The European Space Agency's Rosetta mission involved sending a spacecraft on a decade-long journey to rendezvous with and study comet 67P/Churyumov–Gerasimenko. In 2014, Rosetta deployed the Philae lander, which achieved the first controlled landing on a comet nucleus. Philae transmitted data from the surface for 60 hours before losing power. Analysis showed the surface was harder than expected. Future contact may be possible if the comet brings Philae close enough to the sun to recharge its batteries in August 2015. The mission has provided the first detections of organic molecules on a comet, offering clues about the early solar system.

1. Journey of Rosetta to comet 67P

2.  Satellite communication is the use of artificial satellites to provide
communication links between various points on Earth
 It plays a vital role in the global telecommunications system
 Approximately 2,000 artificial satellites orbiting Earth relay analog
and digital signals carrying voice, video, and data to and from one or
many locations worldwide.
 Satellite communication has two main components:
1. The ground segment, which consists of fixed or mobile transmission,
reception, and ancillary equipment.
2. The space segment, which primarily is the satellite itself.
 A typical satellite link involves the transmission or uplinking of a
signal from an Earth station to a satellite.
What is Satellite Communication?

3.  The satellite then receives and amplifies the signal and
retransmits it back to Earth, where it is received and re-amplified
by Earth stations and terminals.
 Satellite receivers on the ground include direct-to-home (DTH)
satellite equipment, mobile reception equipment in aircraft,
satellite telephones, and handheld devices.

4.  Apart from the satellites that revolve around earth serving the purpose of
communication and weather updates, there are satellites/ space probes sent
into the space to study about other planets and comets.
So, What’s new? (Interstellar :P)
 The Picture shows a space
probe which made halfway
through Pluto in record time
 One among such Space
probe’s is Rosetta-Philae, a
comet lander by European
Space Agency.

5.  Comets are the primitive building blocks of
the Solar System, left over from a planet-
building time when our Sun was just a disc
of spinning dust and gas.
 Made of ice, dust and small rocky particles,
it is likely they delivered the first water to
Earth and may have even seeded the planet
with the building blocks for life.
 Cometary dust brought back to Earth by
NASA’s stardust mission contained glycine,
an amino acid that is a basic part of life.
 The comet and spaceship now lie 405 million
kilometres from Earth, about half way
between the orbits of Jupiter and Mars,
rushing towards the inner Solar System at
nearly 34175 miles per hour.
Comets

6. Rosetta- Philae comet lander
 Rosetta is a robotic space probe
built and launched by the European
Space Agency which is performing
a detailed study of comet
67P/Churyumov–Gerasimenko
(67P) with both an orbiter and a
lander module Philae.
 On 12 November 2014, the lander
achieved the first-ever controlled
touchdown on a comet nucleus
 Philae '​s mission was to land
successfully on the surface of a
comet, attach itself, and transmit
data from the surface about the
comet's composition.

7. We’re here – when Rosetta meets 67P
 Catch up finally
The spacecraft Rosetta is trying to catch a comet. Today, after a decade long
journey, it finally reached caught up with 67P/Churyumov-Gerasimenko
"After ten years, five months and four days travelling towards our
destination, looping around the Sun five times and clocking up 6.4 billion
kilometres, we are delighted to announce finally 'we are here',"
said Jean-Jacques Dordain, the director general of the European Space
Agency.
 First spacecraft
"Europe's Rosetta is now the first spacecraft in history to rendezvous with a comet,
a major highlight in exploring our origins. The discoveries can begin."

9.  Not a straight forward journey
Rosetta has already been travelling for more than a decade after the craft was
launched on March 2 2004, from Kourou, French Guiana, but its journey has
been less than straightforward.
 Take a sling shot
The comet is moving far faster than speeds which could ever be achieved by a
spacecraft leaving Earth. So the craft has spent the time since, using the
gravitational pull of the Earth and Mars to act as a sling shot and allow it to
pick up acceleration.
 Crucial speed: To Jupiter in a stretch
When it reached the crucial speed in July 2011 the Rosetta was put into deep-
space hibernation for the coldest, most distant leg of the journey as it travelled
some 497 million miles from the Sun, close to the orbit of Jupiter as the comet
headed into outer Solar System.
GLIMPSE OF THE JOURNEY

11. LANDING:
 Philae remained attached to the Rosetta spacecraft after rendezvousing with
comet 67P/Churyumov–Gerasimenko until 12 November 2014.
 Nucleus : Agilkia (“Site J”)
On 15 September 2014, ESA announced "Site J" on the smaller lobe of the
comet as the lander's destination. Following an ESA public contest in October,
Site J was renamed Agilkia in honour of Agilkia Island.
 Go/NoGo Checks:
A series of four Go/NoGo checks were performed 11–12 November 2014. One
of the final tests before detachment from Rosetta showed that the lander's cold-
gas thruster was not working correctly, but the "Go" was given anyway, as it
could not be repaired.
 Philae detached from Rosetta on 12 November 2014 at 08:35 UTC, landing
seven hours later at 15:35.
 Landing Confirmed:
A confirmed landing signal was received at Earth communication stations 28
light-minutes away at 16:03 UTC

12. Rosetta Spacecraft Mission – Philae Comet Lander

13. Landing and operations on surface
 Soft Landing:
An analysis of telemetry indicated that the landing was softer than expected, that
the harpoons had not deployed upon landing, and that the thruster had not fired.
 The harpoon propulsion system contained 0.3 grams of nitrocellulose, which
was shown by Copenhagen Suborbitals in 2013 to be unreliable in a vacuum.
 Further analysis indicated that the lander had bounced twice and landed three
times; the first bounce (with a velocity of 0.38 m/s, compared to 1 m/s
incoming) lasted two hours and may have been 1 km (0.62 mi) high, the second
(at 0.03 m/s) lasted seven minutes.
 The initial bounce was the largest in history at 1 kilometre (0.62 mi), because
of the very low gravity on the comet.

15.  Philae sits askew on all three
legs, leaning on a rock in partial
darkness as much as a kilometre
from the first landing spot at an
unknown location.
 The initial battery charge was
designed to power the
instruments for about 60 hours.
The ESA had hoped that the
battery could be partially
recharged by the solar panels
attached to the outside of the
lander, but the limited sunlight
(1.5 hours per 12-hour comet
day) at the landing site is
inadequate to maintain Philae's
activities, at least in this region
of the comet's orbit

16. Final operations
 On the morning of 14 November 2014, the battery charge was estimated to be
only enough for continuing operations for the remainder of the day.
 After first obtaining data from instruments whose operation did not require
mechanical movement, comprising about 80% of the planned initial science
observations, both the MUPUS soil penetrator and the SD2 drill were
commanded to deploy. Subsequently, MUPUS data as well as COSAC and
Ptolemy data were returned. A final set of CONSERT data was also
downlinked towards the end of operations.
 During the evening's transmission session, the lander was lifted 4 cm and
rotated 35° in an attempt to position the solar panels more favorably for the
future.

17. Philae lander detects organic molecules on surface
of comet
 Spacecraft beams back
evidence of carbon and
hydrogen that could
provide clues about
origins of life on Earth
 Philae worked for more
than 60 hours on the
comet, which is more than
500m miles from Earth,
before hibernating.
 The Philae lander has
found organic molecules,
which are essential for life
on the surface of the
comet where it touched
down last week.

18.  Organic molecules, which are chemical compounds that contain carbon
and hydrogen, form the basic building blocks of all living organisms on
Earth.
 They can take many forms from simple small molecules like methane gas
to complex amino acids that make up proteins.
 In a desperate attempt to get as much science from the lander as possible
before its meagre battery reserves ran out, scientists deployed a drill to
bore down into the comet surface.
 But other findings from instruments on the lander, which were beamed
back shortly before it powered down into a hibernation mode, suggest that
the comet is largely composed of water ice that is covered in a thin layer
of dust.

19.  Contact lost:
Shortly afterwards, electrical power dwindled rapidly and all instruments
were forced to shut down. The downlink rate finally slowed to a trickle before
coming to a stop. Contact was lost at 00:36 UTC on 15 November.
 DLR's lander manager Stephan Ulamec stated:
Prior to falling silent, the lander was able to transmit all science data
gathered during the First Science Sequence. ... This machine performed
magnificently under tough conditions, and we can be fully proud of the
incredible scientific success Philae has delivered.
 Surface as hard as ice unlike expected
Analysis of the data returned indicates that MUPUS did not penetrate much
into the subsurface, which rather than being fluffy as expected is apparently
as hard as ice, and that drill samples were not delivered to COSAC.
Communication loss

20. Potential future reawakening
 Wakes up next August:
Philae appears to have lost all communication capability, but it is possible that
by August 2015, when the comet has moved much closer to the sun in its orbit,
the lander's solar panels will receive enough illumination for ESA to reawaken
it.
As the primary battery wound down "the European Space Agency decided to
attempt to tilt the lander's biggest solar panel toward the sun a last-ditch
maneuver that scientists believe may have paid off."
 Solar panels are the source of Energy:
Philae project manager Stephan Ulmanec said a few days of sun on the solar
panels is all it would take to resume collecting data

21. References
http://sci.esa.int/rosetta/

23. Presented by
Sai Chaitanya Banala