On 02 February, 1997 in the sci.astro "USENET" forum Van
Flandern put forward a prediction regarding the asteroid 433 Eros. This statement included a challenge to astronomers requesting them to give serious consideration to the underlying hypothesis should the prediction be confirmed by observation.
The Near Earth
Asteroid Rendezvous (NEAR) spacecraft is the first launch in the Discovery
Program, a NASA initiative for small planetary missions. NEAR is
managed for NASA by The
Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland.
NEAR was launched in February, 1996 atop a Delta II rocket on a mission to rendezvous
with 433 Eros, an S-type asteroid with estimated dimensions of 35x15x13 kilometers.
NEAR will be the first spacecraft to orbit an asteroid.
Two asteroids, 951 Gaspra and 243 Ida, were visited by NASA's Galileo spacecraft
in 1991 and 1993, respectively. A unique discovery was made when a tiny moon
was imaged in orbit around Ida. Unlike the Galileo encounters which were simple
flybys at high velocity lasting mere minutes, NEAR will execute a braking maneuver
placing it in orbit around Eros for a prolonged close-up inspection. The mission is expected to
culminate with NEAR landing on Eros in 2000.
Although the NEAR-Eros challenge has been repeated on numerous occasions no mainstream
supporter has been willing to accept the challenge under any terms, even though the
terms were open to discussion. This reflects the unfortunate trend in astronomical
theories to avoid setting falsification criteria because, if this were done,
many favored theories would likely fall.
The NEAR Challenge
The next opportunity to learn more about asteroids is the NEAR spacecraft's rendezvous and orbit
insertion around Eros in Jan. 1999. To illustrate the strength of the exploded
planet hypothesis (eph) at making successful predictions of an otherwise improbable
nature, I suggest the following challenge:
"If the NEAR rendezvous with Eros [in January, 1999]
shows it to be an isolated, single body, or even a simple 'binary
asteroid', but without a debris field orbiting it, I will publicly
concede before the next Division of Planetary Sciences meeting that
the hypothesis leading to that prediction has failed.
"If the NEAR rendezvous with Eros shows it to be accompanied
by a debris field (i.e., multiple orbiting moons), acceptors
of this challenge will publicly concede before the next DPS
meeting that the hypothesis that made that successful prediction
has earned a second look by planetary scientists."
Tom Van Flandern (02 Feb. 1997)
Under eph premises, Eros is virtually certain to have multiple orbiting moons.
In any other model, it would be a fluke if there were even one.
To make this specific, let us say three or more distinct satellites now in orbit
around Eros will constitute "multiple". A "debris field"
would consist of moons in all size ranges, from pebbles and dust grains up to
large moons visible to NEAR's cameras. Yet the spacecraft will have the ability
to detect only certain mass ranges, determined by the limitations of the optical
system and other instrumentation on board. I expect it to see many visible chunks
of debris in orbit, and to detect far more large-grain dust than is expected.
But one must draw the line somewhere, and the mainstream models clearly expect
I predict that three or more satellites 1-meter in size or larger constitutes
a win for eph (thereby conceding a simple binary asteroid with a single, Dactyl-like
orbiting moon to the mainstream).
Asteroidal Satellites and the "Exploded Planet Hypothesis"
In "Dark Matter Missing Planets & New Comets"
a new theory called the exploded planet hypothesis (eph)
was introduced. One of its consequences was the realization that natural
satellites of asteroids and comets are commonplace. The book was published before
the discovery of Comet Shoemaker-Levy 9 which consisted of more than 20 individual
members and before the Galileo spacecraft returned its images of asteroid Ida's
moon Dactyl, the first confirmed "minor satellite".
Mainstream astronomy has attempted to explain minor satellites saying they
form following a collision between bodies, such as two asteroids. Accordingly,
it is possible for two fragments from the ensuing debris cloud to become
coupled gravitationally in a mutual orbit. As for multiple comet nuclei we are
expected to believe that the gentle tidal forces exerted by a planet are sufficient
to break off relatively large chunks of material. Upon closer inspection these
argument are found to be wanting.
In a collision, every fragment either escapes or falls back to the impact site.
No sideways angular momentum needed for a stable orbit is produced. The mutual
distance between any two escaping fragments increases faster than the radius
of either gravitational sphere of influence, so they likewise can never become
These fatal dynamical objections must be overcome to form stable moons. One way
to do that is to have an explosion originating at the center of a planet instead
of at the surface of an asteroid. Then many fragments tend to follow nearly
parallel, only-slowly-diverging paths away from the planet. Meanwhile, the gravitational
spheres of influence of the slower, larger fragments increase rapidly in radius
because most of the planet's mass is soon beyond them. So all nearby debris
becomes trapped in orbit around those larger fragments. Natural dynamical and
collisional evolution eventually sort out this debris, concentrating much of
it toward the equatorial plane and toward the synchronous orbit (i.e., toward
So when a large fragment of the exploded planet, such as Comet SL-9, comes too
close to Jupiter, its orbiting debris cloud gets stripped off and spreads out
along the main fragment's orbit. You no longer need to invoke tidal forces no
stronger than blowing gently on a bit of cigar ash to break apart a comet nucleus
probably several kilometers in diameter.
Actually, collisions and explosions are surprisingly different dynamically. Collisions cause fragments
of both bodies to depart from near the point of impact. This is on the surface
of the larger body even if that body is destroyed by the collision. An eph-type
explosion originates at the center of the larger body. This results in three
differences relevant to satellite formation:
An impact causes the mutual separation of all fragments to increase linearly
with distance traveled away from the impact. A central explosion of a planet-sized
body allows many fragments originating far from the center to travel along
nearly parallel trajectories with similar speeds that diverge much more
In an impact, small fragments tend to leave first and travel fastest, with
large fragments lagging behind. Both mutual separation and the radius of
the gravitational sphere of influence of each increase linearly with distance
traveled away from the impact site. By contrast, in a planetary explosion,
small late-leaving fragments are being continually propelled past large
early-leaving fragments, rapidly decreasing the exploded planet's mass interior
to the large fragments. This accelerates the speed of increase of their
sphere of influence above linear with distance traveled, and allows them
to capture nearby debris.
Impacts are almost exclusively destructive. A
planetary explosion propels considerable trailing material into the larger
fragments that left first, causing them to accrete some additional mass,
and enlarge their spheres of influence faster, on the way out.
Gravitational captures from a collision event are nearly impossible. And two
adjacent fragments are outside one another's sphere of influence (which is generally
smaller than a fragment's own radius) while still in the parent body. When ejected
by an impact, the spheres of influence grow linearly with distance from the
center of the parent body. But the actual separation grows linearly with distance
from the impact site near the surface of the parent body. Since the latter is
always greater than or equal to the former, no two co-moving fragments can ever
get inside each other's spheres of influence.
With the NEAR-Eros prediction I do not claim that one success "proves"
that eph is a better model. But I do claim that it has demonstrated that it
is a model worthy to be discussed comparatively by planetary scientists in the
light of all new and existing evidence. Moreover, the eph has much to recommend
it, not the least of which are:
Eph eliminates the need for an "Oort cloud".
Eph predictively explains all the principal statistical properties of new
and old comet orbits.
Eph easily explains why new and old comet physical behavior is so drastically
Eph is the only model that correctly predicts the split comet relative velocity
vs. solar distance power law.
Eph explains why many properties of meteorites are ordinarily associated
only with major planets, such as pre-impact micro-diamonds.
Eph explains the young cosmic ray exposure ages of meteorites, and why we
seldom see two-stage exposure ages.
Eph provides the needed recent source for Earth-crossing asteroids.
Eph is a natural explanation for "explosion signatures" in main
asteroid belt orbital elements.
Eph explains the distribution of black, carbonaceous material on the airless
bodies of the solar system, most notably for Icarus.
The Tale of Two Asteroids
Many asteroid moons were discovered during stellar occultation events in the
late 1970s, and binary asteroids were featured in the review volume "Asteroids"
published in 1979. When the phenomenon started to become an embarrassment for
the standard model, participation in observing efforts by professionals was
sharply curtailed by the early 1980s, and asteroid moons were barely mentioned
except in one negative chapter in "Asteroids II" a decade later.>
International Occultation Timing Association (IOTA)
provides the predictions
and coordinates observers, both professional and amateur. Their newsletter usually
reports early results even before the journals publish the final papers. Not
only were professional efforts by U.S. astronomers down, but some amateurs were
driven away by the stinging criticisms of professionals who have done no analysis
of the reports, yet claim that flying birds and such are more likely to explain
multiple occultations than objects in the asteroid's environment.
The most famous case was the first asteroid occultation where photometers were
used. Visual observer James McMahon in California observed a 21-second occultation
of a bright star by a much fainter asteroid, Herculina. He also reported some
equally distinct but shorter secondary occultations, the longest of which lasted
Lowell Observatory recorded a photoelectric record of the combined lightcurve
that likewise showed a 21-second occultation of the star by the asteroid, with
a magnitude drop of 4-5. David Dunham called Lowell and asked about secondary
occultations. The observers reported seeing none. David then questioned McMahon
closely for any possible alternate explanation of his visual sightings, telling
him that Lowell saw no secondary events in the photoelectric record. Every possibility
anyone could conceive was ruled out, especially when considering that the faint
asteroid remained visible when the bright star disappeared.
Dunham calculated that only the secondary event that had produced the 5-second
occultation for McMahon was large enough that Lowell almost certainly must have
seen it too, if it was real. So he called Lowell back and again asked them to
scan their record for secondary events. The observers assured him there were
Dunham said, "Look at the record at 91 seconds before the primary event.
Is there anything unusual there?" The Lowell observers responded rather sheepishly
with words to the effect, "Oh, that. That does look like a 5-second, full-light-drop
occultation, but the altitude then was only 2 degrees, so we ignored it!"
A visual observer saw an occultation. A major observatory hundreds of miles away
obtained a photoelectric record of the same event at the same time relative
to the main occultation. The magnitude drop was nearly five magnitudes. The
asteroid remained visible when the star disappeared -- both to the visual observer
and to the photometer. No other events were seen in the entire photoelectric
record besides the main 21-second occultation and this 5-second secondary event.
What more could you ask for by way of confirmation?
To put this bluntly, observers sometimes see what they expect to see. The story
of the Herculina satellite is another illustration of that, since a definite
occultation event was denied to exist by the professional Lowell observers until
their attention was directed to that exact place in their lightcurve. Occultations
were previously an unchallenged type of reliable observation, even when done
by amateurs. But when occultations of stars by asteroids began finding a phenomenon
that did not fit in with current thinking, the observers and the technique were
faulted. This is bias, pure and simple.
I spent the first half of my career as a part-time observational astronomer,
and have observed and timed hundreds of occultations. I feel strongly that one
is not fully competent to reduce data without the experience of collecting it
to get a feel for the weaknesses first hand. My Melpomene occultation photoelectric
lightcurve was published in Asteroids I.
The Melpomene event is another example in reverse: At USNO we had no occultation,
but a very close appulse. We recorded for 40 minutes. During all that time,
the only time the star's light dimmed significantly was for a few brief periods
close to the time of closest approach. But the dimmings were not as deep as
total occultations, and were irregular.
Any other observer was likely to have discarded that data as changes in seeing
or some such. It might have been. But I saw the statistical improbability of
that happening just when the star and asteroid were unresolvably close, but
not at other times. And I understood the dynamics of close satellites and how
the small bodies would tend to cluster into ring arcs and could produce a series
of partial occultations such as those we saw. So I reported the data instead
of tossing it.
I suggest these two anecdotes encapsulate the difference between myself and
some mainstream astronomers: I would
rather err in the direction of presenting possibly significant data and let
history judge its usefulness. Others clearly would not publish data of whatever
certainty that did not fit in with existing theory. I would
question whether such an approach is doing "serious
science", since I am convinced it retards progress.
Actually, there are more than three dozen cases of asteroid moons suggested by
earlier observations prior to Galileo's discovery of Ida's Dactyl. Of these,
perhaps a dozen are strong cases with no other viable explanation. A second
observer gave independent confirmation in two cases. See, e.g., "Minor
planets: the discovery of minor satellites", R.P. Binzel and T.C. Van Flandern,
Science 203, 903-905 (1979), for the status 18 years ago. More recent discoveries
are usually reported in IOTA's "Occultation Newsletter".
It is a shame that the individual discoverers of these asteroid moons, and D.W.
Dunham in particular who predicted the events and organized the observer efforts,
have received so little credit for their discoveries, made at a time when asteroid
moons were still thought to be a theoretical near-impossibility. Dunham reported
a satellite of 6 Hebe to the AAS in 1977, and the most common response was to
assume that Dunham was not a careful observer or a reliable astronomer. Some
reward for his role in discovering and publicizing something important and wonderful!
I'll accept a finding that Eros has no moons visible to a working, orbiting NEAR
spacecraft as a good indicator that most of the thirty or so previous observations
of secondary occultations near asteroids were spurious, and as evidence that
my best professional judgment was extremely faulty. OTOH, if NEAR shows us that
the spontaneous 1973 observations by relatively inexperienced observers of secondary
bodies close to Eros were real moons of that asteroid, then we are probably
safe to conclude that most of the later observations by more experienced observers
better prepared for the phenomenon were likewise reliable, that phenomena repeatedly
reported even by amateur astronomers should be taken seriously, and that asteroid
moons are indeed numerous and commonplace.
Tom Van Flandern (December 1997)