Aerospace and Electronic Systems - August 2018 - 19

Fowler and Dyer
Table 4.

Simulated Timeline for Landing on Europa from Initiating the Braking Maneuver to the Lander Touching Down on
Europa and the Booster and Sky Crane Affecting Jupiter
Time from
Landing (s)

Fourth-Stage Booster Maneuver

Speed
(m/s)

Altitude
(km)

Sky Crane-Lander
Maneuver

2,025

270

-

1

−354

Begin deorbit, fire fourth-stage motor

2

−204

Shut off fourth-stage motor, release
sky crane and lander to coast

353

71

Begin coast phase,
separate from booster

3

−201

Fire thrusters to move fourth-stage
booster sideways and rotate it

357

70

Coast

4

−199

Fire fourth-stage motor again

358

69

Coast

5

−179

Fourth-stage booster reaches escape
velocity

2,055

92.5

Coast

6

−101

-

485.4

26.6

Sky crane and lander
finish coasting, begin
landing sequence

7

−100

-

486.6

26.1

Fire sky crane thrusters

8

−50

-

271.5

7.04

Sky crane begins lowering
the lander

9

−1

-

0

0

Lander reaches surface

10

0

-

0

0

Sky crane releases lander

11

1

-

5

0.05

Sky crane begins escape
trajectory

12

2

-

0

0

13

63

-

2,080

52.6

Sky crane escapes Europa,
points toward Jupiter

14

64

-

2,100

54.7

Sky crane fuel runs out,
coasts toward Jupiter

15

>3.2 d

-

-

Sky crane still coasting

16

>3.8 d

-

-

Sky crane crashes into
Jupiter

Fourth-stage booster crashes into
Jupiter
-

MASS SPECTROMETER/TOF GAS CHROMATOGRAPH

DISCUSSIONS DURING MAS 2017

Understanding the chemistry and distribution of compounds on
Europa requires a sensitive instrument. Because Europa has no discernable atmosphere, the instrument needs to capture samples or
sniff diffuse fluxes of compounds. A mass spectrometer/TOF gas
chromatograph has no mobility and must have samples brought to
it. A means to acquire distant samples for measurements would be
necessary. We originally had proposed to launch a small bucket
up to 100 m away, which would scoop up small samples of ice or
minerals and then be reeled back for analysis by the mass spectrometer. A TOF gas chromatograph, the Strofio instrument, was
developed for sampling Mercury's exosphere, so the technology
exists; regardless, this instrument and the sampling-bucket mechanics would be a challenging design, and we have decided to not
include it in this proposal [38]-[45].
AUGUST 2018

Lander begins science
preparation

Discussions during MAS 2017 raised additional concerns and insights for this proposal:
C

C

C
C

C

Burst-mode data acquisition for the imagers and for the seismometers or microphones
Increased bandwidth for acoustic data to 20 kHz for seismic
recording
Fuel tradeoffs for the sky crane
Methods for guiding the burrowing or sinking of the pod
and probes
Active seismic operations with energy impulses to study the
ice and ocean layers

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