Vesta mission
Encyclopedia
The Soviet Union was planning a multiple asteroid flyby mission in the 1980s.
The Vesta mission would have consisted of two identical probes (just like earlier Soviet Venus missions), to be launched in 1991. Similar to the Vega program
, each spacecraft would deploy one or more landers or balloons into the Venusian atmosphere, and then proceed to its next target.
At Venus, a French satellite dedicated to asteroid flybys would be released.
It would return to us for an Earth swing-by, and then reach about 3-3.3 AUs from the Sun.
There they would fly by some smaller asteroids, and Vesta, if possible, with a small probe landing there.
The exact targets would depend on the launch date. In the initial 1985 study, 2700 possible trajectories were analyzed for a launch date in 1991/1992. Considering all constraints, about 12 candidate trajectories were selected. Of course, the two identical spacecraft could choose different trajectories and targets. These included 5 Astraea
, 53 Kalypso
, 187 Lamberta
, 453 Tea
, 1335 Demoulina
and 1858 Lobachevskij
, and comet Encke
.
Visiting at least one Apollo-Amor (Earth-nearing) asteroid was also given a preference.
Preliminary studies call for at least the following scientific instruments to be included:
Possible further instrumentation:
Onboard memory would be about 240 Mbits. Images at closest approach (~500 km) could have a resolution of 10 m/pixel. Worst case downlink rate is 600 bit/second (if not using Deep Space Network
(DSN)). The scientific payload is about 100 kg. The spacecraft has 750 kg dry mass, and carries 750 kg propellants, and possibly a 500 kg penetrator. 20 square meters of solar panels provide 350 Watts of power.
If DSN support could be obtained, Doppler tracking of the Vesta spacecraft's movement can be used to accurately determine the mass of the encountered bodies. In the other case, another possibility was considered: releasing a test mass, and observing its movement near the target asteroid.
The spacecraft's structure is derived from telecommunication satellites (INMARSAT
), having the required mass, volume, and delta-v
capabilities (3-axis stabilized, with a pointing platform with 2 axes of freedom for scientific instruments).
Nevertheless, 3 possible trajectories were designed, with two Mars gravity assists.
A single Mars swing-by is also possible, but the double gravity assist increases the mass budget of the spacecraft by 30%, at the cost of an additional 1.8 year in travel time to the asteroid belt. The following trajectories are for the 1994 launch window. The size and type of each asteroid is also shown here:
Trajectory 1:
Total delta-v: 450 m/s
Trajectory 2:
Total delta-v: 1150 m/s
Trajectory 3:
Total delta-v: 350 m/s
In other studies 11 Parthenope
, 19 Fortuna
and 20 Massalia
were also considered.
The Vesta mission would have consisted of two identical probes (just like earlier Soviet Venus missions), to be launched in 1991. Similar to the Vega program
Vega program
The Vega program was a series of Venus missions which also took advantage of the appearance of Comet Halley in 1986. Vega 1 and Vega 2 were unmanned spacecraft launched in a cooperative effort among the Soviet Union and Austria, Bulgaria, Hungary, the German Democratic Republic, Poland,...
, each spacecraft would deploy one or more landers or balloons into the Venusian atmosphere, and then proceed to its next target.
At Venus, a French satellite dedicated to asteroid flybys would be released.
It would return to us for an Earth swing-by, and then reach about 3-3.3 AUs from the Sun.
There they would fly by some smaller asteroids, and Vesta, if possible, with a small probe landing there.
The exact targets would depend on the launch date. In the initial 1985 study, 2700 possible trajectories were analyzed for a launch date in 1991/1992. Considering all constraints, about 12 candidate trajectories were selected. Of course, the two identical spacecraft could choose different trajectories and targets. These included 5 Astraea
5 Astraea
5 Astraea is a large main-belt asteroid. Its surface is highly reflective and its composition is probably a mixture of nickel-iron with magnesium- and iron-silicates....
, 53 Kalypso
53 Kalypso
53 Kalypso is a large and very dark main belt asteroid. It was discovered by Robert Luther on April 4, 1858 at Düsseldorf. It is named after Calypso, a sea nymph in Greek mythology, a name it shares with Calypso, a moon of Saturn.- References :...
, 187 Lamberta
187 Lamberta
187 Lamberta is a large and very dark main-belt asteroid. It has a composition of primitive carbonaceous materials.It was discovered by J. Coggia on April 11, 1878. It was the second of his five asteroid discoveries. It is named after the astronomer Johann Heinrich Lambert....
, 453 Tea
453 Tea
453 Tea is an S-type asteroid belonging to the Flora family in the Main Belt. Its diameter is about 21 km and it has an albedo of 0.183 . Its rotation period is 6.4 hours....
, 1335 Demoulina
1335 Demoulina
1335 Demoulina is a main-belt asteroid discovered on September 7, 1934 by Reinmuth, K. at Heidelberg. It rotates slowly, with a spin period of 74.86 hours.- External links :*...
and 1858 Lobachevskij
1858 Lobachevskij
1858 Lobachevskij is a main-belt asteroid discovered on August 18, 1972 by L. Zhuravleva at Nauchnyj.It is named for mathematician Nikolai Lobachevsky.- External links :...
, and comet Encke
Comet Encke
Comet Encke or Encke's Comet is a periodic comet that completes an orbit of the Sun once every three years — the shortest period of any known comet...
.
VESTA spacecraft design
Around 1985 Vesta was changed to be a Mars mission, with the asteroid-part unchanged. Detailed studies indicate each probe would have visited four small bodies, including asteroids belonging to different classes - providing a representative sample of the diversity of asteroids - and probably one or two comets as well.Visiting at least one Apollo-Amor (Earth-nearing) asteroid was also given a preference.
Preliminary studies call for at least the following scientific instruments to be included:
- a wide angle camera (~6.5° field of view, 512x512 pixel CCD)
- a narrow angle camera (~0.5° field of view, 512x512 pixel CCD - 3.9 arcsec/pixel)
- a near-infrared spectrometerSpectrometerA spectrometer is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. The variable measured is most often the light's intensity but could also, for instance, be the polarization...
(measuring between 0.5-5 micrometers with lambda/delta lambda = 50, 5 arcminutes per pixel)
Possible further instrumentation:
- UV spectrometer (for imaging during a comet flyby)
- radar altimeter/radiometer
- a dust detector
- ion or neutral gas detector
Onboard memory would be about 240 Mbits. Images at closest approach (~500 km) could have a resolution of 10 m/pixel. Worst case downlink rate is 600 bit/second (if not using Deep Space Network
Deep Space Network
The Deep Space Network, or DSN, is a world-wide network of large antennas and communication facilities that supports interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the solar system and the universe, and supports selected...
(DSN)). The scientific payload is about 100 kg. The spacecraft has 750 kg dry mass, and carries 750 kg propellants, and possibly a 500 kg penetrator. 20 square meters of solar panels provide 350 Watts of power.
If DSN support could be obtained, Doppler tracking of the Vesta spacecraft's movement can be used to accurately determine the mass of the encountered bodies. In the other case, another possibility was considered: releasing a test mass, and observing its movement near the target asteroid.
The spacecraft's structure is derived from telecommunication satellites (INMARSAT
Inmarsat
Inmarsat plc is a British satellite telecommunications company, offering global, mobile services. It provides telephony and data services to users worldwide, via portable or mobile terminals which communicate to ground stations through eleven geostationary telecommunications satellites...
), having the required mass, volume, and delta-v
Delta-v
In astrodynamics a Δv or delta-v is a scalar which takes units of speed. It is a measure of the amount of "effort" that is needed to change from one trajectory to another by making an orbital maneuver....
capabilities (3-axis stabilized, with a pointing platform with 2 axes of freedom for scientific instruments).
Trajectory
The Mars gravity assist constrain the possible trajectories. The asteroid penetrator also imposes limits on the speed of the approach of the target asteroid (less than 4 km/s).Nevertheless, 3 possible trajectories were designed, with two Mars gravity assists.
A single Mars swing-by is also possible, but the double gravity assist increases the mass budget of the spacecraft by 30%, at the cost of an additional 1.8 year in travel time to the asteroid belt. The following trajectories are for the 1994 launch window. The size and type of each asteroid is also shown here:
Trajectory 1:
- launch from Earth
- Mars gravity assist
- flyby of 2335 James2335 James2335 James is a Mars-crossing asteroid discovered on October 17, 1974 by E. F. Helin at Palomar.- External links :*...
(a 10 km X-type asteroid) (an Amor-asteroid) - Mars gravity assist
- 109 Felicitas109 Felicitas109 Felicitas is a dark and fairly large main-belt asteroid. It was discovered by C. H. F. Peters on October 9, 1869, and named after Felicitas, the Roman goddess of success. The only observed stellar occultation by Felicitas is one from Japan .-References:...
(C-type, 76 km) - 739 Mandeville739 Mandeville-External links:*...
(EMP(?) type, 110 km) - 4 Vesta4 VestaVesta, formally designated 4 Vesta, is one of the largest asteroids, with a mean diameter of about . It was discovered by Heinrich Wilhelm Olbers on March 29, 1807, and is named after the Roman virgin goddess of home and hearth, Vesta....
(V-type, or Vestoid. Has a diameter of 570 km) flyby with 3.5 km/s. A penetrator is released.
Total delta-v: 450 m/s
Trajectory 2:
- launch from Earth
- Mars gravity assist
- flyby of the P/Tritton short period comet
- Mars gravity assist
- 2087 Kochera 2087 Kochera2087 Kochera is a main-belt asteroid discovered on December 28, 1975 by P. Wild at Zimmerwald.- External links :*...
(30 km?) - 1 Ceres1 CeresCeres, formally 1 Ceres, is the smallest identified dwarf planet in the Solar System and the only one in the asteroid belt. With a diameter of about 950 km, Ceres is by far the largest and most-massive asteroid, comprising about a third of the mass of the asteroid belt. Discovered on 1 January 1801...
(flyby & releasing a penetrator)
Total delta-v: 1150 m/s
Trajectory 3:
- launch from Earth
- Mars gravity assist
- 1204 Renzia1204 Renzia1204 Renzia is a Mars-crossing asteroid discovered on October 6, 1931 by K. Reinmuth at Heidelberg.- External links :*...
(10 km?) (an Amor-asteroid) - Mars gravity assist
- 435 Ella435 Ella435 Ella is a typical Main belt asteroid.It was discovered by Max Wolf and A. Schwassmann on September 11, 1898 in Heidelberg....
(U type, 30 km) - 46 Hestia46 Hestia46 Hestia is a large, dark main-belt asteroid. It is also the primary body of the Hestia clump, a group of asteroids with similar orbits.Hestia was discovered by N. R. Pogson on August 16, 1857, at the Radcliffe Observatory, Oxford. Pogson awarded the honour of naming it to William Henry Smyth,...
(F type, 165 km) - 135 Hertha135 Hertha135 Hertha is a large main-belt asteroid. Named Hertha, another name for Nerthus, a Germanic fertility goddess. It orbits among the Nysa asteroid family but its classification as an M-type asteroid does not match the more common F-type asteroid for this family, suggesting that it may be an interloper...
(M type, 80 km)
Total delta-v: 350 m/s
In other studies 11 Parthenope
11 Parthenope
11 Parthenope is a large, bright main-belt asteroid.Parthenope was discovered by Annibale de Gasparis on May 11, 1850, the second of his nine asteroid discoveries. It was named after one of the Sirens in Greek mythology, said to have founded the city of Naples...
, 19 Fortuna
19 Fortuna
19 Fortuna is one of the largest main-belt asteroids. It has a composition similar to 1 Ceres: a darkly colored surface that is heavily space-weathered with the composition of primitive organic compounds, including tholins....
and 20 Massalia
20 Massalia
20 Massalia is a large and fairly bright main-belt asteroid. It is also the largest member of the Massalia family of asteroids. Its name is the Greek name for Marseille, the city from which one of the two independent co-discovers, Jean Chacornac, first sighted it.- Characteristics :Massalia is an...
were also considered.