A Brief History of High-Energy Astronomy: 2000 - 2004

In Reverse Chronological Order

Dec 27 2004 Detection of a giant hard X-ray/gamma-ray flare from the Soft Gamma Repeater SGR 1806-20 by NASA's Swift and RHESSI X-ray and gamma-ray observatories. This gamma-ray event lasted about two tenths of a second and had an (isotropic) energy of more than 1046 erg, one hundred times more powerful than previously observed outbursts of this object. SGR 1806-20 is believed to be a magnetar, or a highly magnetized neutron star, with a magnetic field strength of ~ 1015 G. This giant flare was so powerful that it produced a significant disturbance in the Earth's ionosphere. The flare is believed to be due to a magnetic reconnection event on the surface of the magnetar, and the subsequent evolution of the ejected material was followed by several radio telescopes, including the Very Large Array. Several papers in Issue 7037, Volume 434 of Nature (published in April 2005) have analyzed this event, e.g., Hurley et al. (2005, Nature, 434, 1098).
Dec 25 2004 Successful release of the Huygens probe from the Cassini spacecraft orbiting Saturn. The Huygens probe made a successful parachute descent onto the surface of Titan 20 days later, on Jan 14 2005, telemetering back to Earth unique imagery and data about the atmosphere and `landforms' of this fascinating satellite.
Dec 17 2004 Voyager 1, the farthest flung human artefact in space, crosses the termination shock, the first of 3 boundaries separating the heliosphere from the general interstellar medium (ISM), at a distance of 94 Astronomical units (14 billion km) from the Sun. Voyager 1 is now inside the heliosheath moving out towards the heliopause, the boundary between solar wind plasma and ISM plasma, and still sending back data about this hitherto unexplored environment.
Nov 20 2004 at 12:16 pm EST Successful launch on a Delta rocket from Cape Canaveral AFS of the Swift Gamma-Ray Burst Explorer, a NASA medium-class explorer (MIDEX) mission with participation from the Italian Space Agency (ASI) and the UK Particle Physics and Astronomy Research Council (PPARC). Swift is a three-telescope space observatory for studying gamma-ray bursts which has the unique ability to repoint its UV/optical, and X-ray telescopes to the position in the sky of a gamma-ray burst within about one minute of its occurrence. It is expected that Swift will detect more than 100 gamma-ray bursts and their afterglows per year. Swift will also survey the sky for black holes and other sources of cosmic gamma-rays: it is predicted that it will find 400 or so new supermassive black holes. (Still operational).
Aug 18-19 2004 First astronomical observation by the Stratospheric Observatory for Infrared Astronomy (SOFIA), a joint project of NASA and DLR (the German Aerospace Center). This ground-based `first light' observation was of the star Polaris: normal operations for this Boeing 747SP-based telescope will be conducted at altitudes above 40,000 feet where the sky is much more transparent to IR radiation than at lower altitudes.
Aug 3 2004 Successful launch of NASA's MESSENGER (Mercury Surface, Space Environment, Geochemistry, and Ranging) mission to Mercury. In order to become the first spacecraft ever to orbit Mercury, MESSENGER must follow a tortuous path through the inner solar system, including one flyby of Earth, two flybys of Venus, and three flybys of Mercury, prior to its insertion into orbit around Mercury on 2011 March 18. This mission will return the first new data from Mercury in more than 30 years (since the 3 Mercury flybys by Mariner 10 in 1974 and 1975, in fact).
Jul 1 2004 Successful insertion into orbit around Saturn of the joint NASA-ESA-ASI mission Cassini-Huygens, marking the beginning of its primary 4-years mission of exploration of the planet Saturn, its moons (particularly Titan), and its rings. (Still operational).
Apr 20 2004 at 12:57 pm EDT Successful launch on a Delta rocket from Vandenberg AFB of NASA's Relativity Mission, Gravity Probe-B (GP-B), an experiment comprising four incredibly precise gyroscopes which will test two predictions of Einstein's Theory of General Relativity, namely the existence and the magnitude of the gravitomagnetic (`frame-dragging') and geodetic forces that are predicted by this theory.
Jan 20 2004 at 07:44 UT (peak) A large (Geosynchronous Operational Environmental Satellites (GOES) x-ray class M6.1) flare occurs on the Sun. This flare was strong enough to produce a sudden ionospheric disturbance in the earth's atmosphere. The Chandra X-Ray Observatory (CXO) was fortuitously observing Saturn in soft X-rays on this day, and detected a simultaneous factor of 7 increase in the emission from the planet's disk (after correcting for the 134 minutes light-travel time difference), which Bhardwaj et al. (2005, ApJ, 624, L121) argue is due to solar flare X-ray emission scattering from and causing fluorescence in Saturn's upper atmosphere.
Nov 4 2003 at 19:50 UT (peak) Detection of the most powerful solar X-ray flare ever recorded, by the GOES and solar X-ray satellites. This flare, which saturated the Geosynchronous Operational Environmental Satellites (GOES) X-ray detectors, was estimated to be an X28 flare (which means an X-ray flux in the 1 - 8 Angstrom band (1.5 - 12 keV energy band) of 2.8 erg cm-2 s-1 at the distance of the Earth from the Sun, equivalent to an X-ray luminosity in this band of 8 x 1027 erg s-1), and was associated with a high-velocity (2300 km s-1, almost 1% of the speed of light) coronal mass ejection (CME).
Sep 21 2003 Successful de-orbiting of the Galileo spacecraft into the planet Jupiter following a highly successful mission. This maneuver was designed to eliminate any chance that Galileo would, if left in orbit in the Jovian system, impact the Jovian moon Europa: Europa has a subsurface ocean (discovered by Galileo instruments) which is considered a possible site for extraterrestrial life, and hence a site to be protected.
Aug 25 2003 at 1:36 am EDT Successful launch of NASA's Space Infrared Telescope Facility (SIRTF) on a Delta 7920H rocket. SIRTF, renamed by NASA to the Spitzer Space Telescope on 2003 December 18, is the fourth (and last) of NASA's `Great Observatories', and is capable of imaging and spectroscopy in the infrared band from 3.6 to 160 microns. (Still operational).
The other Great Observatories are (or were) the Hubble Space Telescope or HST (ultraviolet, optical and near-infrared bands), the Chandra X-Ray Observatory or CXO (soft X-ray band), and the Compton Gamma-Ray Observatory or CGRO (hard X-ray and gamma-ray bands). [CGRO was deorbited in June 2000, notice].
Apr 29 2003 at 22:06 UT The reentry and destruction of the Italian-Dutch BeppoSAX satellite over the Pacific Ocean at an approximate position of 130 degrees West, 3 degrees North.
Apr 28 2003 The launch on a Pegasus rocket of NASA's Galaxy Evolution Explorer (GALEX) mission, an orbiting space telescope that is observing galaxies in ultraviolet (UV) light so as to study their evolution over the last 10 billion years of cosmic history. GALEX will conduct several sky surveys, including an extragalactic UV all-sky survey.(Still operational).
Mar 29 2003 at 11:37 UT The discovery with the HETE-2 satellite of an extremely bright gamma-ray burst (GRB 030329) coincident with a bright supernova or hypernova, SN2003dh, reported by Ricker et al. (2003, IAUC No. 8101). The GRB fluence in the band from 30 - 400 keV was about 1.2 x 10-4 erg cm-2, integrated over the approximately 50 second burst duration. This was the brightest GRB detected by HETE to this date and ranks among the brightest 0.2% of all GRBs previously detected (in fact, the prompt X-rays and/or gamma-rays from this burst were intense enough to cause a Sudden Ionospheric Disturbance in the Earth's ionosphere, according to Price et al. 2003, IBVS No. 5415). Studies of the afterglow of this GRB soon found spectroscopic features characteristic of a core-collapse supernova (e.g., Garnavich et al. 2003, IAUC No. 8108). The properties of this event appear to confirm that `typical, long-duration, energetic GRBs result from the deaths of massive stars', i.e., the collapsar model: see, for example, the papers by Uemura et al., Price et al. and Hjorth et al. (2003, Nature, 423, 843 et seq.) and by Stanek et al. (2003, ApJ, 591, L17) for more details.
Feb 1 2003 at ~14:00 UT Destruction of the space shuttle Columbia and loss of all seven astronauts, as it was re-entering the Earth's atmosphere.
Jan 23 2003 Last, very weak signal received from Pioneer 10. It is believed that the radioisotope generator on-board this spacecraft decayed to a level insufficient to send a transmission to the Earth shortly after this, as the next contact attempt (on Feb 7, 2003) was unsuccessful.
Jan 2003 Announcement by NASA of its Beyond Einstein roadmap for the Structure and Evolution of the Universe theme. The Beyond Einstein program has three linked elements which advance science and technology towards two visions: to detect directly gravitational wave signals from the earliest possible moments of the Big Bang, and to image the event horizon of a black hole. The central element is a pair of Einstein Great Observatories, Constellation-X and LISA. These powerful facilities will blaze new paths to the questions about black holes, the Big Bang, and dark energy. They will also address other central goals of contemporary astrophysics. The second element is a series of competitively selected Einstein probes, each focused on one of the science questions. The third element is a program of technology development, theoretical studies, and education, to support the Probes and the vision missions: the Big Bang Observer and the Black Hole Imager.
Jan 13 2003 at 00:45 UT Successful launch of the Cosmic Hot Interstellar Plasma Spectrometer (CHIPS) on a Delta II rocket launched from Vandenberg Air Force Base which also carried the ICESAT satellite. CHIPS is a NASA University-Class Explorer (UNEX) mission that will carry out all-sky spectroscopy of the diffuse background at wavelengths from 90 to 260 Å (energies from 0.048 to 0.14 keV), with a peak resolution of lambda/150 (about 0.5 eV). CHIPS data will be used to study the electron temperature, ionization conditions, and cooling mechanisms of the million-degree plasma that is believed to fill the `local interstellar bubble'. The majority of the luminosity from this diffuse million-degree plasma is expected to emerge in the poorly-explored CHIPS band, making CHIPS data of relevance in a wide variety of Galactic and extragalactic astrophysical environments. (still operational)
Dec 6 2002 Claimed detection of linear polarization in a cosmic gamma-ray source, viz. a gamma-ray burst, by the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI). This measurement was obtained using Compton scattering between the germanium detectors in RHESSI's rotating array, and, if valid, would strongly constrain emission models for gamma-ray bursts. For more details, see the original paper by Coburn and Boggs (2003, Nature, 423, 415) in which a detection is claimed, and a rebuttal paper by Rutledge and Fox (2004, MNRAS, 350, 1288) in which a detection is discounted.
Oct 17 2002 at 4:41 UT Successful launch of the International Gamma-Ray Astrophysics Laboratory (INTEGRAL), an ESA/NASA/Russian Space Agency gamma-ray astronomy observatory that can perform both spectroscopy and imaging on celestial gamma-ray sources in the energy range from 15 keV to 10 MeV, as well as concurrently monitor them in the X-ray and optical domains. (Still operational)
Oct 8 2002 Riccardo Giacconi is (co-)awarded the 2002 Nobel Prize in Physics "for pioneering contributions to astrophysics, which have led to the discovery of cosmic X-ray sources". Dr. Giacconi discussed these contributions, including the discovery of the first cosmic X-ray source in 1962, as well as his major role in the development of grazing-incidence optics for X-ray imaging, in his Nobel Lecture, which was subsequently published in Rev. Modern Physics, 75, 995 (2003). (Raymond Davis, Jr. and Masatoshi Koshiba shared the second half of the Nobel Prize "for pioneering contributions to astrophysics, in particular for the detection of cosmic neutrinos").
Sep 10 2002 The definite detection of the planet Saturn as an X-ray source, by the XMM-Newton Observatory. Ness et al. (2004, A&A, 414, L49) found Saturn to have an X-ray flux of 1.6 x 10^-14 erg/cm^2/s in the 0.1 - 2 keV energy band. A later observation (Apr 14 2003) made by the same research team using the Chandra X-Ray Observatory found a somewhat lower X-ray flux of 0.7 x 10^-14 erg/cm^2/s (equivalent to an X-ray luminosity ~ 0.1 GigaWatts). Chandra's high spatial resolution showed that this emission was concentrated in the equatorial region of Saturn's disk, in contrast to the Jovian X-ray emission which is predominantly in the polar regions.
Apr 30 2002 End of mission operations of the Italian Space Agency X-ray observatory BeppoSAX, six years to the day after its launch, due to the poor and degrading spacecraft condition and its rapid orbital decay. BeppoSAX made a number of important discoveries during its mission: its identification of gamma-ray bursts as distant extragalactic events rather than local galactic ones was perhaps its most significant finding.
Feb 27 2002 Re-entry of the Spanish satellite Minisat 1. This satellite carried the Low-Energy Gamma-Ray Imager (LEGRI) instrument, a coded-mask hard X-ray/gamma-ray telescope.
Feb 5 2002 Launch of the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI). This NASA Small Explorer (SMEX) spacecraft had. as its primary mission, the goal of exploring "the basic physics of particle acceleration and energy release in solar flares". It performs simultaneous, high-resolution imaging and spectroscopy of solar flares from 3 keV X-rays to 17 MeV gamma rays, with high time-resolution. It also has a secondary capability to observe cosmic high-energy phenomena such as gamma-ray bursts. (Still operational).
Jan 31 2002 at 04:15 UT Re-entry of the EUVE satellite into the Earth's atmosphere, after more than 9 years in orbit where it had been the first major satellite dedicated to making observations in the extreme-ultraviolet (70-760 Angstroms in wavelength, equivalent to 0.016-0.163 keV in photon energy). According to calculations made by the United States Space Command Space Control Center, EUVE re-entered the atmosphere over central Egypt. EUVE revolutionized the field of extreme-ultraviolet astronomy: despite some pessimistic predictions that it would detect only a small number of sources due to the high opacity of the interstellar medium at these wavelengths, it actually detected a couple of thousand objects, including more than a dozen extragalactic objects.
Jul 4 2001 First detection of X-ray emission from the third (in size) terrestrial planet in the Solar System, namely Mars, by the Chandra Observatory: see Dennerl et al., A&A, 394, 1119 (2002) for further details. About 300 X-ray photons were detected during a 9-hour observation of Mars. The X-ray emission is believed to be due to fluorescent scattering of solar X-rays by oxygen atoms in the planet's atmosphere, which is mostly carbon dioxide.
Jun 30 2001 at 19:47 UT Launch on a Delta II-7425-10 rocket of the Wilkinson Microwave Anisotropy Probe (WMAP), a NASA Explorer mission to make a full sky map of the faint anisotropy or variations in the temperature of the cosmic microwave background radiation. The patterns in this radiation across the sky encode a wealth of details about the history, shape, content, and ultimate fate of the Universe. WMAP was the first mission to use an L2 orbit as its permanent observing station. L2 is a semi-stable region of gravity that is about 4 times further away from the Earth than the Moon, following the Earth around the Sun.
Mar 23 2001 at 05:00 UT Re-entry over the southern Pacific Ocean of the Mir Space Station after 86,000 total orbits since its launch in February 1986.
Mar 2 2001 at 05:21 UT Re-entry of the ASCA satellite into the Earth's atmosphere, after more than 8 years in orbit where it was one of the major X-ray observatories of the last decade. The orbital re-entry occurred over the western Pacific Ocean, at 8.2 degrees South latitude, and 163.2 degrees East longitude.
Jan 31 2001 End of mission operations of NASA's Extreme UltraViolet Explorer (EUVE), the first mission dedicated to observing in the relatively unexplored extreme-ultraviolet region of the spectrum.
Jan 10 & 13 2001 First detection of X-ray emission from another terrestrial planet in the Solar System, namely Venus, by the Chandra Observatory: see Dennerl et al., A&A, 386, 319 2002 for further details. The emission was from the sunlit portion of the Venusian disk, and its spectrum is consistent with fluorescent scattering of solar X-rays in the planet's atmosphere.
Nov 16 2000 End of operations of the Unconventional Stellar Aspect (USA) Experiment, one of nine experiments on board the Advanced Research and Global Observation Satellite (ARGOS), which was designed to do X-ray timing and time-resolved spectroscopy of relatively bright X-ray sources, such as X-ray binaries.
Oct 9 2000 at 5:38 UT Launch of NASA's High-Energy Transient Experiment 2 (HETE-2) to carry out a multiwavelength study of cosmic gamma-ray bursts (GRBs) with UV, X-ray, and gamma-ray instruments. HETE-2 is an international collaboration led by the Center for Space Research at MIT. Unique features of the mission are the ability to localize GRBs to an accuracy of several arcseconds, in near-real time, aboard the spacecraft, and to relay the coordinates to the ground for distribution to interested observers within seconds of burst detection. This will allow the latter to make detailed observations at optical and other wavebands of the initial phases of GRBs. HETE-2 was declared fully operational on Feb 16 2001.
Sep 14 2000 Publication of an article discussing the detection of interference fringes in the X-ray range using a grazing-incidence interferometer. This laboratory experiment achieved an angular resolution of 0.1 arcseconds which was superior to any existing X-ray telescope and the authors argued that a scaled-up version in space installed in 2 formation-flying spacecraft could reach sub-microarcsecond angular resolution. See Cash et al. (2000, Nature, 407, 160) for more details.
Jun 4 2000 Planned de-orbiting of the Compton Gamma Ray Observatory; this was necessary due to the failure of one of Compton's three gyroscopes. Since at least two gyroscopes are required for the spacecraft to have attitude control, the loss of a second gyroscope would have meant that a controlled re-entry would have been impossible. Compton was therefore deliberately de-orbited by NASA, destroying the spacecraft, but ensuring that its fragments harmlessly splashed into the Pacific Ocean. Re-entry was at approximately 2:10 am Eastern Daylight Time on June 4th, with an approximate impact site 2400 miles southeast of Hawaii in the Pacific.
Feb 10 2000 Failed launch of the 5th Japanese X-Ray Astronomy Mission (Astro-E), which had the goals of observing astronomical objects at cosmological distances in X-ray wavelengths, and of performing high spectral resolution and wide-band X-ray spectroscopy of cosmic high-temperature plasmas. Astro-E would have covered the energy range from 0.4 to 700 keV with three instruments, an X-ray micro-calorimeter (the X-Ray Spectrometer or XRS), a set of four X-ray CCD cameras (the X-ray Imaging Spectrometer or XIS), and the Hard X-ray Detector or HXD. Unfortunately, due to a first stage rocket malfunction, it failed to achieve orbit and was lost.

Events in 1995-1999


We would like to thank the following individuals for their contributions to this page: Jesse S. Allen, and Ian M. George along with JPL's Space Calendar and the Working Group for the History of Astronomy's Astronomiae Historia (History of Astronomy) information pages.

All dates/times are east-coast time for the U.S.A., unless otherwise stated. Please send information concerning dates/deadlines not currently included and/or corrections to:

Steve.Drake @ gsfc.nasa.gov

Web page author: Stephen A. Drake (based on an original by Jesse S. Allen)

Web page maintainer: Stephen A. Drake

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