An insertion burn at local noon has the advantage that the spacecraft is kicked into a 1An insertion burn at local noon has the advantage that the spacecraft is kicked into a 11 1 resonant orbit, with an inexpensive recovery manoeuvre, if the insertion burn fails. resonant orbit, with an inexpensive recovery manoeuvre, if the insertion burn fails. However this was disregarded for thermal reason. However this was disregarded for thermal reason.

HYPERBOLIC APPROACHHYPERBOLIC APPROACH

BepiColombo is the ESA cornerstone mission to BepiColombo is the ESA cornerstone mission to Mercury. The launch of the spaceprobe is foreseen for Mercury. The launch of the spaceprobe is foreseen for the year 2012. The two elements of BepiColombo, a the year 2012. The two elements of BepiColombo, a planetary orbiter (MPO) and a magnetospheric orbiter planetary orbiter (MPO) and a magnetospheric orbiter (MMO), will reach their final destination in late 2016. In (MMO), will reach their final destination in late 2016. In its long interplanetary trip, BepiColombo will exploit its long interplanetary trip, BepiColombo will exploit low-thrust arcs provided by the Solar Electric low-thrust arcs provided by the Solar Electric Propulsion Module (SEPM), as well as swingbys at the Propulsion Module (SEPM), as well as swingbys at the Moon, Earth, Venus (twice), and Mercury (twice). Moon, Earth, Venus (twice), and Mercury (twice).

THE BEPICOLOMBO MISSION TO MERCURYTHE BEPICOLOMBO MISSION TO MERCURY

AADVANCED DVANCED TTOPICS IN OPICS IN AASTRODYNAMICSSTRODYNAMICSBarcelona, July 5-10, 2004Barcelona, July 5-10, 2004

USE OF GRAVITATIONAL CAPTUREUSE OF GRAVITATIONAL CAPTUREFOR THE BEPICOLOMBO MISSION TO MERCURYFOR THE BEPICOLOMBO MISSION TO MERCURY

Stefano Campagnola, Rüdiger JehnStefano Campagnola, Rüdiger JehnMission Analysis Office ESA/ESOC, Darmstadt, GermanyMission Analysis Office ESA/ESOC, Darmstadt, Germany

Stefano.Campagnola@esa.intStefano.Campagnola@esa.int

GRAVITATIONAL CAPTUREGRAVITATIONAL CAPTURE

The use of the gravitational capture is now considered. Performing extended low-thrust arcs until some 30 days before arrival, the spacecraft will The use of the gravitational capture is now considered. Performing extended low-thrust arcs until some 30 days before arrival, the spacecraft will attain very low relative velocity with respect to Mercury, and will orbit temporarily around it before escaping again as a result of the Sun attain very low relative velocity with respect to Mercury, and will orbit temporarily around it before escaping again as a result of the Sun

perturbation. Two interesting cases are presented here. More results and further analysis will soon be published.perturbation. Two interesting cases are presented here. More results and further analysis will soon be published.

Launch DateLaunch Date 3 May 20123 May 2012Lunar Flyby DateLunar Flyby Date 23 Jul 201223 Jul 2012Arrival DateArrival Date 26 Nov 201626 Nov 2016SEP consumptionSEP consumption 6.46 (7.65*) km/s6.46 (7.65*) km/sCH consumptionCH consumption 0.355 (0.398*) km/s0.355 (0.398*) km/sMaximum Thrust (SEPM) Maximum Thrust (SEPM) 400 mN400 mNCruise TimeCruise Time 4.35 years (1589 d)4.35 years (1589 d)

Initially the optimum trajectory was Initially the optimum trajectory was determined for a hyperbolic approach. determined for a hyperbolic approach. However a failure of the chemical insertion However a failure of the chemical insertion burn would result in a failure of the burn would result in a failure of the mission, as the inadvertent flyby would mission, as the inadvertent flyby would send the spacecraft away from Mercury. send the spacecraft away from Mercury. Tab 2 : Summary of the hyperbolic approachTab 2 : Summary of the hyperbolic approach

* including navigation, margin, corrections for non-nominal arrival conditions* including navigation, margin, corrections for non-nominal arrival conditions

At arrival to Mercury, a chemical insertion manoeuvre will be performed to insert At arrival to Mercury, a chemical insertion manoeuvre will be performed to insert the two elements into the MMO target orbit (400x12000 km), from where MPO the two elements into the MMO target orbit (400x12000 km), from where MPO will eventually be inserted into its target orbit (400x1500 km)will eventually be inserted into its target orbit (400x1500 km)

f f MERCURYMERCURY at arrival at arrival 60°<60°<ffMEME<120°, <120°, 240°<240°<ffMEME<300°<300°

i MMO / MPO i MMO / MPO 9090°°

MMO / MPOMMO / MPO 00°°

h periherm MMO / MPOh periherm MMO / MPO 400 km400 kmh apoherm MMOh apoherm MMO 12000 km12000 kmh apoherm MPO h apoherm MPO 1500 km1500 kmMMO MMO 178178°°

MPO MPO 196196°°

Tab 1 : Target orbits for MMO and MPOTab 1 : Target orbits for MMO and MPO

Fig 3 : Hyperbolic approach and target orbitsFig 3 : Hyperbolic approach and target orbits

Fig 2 : Definition of the Fig 2 : Definition of the angleangle

Giuseppe “Bepi” ColomboGiuseppe “Bepi” Colombo

Fig 4 : Incoming and recovery trajectories for case A Fig 4 : Incoming and recovery trajectories for case A in a Mercury equatorial reference frame (upper left and lower right) and in a rotating reference frame (lower left) in a Mercury equatorial reference frame (upper left and lower right) and in a rotating reference frame (lower left)

CASE A (left)CASE A (left)Nominal Arrival Date:Nominal Arrival Date:

5 Jan 20175 Jan 2017MJD2000 6214.4 MJD2000 6214.4

Arrival osculating orbit:Arrival osculating orbit:400x200000 km400x200000 kmCASE B (right)CASE B (right)

Nominal Arrival Date:Nominal Arrival Date:5 Jan 20175 Jan 2017

MJD2000 6214.9 MJD2000 6214.9 Arrival osculating orbit:Arrival osculating orbit:

400x180000 km400x180000 km

Fig 5 : Incoming and recovery trajectories for case B Fig 5 : Incoming and recovery trajectories for case B in a Mercury equatorial reference frame (upper right and lower left) and in a rotating reference frame (lower right) in a Mercury equatorial reference frame (upper right and lower left) and in a rotating reference frame (lower right)

To the Sun

1st VRec (~1 m/s)

2nd VRec (~40 m/s)

To the Sun

1st VRec (~1 m/s)

2nd VRec (~3 m/s)

3rd VRec (~5 m/s)

Fig 1 : BepiColombo Interplanetary trajectory Fig 1 : BepiColombo Interplanetary trajectory with the swingby dateswith the swingby dates

(1) Moon (1) Moon 23 Jul 201223 Jul 2012

(2) Earth(2) Earth1 Nov 20131 Nov 2013

(3) Venus1(3) Venus127 Mar 201427 Mar 2014

(4) Venus2(4) Venus27 Nov 20147 Nov 2014

(5) Mercury1(5) Mercury128 Jun 201628 Jun 2016

(6) Mercury2(6) Mercury27 Aug 20167 Aug 2016

ArrivalArrival26 Nov 201626 Nov 2016