments > 5mm was also imaged and decribed. Eleven different processors, working from from Septemebr 8 to Oct 4, 2004, produced the data compiled in Table 2. Sizing was done by the longest dimension of the fragment. Because it was difficult to visually distinguish among FZ silicon, CZ silicon and diamond on silicon, these three categories are grouped together. Nevertheless this information is useful for developing a strategy for preliminary assessment, sample storage and allocation. It became apparent early in the processing that silicon and germanium were preferentially broken into smaller pieces during impact. One whole hexagon and 3 half hexagons survived intact – all are sapphire-based collectors. All of the silicon and germanium collectors were oriented in the (100) direction, whereas the sapphirebased collectors have no continuous cleavage plane. Figure 4 shows this difference in size distribution clearly.

A comparison of 10 to 25 mm fragment composition to pre-flight source material for the fragments supports depletion of cm-sized non-sapphire-based collectors in the recovered fragments (Table 3).

Acknowledgements: The following people worked 12-hour, physically-demanding days to characterize and package the 10,000 fragments summarized in this paper: Judy Allton, Ron Bastien, Don Burnett, Claire Dardano, Amy Jurewicz, Karen McNamara, Carol Schwarz, Eileen Stansbery, Lisa Vidonic, Jack Warren, and Dottie Woolum. The Genesis team also received outstanding response from JSC and JPL/Caltech support personnel who quickly sent supplies and containers.

References:

[1] Jurewicz A. J. G. et al. (2002) Spa. Sci. Rev., 105, 535-560 (2002).

[2] McNamara K. M. et al. (2005), Lunar and Planetary Science Conference XXXVI (2004)

[3] E.K. Stansbery et al. (2005), Lunar and Planetary Science Conference XXXVI