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s<br />

HMM<br />

Assessment Study<br />

Report: CDF-20(A)<br />

February 2004<br />

page 79 of 422<br />

Table 2-27: Fast abort transfer characteristics<br />

The fast-abort transfer characteristics are shown in Table 2-27. The abort manoeuvre cost,<br />

despite rising for late abort, is always within the mission budget, as all propellant reserved for<br />

MOI, orbit circularization and TEI can be used for this purpose. The remaining ∆V capability<br />

after TMI is 5.2 km/s, once the MEV is discarded.<br />

The duration is counted starting from Earth escape and increase from 1 year to 1.5 years if the<br />

abort decision is delayed. In terms of life support systems, there would be no problem as the<br />

system is designed for a nominal lifetime that is longer than the duration of the abort mission in<br />

any case. The time spent in deep-space can exceed the nominal duration, but in no case should<br />

the radiation limits be exceeded.<br />

The shaded area indicates the potential problem with a late fast abort, the Earth arrival velocity is<br />

significantly larger than that in the nominal mission. This situation occurs 75 days after<br />

departure. One option here is to use the remaining ∆V capabilities to reduce the arrival velocity<br />

at Earth. If not, the ERC should be redesigned to cope with entry velocities as high as 17 km/s.<br />

This will require further study.<br />

2.7.12.1.3 Slow abort during Mars transfer<br />

The slow option retargets for a modified Mars swing-by. After that, another deep-space<br />

manoeuvre is required for retargeting to Earth arrival.<br />

Abort<br />

decision<br />

date<br />

1 May<br />

2033<br />

1<br />

August<br />

2033<br />

1<br />

October<br />

2033<br />

Abort decision date ∆V [km/s] Earth arrival date Earth arrival<br />

velocity [km/s]<br />

DSM 1<br />

22<br />

October<br />

2033<br />

23<br />

October<br />

2033<br />

24<br />

October<br />

2033<br />

∆V -1<br />

[km/s]<br />

Mars<br />

swingby<br />

DSM 2<br />

∆V-2<br />

[km/s]<br />

Total<br />

∆V<br />

[km/s]<br />

Earth<br />

arrival<br />

date<br />

Arrival<br />

hyperbolic<br />

arrival velocity<br />

[km/s]<br />

0.899 2.110 3.010 5.280<br />

0.895 25 21 2.111 3.005 28 5.284<br />

0.894<br />

October<br />

2033<br />

January<br />

2035<br />

2.110 3.004<br />

September<br />

2035<br />

Table 2-28: Slow abort transfer dependencies<br />

5.287<br />

Duration [d]<br />

1 April 2033 2.335 8 April 2034 1.9 365<br />

1 May 2033 2.447 13 April 2034 2.8 370<br />

1 June 2033 2.695 27 April 2034 4.6 384<br />

1 July 2033 2.910 13 May 2034 6.4 400<br />

1 August 2033 3.117 29 May 2034 8.1 416<br />

1 September 2033 3.323 19 June 2034 9.5 431<br />

1 October 2033 3.523 27 June 2034 10.9 445<br />

Duration<br />

[d]<br />

904

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