On April 28, 1997, NASA Headquarters faxed national radio personality (with an estimated 15 million listeners ...) Art Bell, asking for his help "in setting the record straight on the subject of Hubble Space Telescopes observations of Comet Hale-Bopp ... discussed by a guest on one of your recent programs [emphasis added] ..." The co-signers of the NASA fax were "Dr. Ed Weiler, Hubble Program Scientist"; and "Don Savage, Public Affairs Officer, Office of Space Science, NASA Headquarters."

During a subsequent conversation with Art Bell (after clarifying to our mutual satisfaction the identity of this mysterious "recent guest" ...), Art suggested that he invite Weiler, as "official Hubble Program Scientist," to "debate" Tom Van Flandern and myself re the scientific disagreements we have had with "official NASA plans vis a vis Hale-Bopp."

NASA emphatically refused.

In lieu of such a "debate" (which would have been patterned after the previous one-on-one "Art Bell discussions" with NASA Apollo 14 astronaut, Ed Mitchell), Art then agreed to a two-hour interview along, with a suitable "official NASA representative": NASA responded by designating Don Savage, from NASA Headquarters, and Ray Villard, from NASA's "Space Telescope Science Institute," as Art's "official NASA guests" -- to be interviewed May 1-2, 1997. The proposed subject: the contents of the "Art Bell NASA fax."

Neither NASA representative is a "Hubble scientist," responsible either for specific experiments on-board the Hubble Telescope, or, NASA policies around it. It is for this reason that, when Art then asked Tom Van Flandern and me to follow as his guests for the remaining three broadcast hours of that night, Tom and I respectfully declined; nothing will be served by "beating up" on these two NASA representatives, after they are gone. Our objections to what is (or is NOT) currently occurring vis a vis NASA and Hale-Bopp, lies with those in charge of NASA officials such as Dr. Weiler, Administrator Dan Goldin, etc. -- not with those merely representing NASA's policies, such as Savage or Villard.

Thus, in lieu of this hoped-for "one-on-one debate" with Dr. Weiler, Dr. Van Flandern and I have decided to annotate NASA's original "Art Bell fax" (below) -- to provide documented evidence, across the World Wide Web, of the major mis-statements it contains. After posting, it will be up to Art's listeners and other concerned American citizens to act ...

The Fax

The Response

NASA: "...your guest said that Hubble has not been used to observe Hale-Bopp, or perhaps it had, but we were 'hiding' the images..."

Hoagland: In fact, initially, we stated precisely the opposite: that Hubble (according to official NASA press releases) had last been used to observe Hale-Bopp on October 17, 1996... over 7 months before its closest (thus, highest value) passage to the sun and Earth, on April 1, 1997. NASA's release of March 27, 1997 (see below) affirms this fact.





This is a series of Hubble Space Telescope observations of the region around the nucleus of Hale-Bopp, taken on eight different dates since September 1995. They chronicle changes in the evolution of the nucleus as it moves ever closer to, and is warmed by, the sun.

The first picture in the sequence, seen at upper left shows a strong dust outburst on the comet that occurred when it was beyond the orbit of Jupiter. Images in the Fall of 1996 show multiple jets that are presumably connected to the activation of multiple vents on the surface of the nucleus.

In these false color images, taken with the Wide Field and Planetary Camera 2, the faintest regions are black, the brightest regions are white, and intermediate intensities are represented by different levels of red. All images are processed at the same spatial scale of 280 miles per pixel (470 kilometers), so the solid nucleus, no larger than 25 miles across, is far below Hubble's resolution.

Credit: Harold Weaver (Johns Hopkins University) and NASA

Hoagland (cont'd): In terms of the second point ... NASA "hiding" Hale-Bopp data ... examine closely the official Comet images (above) and their description. This is a series acquired by the Hubble Telescope, spanning over a year -- during which time the Comet traveled almost a quarter of a billion miles closer to the Earth. But notice carefully: NASA (for some inexplicable reason) has reduced the resolution of the latest (closest!) images to match the low resolution of the farthest -- thus, literally throwing away (hiding..?) the significantly increasing resolution available to Hubble on October 17th, 1996. For God's sake, why?

"Hiding" of official NASA data: proven.

Unaddressed, of course, was the other question which we asked that evening: if later, far higher-resolution Hale-Bopp Hubble images have indeed been taken ... where are they now? And, if they haven't been taken -- of the brightest, most scientifically spectacular, unique Comet of this Century -- for God's sake, why not?

NASA: "Hubble's major contribution has been to accurately measure the diameter of the [Hale-Bopp] nucleus (about 25 miles)."

Hoagland: Wrong.

In Dr. Hal Weaver's own official NASA press release ( below), he bases his PRELIMINARY estimate of ~25 miles for the Hale-Bopp nucleus on the few Hubble images (~2) he was able to acquire in September and October, 1995 -- when the Comet was still beyond the orbiter of Jupiter, over half a billion miles away. This was more than a year and a half before Hale-Bopp's March 22, 1997 closest approach to Earth.


Comet Hale-Bopp (C/1995 O1)
News and Views

(Updated: 15 December 1995)

News Flash!!!

Our current best PRELIMINARY estimate for the effective diameter of Hale-Bopp's nucleus is: 40 kilometers (= 25 miles)

If the latter value is correct, then the nucleus of Hale-Bopp is approximately four times larger than that of comet Halley.

However, we must emphasize that measuring Hale-Bopp's size is extremely difficult, even with HST's superb spatial resolution. If you want to learn more about how we derived the above number, you can go directly to the figure from which we estimate the nuclear size . The figure caption describes what assumptions were made and why our estimate could be wrong. We have added a new figure that illustrates a little better HST's possible "photometric" detection of the nucleus.

We should also point out that there is not necessarily a direct relationship between the size of the nucleus and the strength of its activity. We learned from studying comet P/Halley and other periodic comets that, generally, only a small portion of the nuclear surface is "active". A small nucleus that is active over most of its surface area can emit more gas and dust into the coma than a much larger nucleus that is almost completely covered over by an insulating mantle of rubble. Thus, even if our preliminary estimate of the nuclear size is correct, that does not necessarily ensure that the comet will put on a spectacular visual display in early 1997.

On the other hand, a large nucleus (as indicated by the HST observations), and the huge gas and dust production rates at large heliocentric distances (as measured during the ground-based observations of CO and CN), certainly increase the odds that Hale-Bopp will not disappoint us.

Above: The above composite compares the Hubble Space Telescope (HST) images of comet Hale-Bopp taken in September (left) and October (right). In both cases the nucleus is centered in the frame, celestial North is straight up, celestial East is to the left, and each frame is 10 arcsec across. CLICK on the image to see a larger and improved version.

During September we caught Hale-Bopp only about 60 hours after an outburst, and the image shows a jet and spiral pattern emanating from the nucleus. The image from October was taken during a "quiescent" phase and barely shows any structure in the inner coma. The image in this latter case had to be strongly stretched in order to see anything (which explains why the image looks grainier than the September image). The inner coma during October is clearly elongated nearly due North. There is a very faint patch of enhanced brightness approximately 3.5 arcsec North of the nucleus, which is undoubtedly the remnant of the outburst that occurred on October 13th (i.e., 10 days prior to the HST observations).

If you like you can go directly to the October 1995 report .

This WWW page is designed to provide late-breaking information on the newly-discovered comet Hale-Bopp (C/1995 O1) and is being provided as a service by the Applied Research Corporation (ARC) .

Particular emphasis will be placed on results from the Hubble Space Telescope (HST) . Eleven orbits of HST observing time have been allocated to a Cycle 5 Target of Opportunity program, and the first observations were attempted during 26-27 September 1995.


Some of the material below is based on preliminary analyses of recently acquired data. Please do not quote results from this page in any scientific or professional context without first contacting Hal Weaver . Feel free to use the information and images from this page for public outreach activities. However, these data are generally not suitable for scientific purposes without further information.

Hoagland (cont'd): Question -- if Dr. Weaver's own cautionary estimate was only based on these two images (above) -- with no later, much-higher resolution Hubble imagery involved -- how can NASA now claim that "Hubble's major contribution" has been to "accurately measure" Hale-Bopp's nucleus?

Where is this new, crucial Hubble data -- if this statement is, in fact, not mere "Hubble hype?"

NASA: "... Hubble's pointing restriction [with in 50 degrees of the sun] can be relaxed somewhat under certain unusual circumstances, and Dr. Weaver had requested observations of Hale-Bopp during the first two weeks in March. However, a detailed analysis showed that Hale-Bopp would be visible to Hubble for about 5 minutes while the observatory was in Earth shadow (and, thus, protected from sunlight). This was not enough time to make observations and slew the telescope back into a safe configuration prior to emerging into potentially-damaging sunlight [emphasis added] ..."

Hoagland: A few weeks ago, Dr. Van Flandern and I independently calculated a "ball park" figure for how much time Hubble would actually have to view Hale-Bopp, given the astronomical restriction of "observing from Earth's shadow." The time-frame we selected was "a week or two, centered around April 1st." The resulting total observing time (we calculated) was also in the "4-5 minute" range -- taking into allowance the angle between Hale-Bopp and the sun, and the "total slewing time" required to point Hubble at Hale-Bopp from the initially safe "parked" 50-degree avoidance position, after entering the shadow.

It is the second half of NASA's statement that's erronous.

Given that approximately ~ 45 minutes of every Hubble orbit is spent in the shadow (at this position in Earth's orbit around the sun: within a week or two of the Spring Equinox), our calculations in dicated that well over 30 minutes (after Hale-Bopp had "set" for Hubble) would be available, until "spacecraft sunrise," to slew Hubble away from its solar pointing attitude -- back to a "safe" angle. And, only about 20 minutes would be required for the "slew."

We even considered the ultimate back-up: Hubble is equipped with an "aperture door" -- in essence, a giant electrically operated lens cap -- designed to be slammed shut in case the telescope is accidently pointed at the sun. The door shuts in fractions of a second -- either automatically (via on-board sensor/computer command), or by direct human override from Goddard. If the telescope was too slow (after the Hale-Bopp observations) in slewing to a "safe" position (relative to the direction of the sun), the "ultimate backup" would be to simply close the door!

Thus, in philosophy, as well as in detail, the prime NASA "excuse" cited in the "Art Bell fax" -- for not aggressively pursuing "once in a lifetime," close-in Hale-Bopp observations with Hubble -- is simply, demonstrably ... wrong.

NASA: "...Even if observations were attempted, no spectroscopy was possible because new instruments installed during the servicing mission (only a few weeks earlier) were not yet ready to make astronomical observations. Thus the prime scientific motivation for Hubble observations, searching for new chemical species in the comet, could not be achieved..."

Hoagland: First: what "brilliant" NASA manager -- with a two-year warning on the impending apparition of the most spectacular Comet of the Century (after all, Hale-Bopp was initially spotted where a comet had never been seen before -- almost 200 million miles beyond Jupiter's orbit) -- carefully scheduled the Hubble Repair Mission just before Hale-Bopp would reach the inner solar system..?

Second: who said "searching for new chemical species..." with the Hubble Space Telescope was "the prime scientific motivation for Hubble observations..." of Hale-Bopp?!

If Hubble's prime contribution to astronomy for six year has been its "unparalleled optical resolution from Earth orbit" (according to all official NASA press releases) -- why wouldn't you target Hale-Bopp with Hubble's (now) superb and proven optics? With scientific questions still outstanding, regarding the "size and nature" of a comet's nucleus; the "size and distribution of the eruptions of material occurring on its surface"; and the major, fundamental questions now being posed by Van Flandern's critical prediction of the never-before-seen existence of actual "cometary satellites"--

A simple set of superb, high-resolution Hale-Bopp images from Hubble confirming or disconfirming any of these key phenomena -- would have been a profound legacy for 20th Century Science.

Instead, we have "excuses" ...