Evidence for dust accumulation just outside the orbit of Venus Options

[Paolo]

New science from old data (Helios 2 in this case)
http://arxiv.org/abs/0708.0912

[cndwrld]

Thanks for posting this, Paolo.

I have tried multiple times to access the site, but get timeouts. I'll keep trying, but if anyone knows something about it, please let me know.

[Paolo]

This is the abstract

Evidence for dust accumulation just outside the orbit of Venus
Authors: Ch. Leinert, B. Moster
Abstract: To contribute to the knowledge of dynamics of interplanetary dust we are searching for structures in the spatial distribution of interplanetary dust near the orbit of Venus. To this end we study the radial gradient of zodiacal light brightness, as observed by the zodiacal light photometer on board the Helios space probes on several orbits from 1975 to 1979. The cleanest data result from Helios B (= Helios 2) launched in January 1976. With respect to the general increase of zodiacal light brightness towards the Sun, the data show an excess brightness of a few percent for positions of the Helios space probe just outside the orbit of Venus. We consider this as evidence for a dust ring associated with the orbit of Venus, somewhat similar to that found earlier along the Earth's orbit.


And you can try one of the many mirrors of arxiv. I use the Italian one: http://it.arxiv.org/abs/0708.0912

[cndwrld]

Thanks, Paolo. The Italian one worked.

[tasp]

Granted, I lead a sheltered life, but this is absolutely the first scientific finding I have ever seen attributed to the Helios craft.

[Paolo]

INLINE QUOTE REMOVED - DOUG

Actually, the two Helios produced a wealth of results, but they were not as exciting as those of a planetary probe. If you look on the NASA abstract service you will find hundreds of Helios-related publication.
Moreover, in 1985, the German space agency and NASA published a book to commemorate the 10th year of the launch of Helios 1 which included detailed summaries of the findings of each instrument.

[tasp]

Thanx for the info.

To revise and extend my remark;

It has always been a wonder to me that since their launch the Helios mission (to my knowledge) has never been written up in Science News, Astonomy, Sky and Telescope, Discovery, Scientific American, Final Frontier, The Planetary Report, Mercury, Ad Astra, Popular Science, National Geophraphic, or Reader's Digest.

Just curious that the international cooperation angle, and that they were launched on big ol' Titan III Cs, never garnered more than the 'yeah they were launched' notice in the popular space/science/astronomy mainline publications.

Further curiousity:

Had Helios 1 or 2 employed a gravitational encounter with Venus (like Mariner 10) how much closer to the sun could they (heat protection system willing) have traveled ??

[edstrick]

Heat Protection system was NOT willing, as I understand. #1 established the accuracy of the thermal protection design and #2 was launched into an orbit that pushed the design's limits <and the launch ability of a Titan 3 Centaur + kick stage, I think>

I'm somewhat surprised that there never was a follow on mission that went in to 0.1 AU or less using Venus flybys, but the goal since the late 70's was the solar probe corona flythrough mission. Another mission, that like Mars Network Science, is on everybody's want-to-fly list but never gets high enough to get the dollar$ or euro$.

[Paolo]

Had Helios 1 or 2 employed a gravitational encounter with Venus (like Mariner 10) how much closer to the sun could they (heat protection system willing) have traveled ??

I have been recently researching for an historical article on the European close solar flyby project of the 70s (which I have submitted to the JBIS). It turns out that there were studies of the possibility of using Venus flybys instead of a Jupiter flyby to establish a solar grazing orbit.
At the time it was estimated that it would take 4 years and 5 flybys of the planet just to reduce the perihelion distance to 0.09 AU (against a single Jupiter flyby for a 0.02 AU orbit).
Also note that there were at least two proposals to reuse the Helios bus. One was a relativity mission (SOREL, discussed in detail in my article), that was to approach to within 0.29 AU of the Sun and the other was the Helios C 1980 flyby of comet Encke.