DISCOVERY

The discovery is similar to finding a gushing oil well just off shore: an object in the space near Earth whose
contents can be used directly as rocket propellant and whose orbit is relatively accessible to Earth. Marsden (1992)
reported this 14 August 1992 that theNEO 1979 VA displayed a trail in 1949, which is the telltale feature of a
comet..

This object is part of a swarm of NEOs in the space near Earth. Figure 1 shows the Swarm orbits and the 208
known NEOs as of July 22, 1992, courtesy of Sykes (1992). The dots trace the orbits and the heavy dots indicate the
position of the NEO at that time. The density of dots per unit area displays the probability of finding an NEO in that
area. There are many to choose from. See Arghavani et. al., (1985 and 1984);A'Hearn et. al. (1992); Fanale et. al.
(1991),Friedlander et. al, (1990), Lebovsky; McFadden ; Ostro (1992); Russell (1987 & 1990); Russell et. al. 1984;
Shoemaker et. al. 1978; Sykes; and Zuppero et. al. (1991, 1992).

Wetherill(1991) predicted that the final meta-stable orbits of comets is a distribution essentially indistinguishable
from the observed distribution of NEOs. He suggested that those ~0.01% of the comets that don't get sucked into
Jupiter or Saturn or become ejected from the solar system have orbits that migrate into orbits that cross or come
close to Earth and have semi-major axes that lie somewhere in the asteroid belt.

Dr. Edward Bowell of the Lowell Observatory searched the records of Mt. Palomar to seek previous observations
of some unusual NEOs and came across the sighting of the NEO "1979 VA" in a 1949 plate, shown in Figure 2. The
observation looked like a comet trail.to his colleague, Dr. Brian Marsden, at the Smithsonian, who observed that this
was indeed the comet formerly named Object 4015, Comet Wilson Harrington. They reported it on 14 August 1992.
About 5 km across, it may have about 20 Billion (20E10) metric tons of water ice. This is a massive, new space
transportation and mineral resource in the spacenear Earth. It's gravity is very low and about 1/10,000 that of Earth,
which is crucial for it to be useful to us.

Dr. Eugene Shoemaker, of the USGS, Flagstaff, faxed a copy of that plate to the Idaho National Engineering
Laboratory on 21 August 1992. Shoemaker had been working with Zuppero (1991 & 1992) on the feasibility of

FIGURE 1. The objects ( larger dots) and orbits (dotted
lines) of the 208 known NEO's as of 22 July 1992.

FIGURE 2. A comet plume revealing the tell-tale sign of
water in what was thought to be just a rock named 1979^{first sighting in 1949, by Wilson & Harrington}
VA.