High Energy Transient Explorer 1 (HETE-1) was a

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

astronomical satellite with international participation (mainly

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

and

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

History

The concept of a satellite capable of multi-wavelength observations of

gamma-ray burst In gamma-ray astronomy, gamma-ray bursts (GRBs) are extremely energetic events occurring in distant Galaxy, galaxies which represent the brightest and most powerful class of explosion in the universe. These extreme Electromagnetic radiation, ele ...

s (GRB) was discussed at the

Santa Cruz, California Santa Cruz (Spanish language, Spanish for "Holy Cross") is the largest city and the county seat of Santa Cruz County, California, Santa Cruz County, in Northern California. As of the 2020 United States census, 2020 census, the city population ...

meeting on GRBs in 1981. In 1986, the first realistic implementation of the HETE concept by a

Massachusetts Institute of Technology The Massachusetts Institute of Technology (MIT) is a Private university, private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of moder ...

MIT-led International Team was proposed. This concept, which was adopted, emphasized accurate locations and multi-wavelength coverage as the primary scientific goals for a sharply-focused small satellite mission which would ultimately solve the gamma-ray burst mystery. In 1989, NASA approved funding for a low-cost "University Class" explorer satellite to search for GRBs. In 1992, the HETE-1 program was funded, and the design and construction of HETE-1 began. The original spacecraft contractor for HETE-1 was AeroAstro, Inc., of

Herndon, Virginia Herndon is a town in Fairfax County, Virginia, United States. Located in Northern Virginia, it is part of the Washington, D.C., metropolitan area, Washington, D.C. metropolitan area. In 2020, the population at the census was 24,655, which makes i ...

. AeroAstro was responsible for the spacecraft bus, including power, communications, attitude control, and computers. The instrument complement for HETE-1 consisted of four wide-field gamma-ray detectors, supplied by the CESR of

Toulouse Toulouse (, ; ; ) is a city in southern France, the Prefectures in France, prefecture of the Haute-Garonne department and of the Occitania (administrative region), Occitania region. The city is on the banks of the Garonne, River Garonne, from ...

. A wide-field coded-aperture X-ray imager, supplied by a collaboration of

Los Alamos National Laboratory Los Alamos National Laboratory (often shortened as Los Alamos and LANL) is one of the sixteen research and development Laboratory, laboratories of the United States Department of Energy National Laboratories, United States Department of Energy ...

(LANL) and the Institute of Chemistry and Physics (

RIKEN is a national scientific research institute in Japan. Founded in 1917, it now has about 3,000 scientists on seven campuses across Japan, including the main site at Wakō, Saitama, Wakō, Saitama Prefecture, on the outskirts of Tokyo. Riken is a ...

) of

Tokyo Tokyo, officially the Tokyo Metropolis, is the capital of Japan, capital and List of cities in Japan, most populous city in Japan. With a population of over 14 million in the city proper in 2023, it is List of largest cities, one of the most ...

. Four wide-field near-UV CCD cameras, supplied by the

Center for Space Research The MIT School of Science is one of the five schools of the Massachusetts Institute of Technology, located in Cambridge, Massachusetts, United States. The School, which consolidated under the leadership of Karl Taylor Compton in 1932, is composed ...

at the Massachusetts Institute of Technology. Due to the tragic fate of HETE-1 and the continuing timeliness of GRB science, NASA agreed to a reflight of the HETE-1 satellite, using flight spare hardware from the first satellite. In July 1997, funding for a second HETE satellite was granted, with a target launch date early 2000.

Mission

The prime objective of HETE-1 was to carry out the first multi-wavelength study of GRBs with

ultraviolet Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of ...

(UV),

X-ray An X-ray (also known in many languages as Röntgen radiation) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays. Roughly, X-rays have a wavelength ran ...

, and

gamma-ray A gamma ray, also known as gamma radiation (symbol ), is a penetrating form of electromagnetic radiation arising from high energy interactions like the radioactive decay of atomic nuclei or astronomical events like solar flares. It consists ...

instruments mounted on a single, compact spacecraft. A unique feature of the HETE-1 mission was its capability to localize GRBs with ~10

arcseconds A minute of arc, arcminute (abbreviated as arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of a degree. Since one degree is of a turn, or complete rotation, one arcminute is of a tu ...

accuracy in near real time aboard the spacecraft, and to transmit these positions directly to a network of receivers at existing ground-based observatories enabling rapid, sensitive follow-up studies in the

radio Radio is the technology of communicating using radio waves. Radio waves are electromagnetic waves of frequency between 3 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connec ...

infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...

(IR), and

visible light Light, visible light, or visible radiation is electromagnetic radiation that can be perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400–700 nanometres (nm ...

bands.

Spacecraft

The satellite bus for the HETE-1 satellite was designed and built by AeroAstro, Inc. (USA) of

. The HETE-1 spacecraft was Sun-pointing with four

solar panels A solar panel is a device that converts sunlight into electricity by using photovoltaic (PV) cells. PV cells are made of materials that produce excited electrons when exposed to light. These electrons flow through a circuit and produce direct ...

connected to the bottom of the spacecraft bus. Spacecraft attitude was to be controlled by magnetic torque coils and a momentum wheel.

Experiments

Omnidirectional Gamma-Ray Spectrometer

The Omnidirectional Gamma-Ray Spectrometer was designed to operate from 6

keV In physics, an electronvolt (symbol eV), also written electron-volt and electron volt, is the measure of an amount of kinetic energy gained by a single electron accelerating through an electric potential difference of one volt in vacuum. When us ...

to greater than 1 MeV. The instrument consisted of four wide-field gamma-ray detectors with a total effective area of . The HETE satellite remained within the launch vehicle due to battery failure. The experiment was unable to operate.

Ultraviolet Transient Camera Array

The Ultraviolet Transient Camera Array was designed to provide accurate directional information on transient events, and to assist with spacecraft attitude determination. The instrument consisted of four ultraviolet

Charge-coupled device A charge-coupled device (CCD) is an integrated circuit containing an array of linked, or coupled, capacitors. Under the control of an external circuit, each capacitor can transfer its electric charge to a neighboring capacitor. CCD sensors are a ...

(CCD) cameras operating in the 5 to 7 eV range.

Wide Field X-ray Monitor

The Widefield X-ray Monitor was designed to perform X-ray studies of gamma-ray bursts. The instrument consisted of coded aperture cameras, sensitive in the 2-25 keV energy range, and with location accuracy to ~ 10 arcminutes or better.

Launch

The HETE-1 satellite was launched with the

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satellite SAC-B. HETE-1 was lost during the launch on 4 November 1996, at 17:08:56

UTC Coordinated Universal Time (UTC) is the primary time standard globally used to regulate clocks and time. It establishes a reference for the current time, forming the basis for civil time and time zones. UTC facilitates international communica ...

, from

Wallops Flight Facility Wallops Flight Facility (WFF) is a rocket launch site on Wallops Island on the Eastern Shore of Virginia, United States, just east of the Delmarva Peninsula and approximately north-northeast of Norfolk, VA, Norfolk. The facility is operated ...

(WFF), launch area-3. The Pegasus XL

launch vehicle A launch vehicle is typically a rocket-powered vehicle designed to carry a payload (a crewed spacecraft or satellites) from Earth's surface or lower atmosphere to outer space. The most common form is the ballistic missile-shaped multistage ...

achieved a good orbit, but explosive bolts releasing HETE-1 from another satellite, SAC-B, and from its Dual Payload Attach Fitting (DPAF) envelope failed to charge, dooming both satellites. A battery on the third stage of the launch vehicle and responsible for these bolts cracked during the ascent. Due to its inability to deploy the solar panels, HETE lost power several days after launch.

Atmospheric entry

HETE-1 re-entered on 7 April 2002.

References

{{Orbital launches in 1996 Gamma-ray telescopes X-ray telescopes Space telescopes Satellites orbiting Earth Spacecraft launched in 1996 Spacecraft launched in 2000 Spacecraft launched by Pegasus rockets Explorers Program