February 2012
Space
  • NuSTAR Launch Vehicle
  • 1 February 2012

  • By Various

  • NuSTAR will launch into a low-Earth, near-equatorial orbit on a Pegasus XL rocket from the Kwajalein Atoll. The Pegasus launch vehicle, built by Orbital Sciences Corporation, relies on a unique air-launch system with the rocket released at approximately 40,000 feet from the "Stargazer" L-1011 aircraft. The rocket then free-falls in a horizontal position for five seconds before igniting its three-stage rocket motor. The Pegasus is one of the most flexible and reliable small launch vehicles, with 40 launches as of October 2008 and 26 consecutive successful launches since 1997.

    The NuSTAR launch will be the fourth Pegasus launch conducted from the Kwajalein Atoll (8deg43min N, 167deg44min E). Kwajalein is the world's largest coral atoll, with a total landmass of 2.4 square miles split between 97 islets surrounding a 324 square mile lagoon. Kwajalein sits at the middle of the Ralik (sunset) Chain of the Marshall Islands, which lie midway between Hawaii and Australia, approximately 2000 nautical miles from each. As of 1986, the Republic of the Marshall Islands is independent, but maintains strong ties with the United States and hosts the Ronald Reagan Ballistic Missile Defense Test Site on Kwajalein Atoll.

    The Pegasus launch from Kwajalein will position NuSTAR in a low-Earth equatorial orbit at an altitude of approximately 550 km and an inclination of 6 degrees. The equatorial orbit is particularly important for NuSTAR as it will minimize exposure to the South Atlantic Anomaly (SAA), the region centered above the southern Atlantic Ocean where the Earth's inner Van Allen belt makes its closest approach to the Earth's surface. Satellites at altitudes of a few hundred kilometers and in orbits inclined relative to the equator will experience intense particle radiation during passages through the SAA. This is particularly problematic for high energy X-ray telescopes due to the high level of radioactive background thus produced in the detectors. This background will produce signals that mimic the cosmic X-ray emission that NuSTAR aims to detect.

    The NuSTAR launch is currently scheduled for March 2012.

    About NuSTAR:

    The Nuclear Spectroscopic Telescope Array.

    The NuSTAR mission will deploy the first focusing telescopes to image the sky in the high energy X-ray (6 - 79 keV) region of the electromagnetic spectrum. Our view of the universe in this spectral window has been limited because previous orbiting telescopes have not employed true focusing optics, but rather have used coded apertures that have intrinsically high backgrounds and limited sensitivity.

    During a two-year primary mission phase, NuSTAR will map selected regions of the sky in order to:

    1. take a census of collapsed stars and black holes of different sizes by surveying regions surrounding the center of own Milky Way Galaxy and performing deep observations of the extragalactic sky;
    2. map recently-synthesized material in young supernova remnants to understand how stars explode and how elements are created; and
    3. understand what powers relativistic jets of particles from the most extreme active galaxies hosting supermassive black holes.

    In addition to its core science program, NuSTAR will offer opportunities for a broad range of science investigations, ranging from probing cosmic ray origins to studying the extreme physics around collapsed stars to mapping microflares on the surface of the Sun. NuSTAR will also respond to targets of opportunity including supernovae and gamma-ray bursts.

    The NuSTAR instrument consists of two co-aligned grazing incidence telescopes with specially coated optics and newly developed detectors that extend sensitivity to higher energies as compared to previous missions such as Chandra and XMM. After launching into orbit on a small rocket, the NuSTAR telescope extends to achieve a 10-meter focal length. The observatory will provide a combination of sensitivity, spatial, and spectral resolution factors of 10 to 100 improved over previous missions that have operated at these X-ray energies.

    A NASA Small Explorer (SMEX) mission, NuSTAR is currently in Phase C/D and is scheduled to launch into low-Earth equatorial orbit in March 2012