I skimmed through the PDF. Here are a few tidbits:
The ARTEMIS mission proposed to send the two outermost THEMIS probes, P1 and P2 (also referred to as THEMIS-B and THEMIS-C), to lunar orbits by way of two circuitous transfers that take about one and a half years each.
On February 17th, 2007, the five THEMIS probes were launched on a Delta-II 7925 rocket into a 1.3-day Earth orbit with perigee at 437 km altitude and apogee at ~87500 km altitude (Angelopoulos 2008).
The five THEMIS probes were identical at launch with 134 kg mass (including 49 kg of hydrazine monopropellant).
Each probe has four thrusters, nominally 4.4 N each
At launch, each probe had 960 m/s total ∆V capability (Harvey et al. 2008). At the start of ARTEMIS maneuvers the remaining ∆V (approximately 320 m/s for P1 and 467 m/s for P2) were available for the ARTEMIS trajectory design. Due to fuel tank depressurization (Sholl et al. 2007; Frey et al. 2008), each thruster is expected to produce between 2.4 N and 1.6 N force during the ARTEMIS mission.
Because the spacecraft is spinning the effective thrust of a sideways burn is further reduced, so a maneuver in a particular direction in the spin plane is performed by pulsing the thrusters on and off during each revolution. With a 60 deg pulse duration , the thrusters are on only one-sixth of the time (16.7% duty cycle). Because thrusters are swinging through an arc, the thrust in the desired direction is further reduced to 95.5% effective thrust; with a 40 deg duty cycle the thrusters average only one-ninth thrust, but lose only 2% in efficiency averaged through the arc of each pulse.
According to initial trajectory studies, a direct transfer from P1 Earth orbit to a 1500 km altitude by 18000 km radius polar orbit at the Moon would require ∼500 m/s of ∆V (not including margin or losses associated with long thrust arcs). This was well beyond P1’s expected ∆V capability at the end of the baseline mission.However, the remaining fuel appeared sufficient to transfer P1 from its Earth orbit to the desired eccentric polar lunar orbit by way of a lunar swing-by and low-energy transfer (Chung et al. 2005). When initiated by a lunar swing-by, this type of transfer does not require any less ∆V to leave Earth, but saves essentially all the ∆V cost of getting into a Lissajous orbit around one of the Earth-Moon Lagrange points. It does this by using solar gravity tidal perturbations to make the threebody energy change on the trajectory that would otherwise have to be done propulsively at arrival near the Moon. The fuel reserves on P2 offered similar capability, suggesting the possibility of sending two THEMIS probes to the Moon.
Table 3 ARTEMIS ∆V budget as proposed and actual (with italic values showing current estimates of ∆V to come, as of May 2011).
P1 cost est. (m/s) P1 cost act. (m/s) P2 cost est. (m/s) P2 cost act. (m/s) Deterministic DV total 200 216 343
The key thing to realize is that these probes already had a ~87500 km apogee. The ∆V calculations of the ARTEMIS mission does not include the effort of placing the probes in their initial orbits.