Point Arguello - a little history of PALC2-4 -------------------------------------------- There are two separate but physically adjacent spaceports in the Cape Canaveral vicinity: Cape Canaveral Space Force Station and the NASA John F. Kennedy Space Center. Although they are often conflated, they are owned and operated separately (by Space Force and NASA). Similarly, from 1959 to 1964 there were two separate, adjacent spaceports on the California coast north of Santa Barbara near Lompoc: Vandenberg Air Force Base and the Naval Missile Facility Point Arguello (NMFPA). The first space launch from Point Arguello was a Nike-Asp sounding rocket in Jul 1959 from Launch Complex A; the first orbital attempt was the 1960 Oct 11 launch of SAMOS 1 on an Atlas Agena A from Launch Complex 1, Pad 1. Point Arguello's Launch Complex 2, Pad 4 was not used for a launch until August 1964, by which time NMFPA had been transferred to the Air Force and become the South Base section of Vandenberg AFB - the pad was then called Vandenberg AFB PALC2-4 (Point Arguello Launch Complex 2, Pad 4). Because NMFPA was once a separate spaceport, I still track its pads separately as `South Vandenberg' with site code VS in my launch database (versus site code V for pads on the North Base). In 1966 the Vandenberg and Point Arguello orbital pads were renamed and PALC2-4 became Space Launch Complex 4-East (SLC-4E). It continued launching Atlas Agena rockets with GAMBIT spysats until 1967; from 1971 to 2005 it was the home for Titan IIID and later Titan 34D and Titan 4. After lying silent for eight years, in 2013 SLC-4E became the West Coast launch site for SpaceX's Falcon 9. So far there have been 17 Falcon 9 launches from the pad. DART ----- At 0621:02 UTC Nov 24, a Falcon 9 launched from SLC-4E at Vandenberg Space Force Base with the DART (Double Asteroid Redirection Test) spacecraft, sending it to solar orbit. Deep space launches are rare from Vandenberg; the first was the Clementine probe, launched on a Titan II from SLC-4W in 1994. Four Atlas V launches from SLC-3E in the 2009-2014 period deployed primary payloads in Earth orbit but then boosted their Centaur upper stages to solar orbit for disposal. Most recently, another Atlas V took off from SLC-3E in 2018 carrying the Mars Insight probe. The launch was the first deep space launch from Space Launch Complex 4-East. The Falcon 9 headed south from Vandenberg to a 230 x 300 km x 64.7 deg parking orbit. After a short coast, the second stage reignited over the Antarctic and boosted DART to a 263 x -135000 km x 64.7 deg escape hyperbola. DART and the second stage will depart the Earth-Sun Hill Sphere on Nov 30 at about 0700 UTC, entering a 0.938 x 1.069 AU x 3.8 deg heliocentric orbit on course for the (65803) Didymos system. (65803) Didymos is a 780-metre-diameter asteroid orbiting the Sun in a 1.01 x 1.64 AU x 3.4 deg orbit. The half-gigatonne asteroid has a moon, the 163-metre-diameter Dimorphos which has a mass of around a million tonnes and orbits Didymos at a center-to-center distance of only 1.2 km. Didymos then shuttles between the orbit of Mars and the orbit of Earth every 2.1 years. But usually when it comes close to Earth orbit, Earth itself is at some other part of that orbit. Not this time: Didymos is currently heading inward from aphelion and in Oct 2022 it will reach perihelion passing only about 11 million kilometers from Earth! OK, I know that sounds like a lot, but right now it's 113 million km away. Taking advantage of this close pass, NASA's DART mission will go round the Sun in an orbit just a little bit different from Earth's and reach Didymos just as it passes by Earth. DART will reach the Didymos system in Oct 2022 and smash into Dimorphos. The impact is expected to change the orbital period of Dimorphos around Didymos by of order ten minutes, something that can be accurately measured, allowing scientists to determine how efficiently the collision imparts momentum to the target rock. This information will be crucial in designing missions that could divert a possible future Earth-impacting asteroid. The DART mission is led by JHU's Applied Physics Laboratory (APL) and is managed by NASA MSFC and the NASA Planetary Defense Coordination Office. DART has a mass of 500 kg dry. It has two propulsion systems: a set of twelve Aerojet Rockedtyne MR-103G thrusters with a thrust of 1N each, fed by 50 kg of hydrazine; and the 7.4 kW NEXT-C ion engine with a thrust of 25 to 235 mN, fed by 60 kg of Xe and powered by two ROSA roll-out solar arrays. The main DART spacecraft, built by APL, is 1.2 x 1.3m in size and the deployed ROSA arrays span 19 metres. DART has one main instrument, the DRACO (Didymos Reconnaissance & Asteroid Camera for OpNav) imaging camera. 10 days before the Didymos encounter it will eject a 6U cubesat, LICIACube. The 14 kg LICIACube is built by Argotec for the Italian space agency ASI; it carries two cameras to image the impact.