Kronos MIDEX Mission




Welcome to the webpage for the Kronos MIDEX mission.

What is Kronos?

Kronos is a multiwavelength observatory designed to map the accretion disks and environments of supermassive black holes in active galactic nuclei and stellar-sized black holes, neutron stars, and white dwarfs in Galactic binary systems. Kronos makes use of the natural intrinsic variability of accretion-driven sources through sophisticated timing-based methodologies that allow us to map these sources at effectively microarcsecond angular resolution: this is 10,000 times smaller than Hubble Space Telescope images, and far beyond the capabilities of any current or near-horizon technology. The Kronos Observatory, designed for operation in a high-Earth orbit environment to maximize on-source observing time, is comprised of sensitive X-ray (0.1-10 keV), far ultraviolet (100-170 nm), and near-ultraviolet/visible (270-540 nm) spectrophotometers.

Kronos is designed to answer key questions about how sources powered by gravitational accretion work, thus providing a key element in understanding how galaxies form and evolve:

  1. What is the structure of accretion flows onto black holes and other compact objects?
  2. What is the physical origin of the radiation from black-hole systems?
  3. What are the structure and kinematics of the broad-line emitting region in active galactic nuclei?

Kronos is being proposed to the NASA Office of Space Science (OSS) as a Medium Explorer (MIDEX) mission under the Structure and Evolution of the Universe theme.

Brief technical description of the Kronos science program.
Technical paper on reverberation mapping simulations for Kronos, submitted to Publications of the Astronomical Society of the Pacific :

Kronos: It’s About Time!

Kronos uses powerful innovative tomographic techniques to probe the inner structure of black holes in unprecedented detail. High time resolution, long-duration sequences of observations are the key element of the Kronos program. Kronos makes movies of accretion-driven sources.

An important enabling factor in the Kronos program is a long-period (13.7-day) high-Earth orbit that allows long, uninterrupted sequences of observation of variable sources.

Time coverage with the Kronos observatory.
Kronos orbit description.

Kronos Mission Overview

Kronos is being proposed for flight under the 2001 NASA Medium Explorer (MIDEX) Announcement of Opportunity. If selected, Kronos will be launched in approximately March 2007 from Cape Canaveral Air Force Station (adjoining Kennedy Space Center) on a Delta 2925-10 launch vehicle. The Kronos science program will run for 30 months, obtaining long-duration, high time-resolution, multiwavelength observations of active galactic nuclei, blazars, soft X-ray transients, and cataclysmic variables, plus observations of flare stars, pre-main-sequence stars, and other targets of opportunity.

The astronomical community will be invited to participate in the Kronos mission through Associate Investigator and Guest Observer programs.

Facts about the Kronos observatory.
Kronos launch vehicle.

The Kronos Team

The Kronos team is led by the principal investigator (PI) Professor Bradley M. Peterson of The Ohio State University and Deputy PI Dr. Ronald S. Polidan of NASA Goddard Space Flight Center. The team consists of partner institutions (see below) and a Science Team comprised of experts in all Kronos science and technical areas, including relevant areas of theoretical astrophysics.

Kronos team listing

Kronos Institutional/Industrial Partners

The Kronos team includes universities in the United States, the United Kingdom, and Italy, as well as US research institutions (public and private), and aerospace companies.


The Ohio State University through the Department of Astronomy is the prime contractor for the Kronos Mission. Science planning and data analysis software, on-orbit science calibrations, and overall mission management will be carried out at Ohio State.


NASA Goddard Space Flight Center in Greenbelt, Maryland, will design and fabricate the UV/VIS and X-ray instruments and perform spacecraft integration and testing.


Battelle Memorial Institute, headquartered in Columbus, Ohio, will provide project management, independent validation and verification, risk assessment, and control/sensor/instrumentation troubleshooting for the Kronos mission.

PennState University

Penn State University, located in University Park, Pennsylvania, will design and build the Kronos X-ray Camera and associated electronics.

Leicester University

University of Leicester in the UK will provide the detector system for the Kronos X-ray telescope.

Osservatorio di Bologna Padova University

The Osservatorio Astronomico di Bologna, in partnership with the University of Padova in Italy will design and construct the Kronos Ultraviolet/Visible Spectrometer.


Rutgers University in New Jersey will build the Kronos UV detectors.


University of St. Andrews in the United Kingdom will provide advanced tomographic imaging software for analysis of Kronos data.


Spectrum Astro, Incorporated of Phoenix, Arizona, will provide the Kronos spacecraft, model SA200-HP.

General Dynamics

General Dynamics Worldwide Telecommunication Systems will provide the Kronos mission with ground systems and operations support.

Sonoma State

Sonoma State University, Sonoma Center for Innovative Education in Science in Sonoma, California, will lead the Kronos Education/Public Outreach efforts.


Space Telescope Science Institute, located in Baltimore, Maryland, will develop the Kronos data pipeline and archiving system. The STScI Office of Public Outreach is a Kronos Education/Public Outreach partner.


Center of Science and Industry, a hands-on science museum located in Columbus and Toledo, Ohio, is a Kronos Education/Public Outreach partner.

Swales Aerospace

Swales Aerospace, located in Beltsville, Maryland,  will provide the key elements in the primary mirror system for the Kronos ultraviolet/visible telescope.



Proprietary links for Kronos team members only (password required):

Kronos Science: Link to the Kronos science team website at Ohio State University

Go to: [OSU Astronomy Department Home Page]

Launched 1998 August 28
Updated 2003 January 28