Beyond_Earth-_A_Chronicle_of_Deep_Space_Exploration_1958-2016.pdf

Type: Document | Status: ready
← All sources

Clementine

Nation: USA (66) Objective(s): lunar orbit Spacecraft: Clementine Spacecraft Mass: 424 kg Mission Design and Management: BMDO / NASA Launch Vehicle: Titan IIG (no. 23G-11) Launch Date and Time: 25 January 1994 / 16:34 UT Launch Site: Vandenberg AFB / SLC-4W

Scientific Instruments:

  1. ultraviolet/visible camera (UV/Vis)
  2. near-infrared camera (NIR)
  3. laser image detection and ranging system (LIDAR)
  4. long-wave infrared camera (LWIR)
  5. high-resolution camera (HIRES)
  6. 2 star tracker cameras
  7. bistatic radar experiment
  8. S-band transponder Doppler gravity experiment
  9. charged particle telescope (CPT)

Results: Clementine was the first U.S. spacecraft launched to the Moon in over 20 years (since Explorer 49 in June 1973). The spacecraft, also known as the Deep Space Program Science Experiment (DSPSE), was designed and built to demonstrate a set of lightweight technologies such as small-imaging sensors and lightweight gallium arsenide solar panels for future low-cost missions flown by the Department of Defense. Specifically, Clementine was a technology proving mission for the DOD's Brilliant Pebbles program for the Strategic Defense Initiative (SDI), which required a large fleet of inexpensive spacecraft. Clementine carried 15 advanced flight-test components and 9 science instruments.

<!-- image -->

After launch, the spacecraft remained in a temporary parking orbit until 3 February 1994, at which time a solid-propellant rocket ignited to send the vehicle to the Moon. After two subsequent Earth flybys on 5 and 15 February, on 19 February Clementine successfully entered an elliptical polar orbit (430 × 2,950 kilometers) around the Moon with a period of five days. In the following two months, it transmitted about 1.6 million digital images of the lunar surface, many of them with resolutions down to 100–200 meters, in the process, providing scientists with their first look at the total lunar landscape including polar regions. After completing its mission goals over 297 orbits around lunar orbit, controllers fired Clementine's thrusters on 3 May to inject it on a rendezvous trajectory (via an Earth flyby) with the asteroid 1620 Geographos in August 1994.

However, due to a computer problem at 14:39 UT on 7 May that caused a thruster to fire and use up all propellant, the spacecraft was put in an uncontrollable tumble at about 80 rpms with no spin control. Controllers were forced to cancel the asteroid flyby and return the vehicle to the vicinity of Earth. A power supply problem further diminished the operating capacity of the vehicle. Eventually, on 20 July, lunar gravity took control of Clementine and propelled it into heliocentric orbit. The mission was terminated on 8 August when falling power supply levels no longer allowed clear telemetry exchange. Surprisingly, because the spacecraft was fortuitously in the correct attitude to power up again, ground controllers were able to briefly regain contact between 20 February and 10 May 1995. On 3 December 1996, the Department of Defense announced that Clementine data indicated that there was ice in the bottom of a permanently shadowed crater on the lunar south pole. Scientists estimated the deposit to be approximately 60,000 to 120,000 cubic meters in volume, i.e., comparable to a small lake that is four football fields in surface area and 5 meters deep. This estimate was very uncertain, however, due to the nature of the data. An accounting of Clementine's legacy should include the fact that methods developed for the project became the basis for NASA's "Faster, Better, Cheaper" initiative which ultimately paved the way for the Agency's Discovery program.

Wind

Nation: USA (67) Objective(s): Sun–Earth L1 Lagrange Point Spacecraft: Wind Spacecraft Mass: 1,250 kg Mission Design and Management: NASA / GSFC Launch Vehicle: Delta 7925-10 (no. D227) Launch Date and Time: 1 November 1994 / 09:31:00 UT Launch Site: Cape Canaveral Air Force Station / Launch Complex 17B

Scientific Instruments:

  1. radio and plasma wave experiment (WAVES)
  2. energetic particle acceleration, composition, and transport experiment (EPACT)
  3. solar wind and suprathermal ion composition experiment (SMS)
    • solar wind ion composition spectrometer (SWICS)
    • high mass resolution spectrometer (MASS)
    • suprathermal ion composition spectrometer (STICS)
  4. solar wind experiment (SWE)
  5. 2 triaxial fluxgate magnetometers (MFI magnetic field investigation)
  6. three-dimensional plasma and energetic particle investigation (3DP)
  7. transient gamma-ray spectrometer (TGRS)
  8. Konus gamma-ray burst studies experiment

Results: Wind was part of the International Solar Terrestrial Physics (ISTP) program, a joint project between (principally) the United States, Japan, and the European Space Agency (although a few other countries such as Russia, the Czech Republic, and France made significant contributions) to study the behavior of the solar-terrestrial system. Participating spacecraft included Geotail, Wind, Polar, SOHO, and Cluster. The first of two NASA-sponsored Global Geospace Science (CGS) vehicles, the Wind spacecraft carried eight instruments (including the French WAVES and the Russian Konus) to investigate the solar wind's encounters with Earth's magnetosphere and ionosphere in order to determine the origins and three-dimensional characteristics of the solar wind. The spacecraft's original mission was to directly move to the L1 Lagrange point but because the SOHO and ACE spacecraft were directed to that location, the WIND mission was reformulated to operate for some time in a unique figure-eight-shaped elliptical orbit around Earth at 28,000 × 1.6 million kilometers, partially maintained by periodic "double flybys" of the Moon.

In this orbit, Wind was positioned so as to make use of lunar gravity assists to maintain its apogee over the day hemisphere of Earth and conduct magnetospheric observations. The closest of its 19 flybys of the Moon between 1 December 1994 and 17 November 1998 took place on 27 December 1994 at a range of 11,834 kilometers. Finally, by November 1996, Wind was in a "halo orbit" around the Sun–Earth L1 libration point where solar and terrestrial gravity are approximately equal. Parameters varied between 235 and 265 Earth radii. In this orbit, Wind measured the incoming solar wind, and magnetic fields and particles on a continuous basis, providing about an hour warning to the other ISTP-related spacecraft on changes in the solar wind. On 17 November 1998, Wind began to move into a series of "petal" orbits, designed to take it out of the ecliptic plane. Wind's trips above and below the ecliptic (up to 60°) allowed the spacecraft to sample regions of interplanetary space and the magnetosphere that had not been previously studied.

By 2004, it was back at L1 where it has remained. The original projected lifetime of the vehicle was anticipated to be three to five years but WIND continues to be largely operational in 2017, 22 years after its launch, with one instrument, the TGRS gamma-ray spectrometer turned off, and a couple of detectors on the EPACT instrument, non-functional. Current projections suggest that it will have enough fuel to remain at L1 for at least another 60 years. Despite the formal conclusion of the ISTP in December 2001, Wind continues to play a supporting role for a variety of other spacecraft supporting solar research, including Polar, Cluster, Geotail, Image, SOHO, and ACE.

SOHO

Nation: ESA and USA (2) Objective(s): Sun–Earth L1 Lagrange Point Spacecraft: SOHO Spacecraft Mass: 1,864 kg Mission Design and Management: ESA / NASA Launch Vehicle: Atlas Centaur IIAS (AC-121 / Atlas IIAS no. 8206 / Centaur II) Launch Date and Time: 2 December 1995 / 08:08:01 UT Launch Site: Cape Canaveral Air Force Station / Launch Complex 36B

Scientific Instruments:

  1. solar-ultraviolet measurements of emitted radiation experiment (SUMER)
  2. coronal diagnostic spectrometer (CDS)
  3. extreme ultraviolet imaging telescope (EIT)
  4. ultraviolet coronograph spectrometer (UVCS)
  5. large angle and spectrometric coronograph (LASCO)
  6. solar wind anisotropies experiment (SWAN)
  7. charge, element, and isotope analysis experiment (CELIAS)
  8. comprehensive suprathermal and energetic particle analyzer (COSTEP)
  9. energetic and relativistic nuclei and electron experiment (ERNE)
  10. global oscillations at low frequencies experiment (GOLF)
  11. variability of solar irradiance and gravity oscillations experiment (VIRGO)
  12. Michelson Doppler imager/solar oscillations investigation (MDI/SOI)
<!-- image -->

Results: The ESA-sponsored Solar and Heliospheric Observatory (SOHO) carries 12 scientific instruments to study the solar atmosphere, helioseismology, and the solar wind. Information from the mission has allowed scientists to learn more about the Sun's internal structure and dynamics, the chromosphere, the corona, and solar particles. The SOHO and Cluster missions, part of ESA's Solar Terrestrial Science Programme (STSP), are ESA's contributions to the International Solar Terrestrial Physics (ISTP) program, which has involved the work of other spacecraft such as Wind and ACE, which, like SOHO, operate in the vicinity of the Sun–Earth L1 point. NASA contributed three instruments on SOHO as well as launch and flight operations support. About two months after launch, on 14 February 1996, SOHO was placed at a distance of 1.5 million kilometers from Earth in an elliptical Lissajous orbit around the L1 libration point where it takes approximately six months to orbit L1 (while the L1 itself orbits the Sun every 12 months).

The spacecraft returned its first image on 19 December 1995 and was fully commissioned for operations by 16 April 1996. SOHO finished its planned two-year study of the Sun's atmosphere, surface, and interior in April 1998. Communications with the spacecraft were interrupted for four months beginning 24 June 1998, after which the spacecraft was apparently spinning, losing electrical power, and not pointing at the Sun. After intensive search efforts, by 25 September, controllers managed to regain control and return SOHO to "normal mode." Because of the failure of onboard gyros, ESA developed a special gyroless method of orientation (which used reaction wheels) that was successfully implemented beginning 1 February 1999. Barring three instruments, the spacecraft was functional and was declared operational once again by mid-October 1998.

SOHO's original lifetime was three years (to 1998), but in 1997, ESA and NASA jointly decided to prolong the mission to 2003, thus enabling the spacecraft to compare the Sun's behavior during low dark sunspot activity (1996) to the peak (around 2000). One of SOHO's most important discoveries has been locating the origin of the fast solar wind at the corners of honeycomb-shaped magnetic fields surrounding the edges of large bubbling cells located near the Sun's poles. Another has been its discovery, as of September 2015, of over 3,000 comets (more than one-half of all known comets), by over 70 people representing 18 different nations. These discoveries were made possible because of the LASCO instrument that while observing the Sun, blocked out the Sun's glare, rendering comets visible. SOHO's mission at L1 has now been extended six times, most recently in June 2013, to at least December 2016. In December 2015, SOHO marked 20 years of continuous operation, having fundamentally changed our conception of the Sun "from a picture of a static, unchanging object in the sky to the dynamic beast it is," in the words of Bernhard Fleck, the ESA project scientist for SOHO. The longevity of the mission has allowed SOHO to cover an entire 11-year solar cycle and the beginning of a new one. One of the recent highpoints of the mission was SOHO's observation of a bright comet plunging toward the Sun on 3–4 August 2016 at a velocity of nearly 2.1 million kilometers/hour.

189

Lunar Prospector

Nation: USA (72)

Objective(s): lunar orbit

Spacecraft: Lunar Prospector

Spacecraft Mass: 300 kg

Mission Design and Management: NASA / ARC

Launch Vehicle: Athena-2 (LM-004)

Launch Date and Time: 7 January 1998 / 02:28:44 UT

Launch Site: Cape Canaveral Air Force Station / SLC-46

Scientific Instruments:

    1. electron reflectometer and magnetometer (MAG/ER)
    1. gamma-ray spectrometer (GRS)
    1. neutron spectrometer (NS)
    1. alpha particle spectrometer (APS)
    1. Doppler gravity experiment (using S-band antenna) (DGE)

Results: Lunar Prospector was designed to collect data to compile the first complete compositional and gravity maps of the Moon during its planned one-year mission in lunar polar orbit. It was the third mission of NASA's Discovery Program of low-cost, highly-focused, and relatively frequent missions that were competitively selected. After two mid-course corrections, Lunar Prospector entered orbit around the Moon 105 hours after launch. Initial parameters were 92 × 153 kilometers. After two further corrections on 13 and 15 January, the spacecraft entered its operational 100 × 100-kilometer orbit at 90° inclination with a period of 118 minutes. Perhaps of most interest to scientists was to continue investigations into the signs of water ice on the Moon as found by the Clementine probe.

Page 39 of 68