Transcript Баллистико-навигационное обеспечение п

Ballistics and navigation support
for the Venera-D mission
V. A. Shishov1, V. A. Stepaniants1,
A. G. Tuchin1, S. M. Lavrenov2
(1)Keldysh Institute of Applied Mathematics, Russian Academy of Sciences,
(2)Moscow State Institute of Electronics and Mathematics (Technical University)
Moscow 2012
Comparison of probable start windows by summary
costs of characteristic velocities
Arriving date
Flight durance (days)
Departure
Velocity
(km/sec)
11.01.2020
25.07.2020
196
4.677
3.483
8.160
28.10.2021
06.04.2022
160
2.800
4.760
7.560
27.05.2023
27.10.2023
153
2.573
3.695
6.268
07.12.2024
15.05.2025
159
3.295
2.686
5.981
08.06.2026
08.12.2026
183
3.857
2.989
6.846
Departure
date
9
8
7
6
5
4
3
2
1
0
2020
2021
2023
Сумма скоростей, км/с
2024
2026
Arriving
Velocity
(km/sec)
Velocity sum
(km/sec)
Isolines of the total characteristic velocities for the
2020 start window
240
12
15
Optimal date to start
11.01.2020
Transition duration
196 days
20
230
12
15
220
9
12
9
210
9
8.3
8.25
200
8.2
8.3
12
190
8.2
8.3
9
8.25
40
15
180
30
9
8.25
8.3
9
20
12
20
15
15
40
30
170
12
20
30
9
1520
40
15
40
30
20
30
20
15
12
40
160
20
40
15
150
12
20
15
20
140
22.11.2019
20.12.2019
30
12
11.01.2020
25.02.2020
По оси абсцисс – даты старта, по оси ординат – продолжительность
are on the axis
of abscissa
перелёта (в сутках). Dates
На перекрестье
красных
линий – оптимальная дата
Flight durations
are on axis of theперелёта
ordinates(196
(in days)
старта (11.01.2020)
и продолжительность
суток).
Main ballistics tasks to be solved
during the Venera-D mission
• Pointing for the on-Earth tracking stations
• Trajectory measurement raw processing
• Determination and forecast of the SC motion
parameters
• Maneuver and adjustment calculations
• Data calculations for the on-board control
system
• Scientific program providing
Flight trajectory adjustments
• Insertion into transfer orbit after motion on the orbit around
the Earth
• The first correction is performed on the seventh day of the
flight.
• The second correction is performed four days prior to the
Venus approach. After performing the second correction and
the DM separation the SC withdrawal maneuver is performed.
• The third motion correction of the SC is implemented one day
before approaching for the trim purpose.
• The capture maneuver is performed at the outgoing hyperbola
pericenter and the SC goes to the high eccentricity orbit
around Venus.
Maneouver and correction execution errors
1. Errors of the flight path transfer impulse (the first)
performance are 0.2% by value and 0.7° by
direction.
2. Errors of the correction impulses (the second etc.)
and the withdrawal maneouver are 0.5 m/sec by
value and 0.7° by direction.
Orbital measurements in the project
Venera-D carry on
1. up to 2 Mkm distances from tracking stations in Baikonur and Bear
Lakes with Spectr-X facilities (antenna THA-57,diameter=12.5m);
2. at distances more than 1.5 Mkm from tracking stations in
Ussuriisk(antenna P-2500, diameter=70 m) and Bear Lakes (antenna
TNA-1500, diameter=64 m) equipped with large radars.
Radiated frequency: 7.1–7.2 GHertz .
On-board frequency conversion coefficient: 880/749.
Zone of unambiguous measurement of the range (in the slant distance sense):
1023 km.
Measurement errors: 20 m by range, 0.2 mm/sec by range rate.
Flight trajectory measurement program
• On the path part prior to the first correction the measurements
are carried on daily, four tracking stations being on duty up to
distances 2 Mkm, two ones being on service after this
threshold.
• On the path part after the first correction the measurements are
carried on every four days, two tracking stations in the Bear
Lakes and Ussuriisk being at work.
• The measurements are carried on by two tracking stations
daily during two weeks prior to the second correction
fulfillment.
• And after second correction two tracking stations do
measurements one time weekly.
The scheme of the Descent Module
(DM) delivery
• One should provide with the prescript Venus atmosphere enter angle, illumination
constraints and radio vision conditions from the on-ground tracking stations as well.
• These circumstances are ensured by two corrections on the flight trajectory: namely on
the seventh day of flight and the four days prior to entering Venus atmosphere.
•The DM escapes the main SC and does autonomous flight after the second correction.
•The Orbital Apparatus (OA) performs the withdrawal maneuver and then the trim
maneuver to transfer at the outgoing hyperbola with given inclination (90º) and given
pericenter height (250 km) where it get the braking impulse to go on the elliptical orbit
around Venus. With all that the ОА should reach the minimum distance up to Venus the
four hours earlier than the DM would reach its atmosphere.
•In entering the Venus atmosphere the DM has to connect with the OA which would
retransmit the telemetrical flow to the Earth.
The scheme of the Descent Module
(DM) delivery
Ballistics destination areas on the Venus surface
in 2020 – 2026 years
2020 г
2024 г
2021 г
2023 г
2026 г
Dependence of angles the Earth-Decent Module-Venus
(E-L-V) and the Sun-Decent Module-Venus (S-L-V)
from landing longitudes for 2020 year
The period options for the main SC orbits and
for the subsattellite orbits
№
The subsattellite orbit period,
(hours)
The main SC orbit period
(hours)
1
48
24
2
24
48
3
24
24
4
12
12
Option 1. The main SC orbit elements after setting in
the Venus orbit
Parameter
Semiaxis ( tkm)
Eccentricities
Inclination ( degrees)
Value
62.633609
0.899
90.0
Longitude of the ascending node (degrees)
240.2
Argument of the pericenter (degrees)
334.4
Mean motion (n) rad/tsec
Period (hours)
Distance at the pericenter (tkm)
Height at the pericenter (km)
Distance at apocenter (tkm)
Height at apocenter (km)
0.03636
48.0
6.301876
249.983
118.965344
112913.450640
Latitude of the under-satellite point (degrees)
–25.578
Longitude of the under-satellite point (degrees)
240.258
Energy costs of the SC to maneuver on
the Venus satellite orbits (VSO)
• The transition impulse module to the VSO is equal to
648 m/sec.
• The transition impulse module from the two days
orbit period to the one day orbit period is equal to
158 m/sec.
The SC orbit motion determination on the VSO
Range and range rate
measurements
Line of sight
The Earth Tracking
station
Possible change of the SC apocenter
Enumeration of error sources for the SC motion
and the count model
• Insufficient accuracy for the Venus gravity field
taken into account for fast operative work ; the
NASA RS-SHTJV360 gravity model has order
360x360;
• Availability of the unaccounted micro-accelerations
because of attitude engine burns;
• Inaccurate accounting of the solar radiation pressure
influence
• Inexactness in the relative motion of Venus to the
Earth
Conclusions
1. With optimizing mission energy costs we get that the Decent
Module area location on Venus turned out to be off direct
radiovision from the Earth and isn’t illuminated by the Sun.
Hence telemetry from Decent Module has to communicate
through the Orbital Craft and the Decent Module performance
capacity has to maintain by inner source.
2. Changing in the ballistics scheme to ensure the sharp
navigation calls for additional energy costs.
3. It is advisable to construct the task of joint determination for
motion parameters of the SC, Venus and the Earth within a single
dynamical model.