Presentation of Team 8

Prof. Tang Guojin Prof. Luo Yazhong

Lect. Huang Haibing He Boyong Zhu Yuehe

March 6th, 2015, Roma, Italy

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“Head” trajectory

“Middle” trajectories

“Tail” trajectories

Difficulties

“Head” trajectory：candidates range from 2AU~3AU;

“Middle” trajectories：more than 16000 asteroids, less

than 40 are needed, visit sequence;

“Tail” trajectories：which is the active craft, mother ship

or probe? or both?

“Head” trajectory

Scheme 1：the mother ship with three probes

transfers to a good orbit first, then releases the probes

at proper time;

Scheme 2：the combined craft rendezvouses with an

asteroid first, then releases the probes at proper time;

(hard to design the good orbit)

(specific target，count as first visited asteroid)

Preliminary filtration according to the orbit elements

semi-major axis (a)：< 2.5 AU;

eccentricity (e)：< 0.2;

Inclination (i)：< 10°;

More than 16000 candidates→ about 3000 asteroids

“Middle” trajectories

“Middle” trajectories

Determine sequence using the branch and bound method

1st

2nd

3rd

Lambert transfer,

convert later;

Stay 30 days;

: < 250 days;

: < 1.5-2.5 km/s; V∆T∆

Type 1：mother ship picks three probes;

Type 2：three probes rendezvous with the mother ship;

Type 3：mother ship and probes all maneuver;

“Tail” trajectories

mV∆

Mother shipProbe 1 Probe 2 Probe 3

mV∆ mV∆

mV∆1pV∆

1pV∆

2pV∆

2pV∆

3pV∆3pV∆

1 2 3 0p p pV V V∆ = ∆ = ∆ =

0mV∆ =

Scheme 1：three probes fly to and stay on the same asteroid;

Scheme 2：two stay on the same asteroid, one flies out;

Scheme 3：three probes all fly out from the last asteroids;

“Tail” trajectories

mV∆

Mother shipProbe 1 Probe 2 Probe 3

mV∆ mV∆

mV∆1pV∆

1pV∆

2pV∆

2pV∆

3pV∆3pV∆

“Head” trajectory: three-impulse transfer;

“Middle” trajectories: optimize each long-chain based on the determined sequence;

“Tail” trajectories: fully use mother ship’s fuel;

Convert impulsive trajectories to the low-thrust trajectories using direct shooting method and SQP;

Optimization tool: evolution algorithms (GA, DE);

Optimization

-3 -2 -1 0 1 2 3-3

-2

-1

0

1

2

3

X/AU

Y/A

UThe Trajectory of Mother Ship

2. Impulse 1

6. Release probe3

8. Impulse 4

3. Impulse 2rendezvous with Asteroid Zoya

4. Release probe1

1. Departure

7. Impulse 3Leave Asteroid Zoya

11. Rendezvous with probe3

10. Impulse 6rendezvous with probe2

5. Release probe2

9. Impulse 5rendezvous with probe1

-3 -2 -1 0 1 2 3-3

-2

-1

0

1

2

3

X/AU

Y/A

UThe Trajectory of Probe1

1. Released from mother ship10. Rendezvous with Ambartsumian

2. Rendezvous with Polly

7. Rendezvous with Nakamura

5. Rendezvous with 1998 XR28

11. Rendezvous with mother ship

4. Rendezvous with Armandhammer

3. Rendezvous with 1999 NH49

8. Rendezvous with 1985 PC

9. Rendezvous with Kadota

6. Rendezvous with Sabrina-John

-3 -2 -1 0 1 2 3-3

-2

-1

0

1

2

3

X/AU

Y/A

UThe trajectory Of Probe2

1. Released from mother ship2. Rendezvous with Hornstein

4. Rendezvous with Leonce

9. Rendezvous with 1992 NM

8. Rendezvous with Marilyn

10. Rendezvous with mother ship

6. Rendezvous with Sevastopol

3. Rendezvous with Fennimore5. Rendezvous with Crabbegat

7. Rendezvous with Atsushi

-3 -2 -1 0 1 2 3-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

X/AU

Y/A

U

The Trajectory of Probe3

10. Rendezvous with Sanders

11.Rendezvous with mother ship

1. Released from mother ship (Zoya)

3. Rendezvous with Dikan'ka

4. Rendezvous with Kristensen

2. Rendezvous with Koremori

5. Rendezvous with Photographica

9. Rendezvous with Kreisau

7. Rendezvous with 1998 EK8

6. Rendezvous with 2000 UZ103

8. Rendezvous with 1135 T-3

Preliminary filtration according to the asteroids’ orbit

elements may not be an effect and reliable approach;

It should be more automatic when determining the

asteroids sequence;

Parallel search should be further improved;

Lessons