SOHO soldiers on – and a Falcon flies

Peter Bond reviews current space activity and finds some new starts – including an asteroid sample return mission – and some stalwarts continuing their work – SOHO and Chandra among them.     

Refinements and revelations

Peter Bond summmarizes recent discoveries about Martian radiation, possible new forms of matter and a sooty black comet – not to mention the nearly new Hubble Space Telescope.     

Density-induced settling of tephra through organic lakesediments

Tephras are often used in paleolimnology and other stratigraphicapplications as a chronostratigraphic marker. Where analytical errors inradiocarbon or other dating methods make precise comparison between sitesdifficult, tephras provide an absolute stratigraphic reference that can be usedto assess the relative ages of events across a region. Applications oftephrochronology typically make the assumption that a tephra is deposited atwhat was the top of the stratigraphic sequence at the time of deposition, andthat the contact between the tephra and underlying sediments is anisochron. This paper presents evidence from two lakes in western Canadawhich suggest that tephras may be very mobile within the sedimentary column,particularly in low-density organic lake sediments. Analysis of sedimentcores from Copper Lake, Alberta, suggest that the 6730 BP Mazama tephra moveddown-core by the equivalent of more than 3000 years. A vertical exposureof the Holocene sediments from Doal Lake, Yukon Territory, reveals that the1200 BP White River (WR) tephra, found throughout the southern Yukon, moveddown-sequence through organic lake sediments, to a stratum dating toapproximately 10,000 BP, creating conformable tephra beds at that level. Thistype of stratigraphic displacement has important consequences for the use oftephrochronology in lakes and other soft-sediment environments andunderscores the importance of properly identifying tephras and criticallyassessing their stratigraphic context within a lake core.     

Propagation of local errors in the solutions of the differential equations for orbital elements

The propagation of errors in the solutions of the differential equations for the orbital elements of perturbed two-body motion is investigated. It is shown that the error in the time-element grows linearly for differential equations for orbital elements when only perturbations are present on the right-hand side, cubically for formulations which have a two-body term on the right-hand side, and linearly for formulations based upon extended phase space Hamiltonians.     

Hello Mars, goodbye Hubble?

Successes at Mars make the promise of more money for space exploration appealing, but will other projects pay the price? Peter Bond reports.     

Analytical satelite theory in extended phase space

In the present note we show how a simple canonical transformation in extended phase space makes the transition from classical Delaunay elements to the Scheifele variables. We do not use spherical coordinates or Hamilton-Jacobi theory. The meaning of the new variables is briefly explained, especially the use of the true anomaly as one of the variables.     

Auroral surges in southern hemisphere

All-sky camera photographs from Mawson have been used to determine the speeds of westward travelling auroral surges over Antarctica. The results indicate surge speeds comparable to the largest recorded for northern hemisphere surges.     

Ups and downs

Cluster goes up but will planetary programmes go down? Peter Bond reports on space mission plans and achievements.