estiny+ Science Center Dust Data Archive "Helios 1,2 Data"

	Name	Last modified	Size	Description
	Parent Directory		-
	trajectory/	2026-04-01 15:19	-
	ausschnitt_tab2_ta135.txt	2019-08-01 09:52	573
	totzeit.txt	2024-08-27 12:28	616
	ausschnitt_tab3_ta135.txt	2019-08-01 09:57	843
	ausschnitt_tab1_ta135.txt	2019-08-02 08:40	896
	README	2024-08-27 12:42	4.7K
	helios_data_tab2.txt	2019-07-22 08:39	19K
	tab2.dat	2019-09-09 12:39	20K
	helios_data_tab1.txt	2020-02-28 07:02	21K
	helios_data_tab3.txt	2019-07-22 08:39	22K
	tab3.dat	2019-09-09 12:39	22K
	tab1.dat	2019-09-09 12:39	23K

Summary

This folder contains the dust data measured with Helios 1. Helios 2 did not provide any meaningful dust measurements.

The decriptions of the tables were translated from German to English based on the Appendix in Eberhard Grün's habilitation thesis (see folder 'Publications').

Entries for Table 1:

List of micrometeorites detected by Helios 1. Details can be found in Section IV.3.

• Col 1: Particle number
• Col 2: Day of year and year when the impact happened
• Col 3: Sensor which registered the impact (E: ecliptic sensor; S: south sensor)
• Cols 4 to 6: Impact speed v, and lower (v_u) and upper (v_o) uncertainty limit, unit: km/s
• Cols 7 to 9: Particle mass m, and lower (m_u) and upper (m_o) uncertainty limit, unit: gram
• Col 10: Heliocentric distance r of spacecraft at particle impact in AU
• Col 11: True anomaly angle (rl) of Helios 1 at the time of particle impact
• Col 12: Azimuth angle (apex), which is the orientation of the sensor axis projected on
to the ecliptic. An angle of 90 deg refers to the direction towards the Sun, 0 deg points perpendicular to the Sun direction in the direction of motion of Helios (apex direction). A letter 'e' behind the entry means that from the azimuth angle and the true anomaly angle alone one can derive that the particle orbit must be eccentric.
• Col 13: Total impact charge Qsp measured in the spectrum in units of 10^-13 Coulomb.
• Col 14: Data type: amplitude range of impact charge value Q_I, 'G' means protected, 'U' means unprotected data.

Entries for Table 2:

Orbital parameters based on the models including radiation pressure, details can be found in Section 6.2.

• Col 1: Particle number
• Col 2 and 3: Mean of reciprocal value of the particle semimajor axis and its uncertainty value, unit: AU
• Col 4 and 5: Mean eccentricity of particle orbit and its uncertainty value
• Col 6 and 7: Mean inclination of particle orbit and its uncertainty value, unit: degrees
• Col 8 and 9: Mean perihelion distance of particle orbit and its uncertainty value, unit: AU
• Col 10: Probability that the particle trajectory was oriented towards the Sun (entry > 0.75)
or away from the Sun (entry < 0.25) during the impact, respectively. Entries in the range 0.25 ... 0.75 mean that the particle was detected close to its perihelion or aphelion.
• Col 11: Probability that the particle trajectory was hyperbolic (i.e. eccentricity > 1). Entries in this column for a hyperbolic trajectory exceed 0.75.
• Col 12: Radiation pressure model which yields a hyperbolic particle trajectory (i.e. entry in col 11 > 0.75). '0' entries mean that the particle was on a hyperbolic trajectory based on models 0, 1 and 2. '1' entries mean that the particle trajectory is hyperbolic based on models 1 and 2. '2' means that the particle trajectory is hyperbolic based on model 2. If no entry is given, none of the radiation pressure models yields a value for Col 11 > 0.75.

Entries for Table 3:

• Col 1: Particle number
• Col 2: Total impact charge Qsp measured in the spectrum in units of 10^-13 Coulomb (repeated
from Tab. 1). An '*" indicates that the positive impact charge O_I was at the upper end of the measurement range.
• Col 3: Density. Entries 'nD' refer to 'excentric" particles with larger masses and speeds than the one corresponding to the penetration limit of particles with density 0.1 g/cm^-3, cf. Fig. 46.
• Col 4: Chemical classification. 'Ch': chondritic spectrum, 'Fe': iron-rich spectrum, 'Un': undetermined spectrum.
• Col 5 to 16: Mass spectrum. The ion charge intensity is given for 12 mass ranges between 16 u and 74 u. The ion charge intensity over the entire mass range is normalized to 1. The 12 mass ranges are: 16-20 u, 20-25 u, 25-30 u, 30-35 u, 35-40 u, 40-45 u, 45-50 u, 50-55 u, 55-60 u, 60-65 u, 65-70 u, 70-74 u.

Table "Totzeit" (Table 7 in Eberhard Grün's habilitation thesis, page 84):

The table gives the total measurement time in fractions of the total time for different kinds of events and distance range of Helios. The measurement time apply to the first 10 orbits of Helios 1 around the Sun, i.e. from 10 December 1974 to 23 February 1980.

Data types:

Q_I amplitude ranges:	1, 2, 3, 4
Protected (geschuetzt) Data:	"G"
Unprotected Data:	"U"

• Col 1 and 2: Heliocentric distance range of Helios in AU
• Col 3 to 6: Fractions of total time that is classified as measurement time.
• Col 7: Total time Helios spent in the distance interval given in Col 1, unit: s.