Rossetta's comet is spinning down

Comet 67P as observed by Rosetta is very gradually spinning down. It takes 12.4 hours to complete one rotation but scientists have observed that this is extending by one second a day, in other words the comet is getting more active. In September last year, it was determined that the rotation period was extending by 33 milliseconds per day. Now withe comet moving closer to the sun and expelling a much larger amount of gas, this spin-down effect is increasing.

As the comet warms up its ice vaporises and throws jets of gas and dust. These gases expelled are acting like thrusters for the comet by slowing it down as said by flight director Andrea Accomazzo, who has been describing how his team has learnt to fly Rosetta around the comet with remarkable precision, at the Royal Aeronautical Society in London this week.

But how do navigators understand the comet's rotation?
By using a system of landmarks on the 67P being able to see and measure its rotation and trajectory, and sending this information to a model that helps plan the trajectory of the satellite.

During December and January, Rosetta was able to move within 30 km of Comet 67P and go into a gravitationally bound orbit. This is no longer possible and Rosetta has retreated. According to the ESA flight director "The aerodynamic effects are getting more and more important. The jets are getting stronger and stronger. To give you an idea, these gases come out of the comet for a few km and are moving at 800 metres per second. We definitely have to take this into account. We are a big spacecraft with 64 square meters of solar panels. We are like a big sail."

However ESA's is currently planning some closer flybys to try and discover Rosetta's lost landing probe, Philae.

The Rendezvous

          The most difficult part in the mission of Rosetta was the rendezvous with the comet being in movement. This action had many complications, as the high velocity of the comet or breaking any piece of the unit on the landing.
          When the unit was reactivated, the thrusters fired for many hours until the velocity was reduced to 25 m/s. From this moment, the drift was increasingly descending and after 90 days the velocity was of 2 m/s.

          Before the arrival, Rosetta had taken pictures of the comet and made calculations to make possible the touchdown, this made possible the success, Rosetta started sending pictures of the 67/P, with very precise information and being able to look for landing sites, there were five possible.
          Eventually, the spacecraft was inserted into orbit around the nucleus at a distance of about 25 km.
          Finally on november 2014 the rendezvous was possible. After it was chosed a suitable landing site , the lander was released from a height of about 1 km, this action took place at walking speed.
          Rosetta will continue sending data to the earth, until this december it will pass close to the Earth, more than 4000 days afther the mission began.

         

Other ESA's missions

Cluster Mission

The Cluster mission is a non-tripulated mission that studies the magnetosphere over the course of an entire solar cycle. The mission is composed of four identical spacecrafts flying in a tetrahedral formation. A replacement for the original Cluster spacecraft which was lost in a launch failure in 1996, was the four Cluster II spacecrafts which were successfully launched in pairs in July and August 200,onboard two rockets. In february 2011, Cluster II celebrated 10 years of successful scientific operations in space. The mission has been extended until December 2016.

Double Star Mission

Double star was a joint Chinese-European mission directed by ESA and the Chinese space agency (CNSA) also with the objective of studying the magnetosphere complementing Cluster. It was proposed in 1997 and the 1st of July of 2001 they signed an agreement on the mission.

The mission consisted of two satellites. They were both designed, developed and launched by the China Space Administration, flying in different orbits around the earth. The ESA built 8 measuring instruments onboard of each satellite, seven of which were instruments meant to be used in the cluster mission.

Envisat (environmental satellite) Mission
Envisat is an inoperative Earth-observing satellite still in orbit. It was launched on March 1, 2002 aboard an Ariane 5. It is at an altitude of 790 km being in a Sun synchronous polar orbit. It orbits the earth in about 101 minutes with a repeat cycle of 35 days. After loosing contact with the satellite on April 8, 2012, ESA formally announced the end of Envisat's mission on the 9th of May 2012. Envisat is the largest civilian Earth observation satellite put into space.

MMS spacecraft launched Thursday night

       Three nights ago, the Magnetospheric Multiscale (MMS) was lauched. Not just another spacecraft: it will lead to the Earth magnetic field's full understanding.

       MMS consists of four identical spacecraft that will orbit around Earth through the dynamic magnetic system surrounding our planet to study a little-understood phenomenon called magnetic reconnection.

This mission will provide the first three-dimensional view of magnetic reconnection in the Earth to the Sun, a process that will help to understand how are the magnetic fields in the universe connected and disconnected. Scientists hope to obtain data of the structure and dynamics of the energy exchange magnetic fields when found, at which an explosive release of energy is produced.

       The four spacecraft, equipped with high-precision sensors, simultaneously fly in formation, at a distance of about 10 km from each other, so that the combination of this data allows to have a three-dimensional view.

       The MMS mission will use the Earth's magnetosphere as a laboratory to study magnetic reconnection addition, two other fundamental processes such as acceleration of energetic particles and turbulence.

       The launch was the 53rd for the Atlas V and marked the completion of about six years of rocket selection, manufacturing and integration ahead of the launch preparation for the MMS and NASA's Launch Services Program teams along with United Launch Alliance.

The MMS a day before its launch, which took place through 

an Atlas V 421 rocket from the SLC-41 ramp of Cape Canaveral Air Base.

Is Philae alive?

    For the first time since Philae fell in silent in the last November, Rosetta is trying to make contact with it.

    Philae fell sleep two days after reaching the comet 67P, the cause of this was that Philae ended in a cliff or boulder wall that don't aloud Philae to take as solar energy as it will be needed. But this issue will probably get solved when 67P get nearer to the sun so more sunlight will reach it and because of that more solar energy will receive Philae. Due to this lack of energy Philae turn off all its system except one that prevent that the electrical circuits of Philae get freeze, but Philae is programmed to turn on its system as it receive more solar energy, starting with the system that aloud us to communicate with Philae.

    As I said before the ESA is now trying to contact Philae, they are sending to it some orders to get active if it have enough energy, but by this moment the ESA expect that Philae will be receiving data but it will  not have enough energy to answer the message. However Rosetta will keep trying to make contact until the 20 of March, and by that day Philae don't have make any contact, Rostta will stop
and will keep trying it in March.

University of Tokyo's CanSat in 2002

As the Titech (Tokyo Institute of Technology) CanSat in 1999, the University of Tokyo planned and designed their own CanSat in 2001 also as a Japan-U.S. joint venture to make satellites for educational purpose. Their CanSats were designed to deploy a thin flexible membrane using centrifugal force. As it happened in previous editions, the satellites were launched in a rocket called AIRLISS (A Rocket Launch for International Student Satellite). Three different CanSats were built and launched at the Black Rock desert, in Nevada. Each one had a specific mission:

        - CanSat#001 was a prototype of the orbital model of Gekkabijin (a nano satellite which was being designed at that moment by the laboratory of the University). Its missions included rotating CanSats using a reaction wheel, charging secondary batteries by solar cells, estimating attitude using a gyro and solar cells, performing communication and sending telemetry among other things.

        - CanSat#002's main purpose was to test electronics and six sensors. Besides, its structure was made of a usual juice can to reduce its weight.

        - CanSat#003 was equipped with a CCD camera and a high power transmitter which was able to send the taken pictures during the flight to the ground station.

There were some failures in parts such as the antenna, but as an educational project it was a success thanks to the learnt skills by the students.

Rosetta lost contact with Philae

        The sounding line Rosetta of the European Spacial Agency stills without contact with Philae.

        This Thursday, after a few hours, the receptor, which made history months ago landing in a comet and was expected to contact with the unit, was turned on.

        According to the ESA, the operation was performed at 1.00 a.m. and it hasn't received any signal of the unit Philae yet. This unit entered in a state of hibernation, just after setting in the comet 67/P, due to a shortage of energy.

        The line won't be opened until the next friday, but a good communication is not expected. It is more probably to receive a signal from Philae on June or July.

        The comet is now only at 300 millions of kilometres from the Sun, so it's worth to try to contact it. Whenever the comet gets closer to Sun, its temparature will increase. Until Philae does not reach -45ºC, it will be impossible to wake up the unit.

        If it achieves this temperature, Philae will be able to charge its batteries and to turn on the receptors every 30 minutes waiting for a signal from Rosetta. The information that they are going to collect from Philae will treat mostly about unit's state.

        They will have difficulties to succeed, but we will see what happens at the end...

Why 67P/ Churyumov-Gerasimenko?

      Rosetta's space mission was to follow the asteroid 67P until the spacecraft and the asteroid rendezvous and carry a scientific study of the asteroid. But what is the point of following this specific asteroid?

      To answer that question we must consider some of the most important factors which made the ESA choose this asteroid.

      The main point that was observed was that the asteroids must be near enough so the spacecraft was able to rendezvous with them as soon as posible. At the beginning, 67P was not selected as the target, but, due to some problems with the Ariane 5 (the carrier rocket of Rosetta) the launch was postposed to the next year, so it was impossible for Rosetta to reach 46P/ Wirtanen at time. Due to this, 67P was designated as the main target.

This decision was made because 67P was know for having water vapor, so the objective of the space mission Rosetta was stablished as analyzing that water vapor in order to aloud us to study the difference of "extraterrestrial" water and earth´s water.

Comet 67P on 7 August

Philae

Philae is an ESA lander that accompanied the Rosseta spacecraft on its mission until it landed on comet 67P more than 10 years after it launched from The Guiana Space Center in French Guiana. It landed on the 12th of November 2014 achieving the first ever soft landing on a comet nucleus, obtaining the first images of a comet´s nucleus.

The spacecraft is tracked, managed and operated from ESOC space center in Germany. It has been the first spacecraft to be able to make a direct analysis of a comet with several instruments, sending back information to be able to determine the composition of the comet´s surface.

It gets its name after the philae obelisk which was used along the rosseta stone to decipher Egyptian hieroglyphics. As of today Philae remains shut off and in safe mode due to not enough sunlight and disorientation after landing in an unplanned site. Because of the little light it receives it is currently incapable of communicating with its sender Rosseta. Mission controllers at ESOC hope that by August this year it will receive enough energy to power up and reconnect with Rosseta.

Philae's scientific goals focus on " elemental, isotopic, molecular and mineralogical composition  of the cometary material, the characterisation of physical properties of the surface and subsurface material, the large-scale structure and the magnetic and plasma environment of the nucleus".

The primary battery was designed to be able to power Philae's instruments fore more or less 60 hours. ESA expected that a secondary battery would be at least partially filled by the numerous solar panels attached to the outside layer of the spacecraft, but the limited sunlight (90 minutes per a 12.4-hour comet day) at the unfortunate, unplanned landing site is inadequate to capture sunlight, at least in this phase of the comet´s orbit. On the morning of the 14th of November 2014 the battery was supposed to last until the end of the day. In order to use as least battery as possible the first data obtained was from instruments whose measurement procedures did not require mechanical movement, being able to get 80% of the initially planned scientific observations. During the "evening session" of that day Philae was raised 4 cm (1.6 inches)and rotated its body 35 degrees to a more favourable position for the largest solar panel of all, to try and capture as most sunlight as possible in the future. This operation of lift up and rotation used up quite a lot of battery, forcing a shut down of all instruments . Contact was lost on 15th of November at 00:36 UTC. The German Aerospace Center's spacecraft manager 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 success Philae has delivered.

Titech CanSat project in 1999

Prof. Twiggs, from Stanford University proposed the CanSat project at 1998 University Space Systems Symposium in Hawaii. The project was a collaborative effort between U.S. and Japanese universities to develop can's size satellites (CanSat).



Titech (Tokyo Institute of Technology) designed and built some prototypes, exactly four. Their CanSats were launched on an amateur rocket called ARLISS (A Rocket Launched International Student Satellites) on 1999. The launch place was located at the state of Nevada, in the Black Rock desert. Those satellites reached a height of 3657m approximately, which means a low orbit flight. Each CanSat had a specific mission:
     
        - CanSat Type1, called "Spider". Its mission consisted of testing a small reel system for space tether applications

        - CanSat Type2, named "TeS". Its objective was to show that the tethered satellite was able to go up and down along the tether thanks to designed small roll mechanisms.

        - CanSat Type3 whose name was "[etc]". Its was described as a communications and electronic devices test satellite. It carried seven sensors (3 gyros, 2 accelerometer sensors, a temperature sensor and a pressure sensor).

        - CanSat Type4 named "SabSat". Contrary to the rest of the satellites, this one's size was 150ml instead of the usual 350ml. Its mission, transmitting NTSC signal of CCD video in UHF during the descent period.


The launch was conducted on 11th September 1999. Some technical problems happened ("[etc]" and "SabSat" were tethered in the rocket). However, it should be considered as a brilliant project for being pioneer in the CanSat field.
                                                                                                         

How is divided the comet 67P

Rosetta orbits around the comet 67P also called Churyumov-Gerasimenko due to the astronomers Klim Ivanovych Churyumov and Svetlana Ivanova Gerasimenko. This comet have a shape which looks like two spheres, one bigger than the other, and a link between them. The ESA had separated this comet into 19 different regions as is shown in the photo below. This regions where named using the names of different gods of the ancient Egypt, this is because the Rosetta stone most important use was to make us able to understand the hieroglyphs that were used in the times of pharaohs.

Map of comet 67P divided in 19 regions

© European space agency

Rosetta's first selfie

Today the ESA had published some photos that were took in the Valentine's day by Rosetta to the comet 67P. One of them in particular shows Rosetta's own shadow.
This photo is the highest resolution one ver made to this comet and was took while sweeping 6km above comet 67P surface.

The photo was able to happen only because of the sun position (just behind the satellite), in what is called a "zero phase" angle. As a result of this, we could consider that as the first interstellar selfie ever made, if you consider that the shadow is a part of Rosetta and not just a consequence of the satellite obstructing the sun light.

Photo of Rosetta´s shadow took by Rosetta satellite

© European space agency

Why Rosetta?

             The European Space Agency's (ESA) mission of cometary exploration, that is now in orbit is named after The European Space Agency's (ESA) mission of cometary exploration, that is now in orbit is named after the famous 'Rosetta Stone'. This piece of volcanic basalt, which is at the moment in the British Museum in London, was the key to shed light on the civilisation of ancient Egypt. famous 'Rosetta Stone'. This piece of volcanic basalt, which is at the moment in the British Museum in London, was the key to shed light on the civilisation of ancient Egypt.

             This unique stone was discovered in 1799 by french soldiers, as they were going to demolish a wall near the village of Rashid (Rosetta) in Egypt's Nile delta. The inscriptions that were carved on the Stone included hieroglyphics not only of the written language of ancient Egypt but also Greek, which was easily transcripted. 

             The Siege of Alexandria was fought between 17 August and 2 September 1801, during the French   Revolutionary Wars, between French and British forces and was the last Egyptian Campaign. The french soldiers had occupied Alexandria, a major fortified harbour city on the Nile Delta in northern Egypt, since 2 July 1798, and the garrison there surrended on 2 September 1801.After the French surrender , the 762-kilogram stone was handed over to the British.

             By comparing the inscriptions on the stone, historians were able to begin deciphering the mysterious carved figures. Most of the pioneering work was carried out by the English physician and physicist Thomas Young, and the French scholar Jean François Champollion. As a result of their investigation, scholars were at last able to piece together the history of a long-lost culture,  Egypt.

             Just as the Rosetta Stone provided the key to an ancient civilisation, so ESA's Rosetta spacecraft will unlock the mysteries of the oldest building blocks of our Solar System – the comets. As the worthy successor of Champollion and Young, Rosetta will allow scientists to look back 4600 million years to an epoch when no planets existed and only a vast swarm of asteroids and comets surrounded the Sun.

Regional Cansats

Most countries participating in CanSat have to previously undergo a national competition in order to compete internationally.

In Belgium CanSat competition started relatively late in comparison to other countries. A regional competition took place in brussels in 2013 organised by a non-government financed organisation using T-minus engineers. They used the kit they had previously built by them to launch the rockets. Everybody that took part in this competition was aged 17. They formed up to 6 teams and the winner of them all participated in the European CanSat of 2014.

In France it started earlier. It was first established for college students by the french space agency and the famous educational institution of Planète Sciences. In 2014 it was a national campaign that took place in August for a whole week as. It was described as: "a week full of twists during which which young people have been able to implement their project exchange with various clubs and participants present, meeting space professionals, attending launches of experimental rockets and engagement in achieving their first space project.Experimental rockets, mini-rockets, CanSat, stratospheric balloons, and even water rockets are implemented during this intense week by our young enthusiasts. It is also a time of meeting participants to develop his project through viewpoints between the educational dimension, industrial, scientific and international." The competition takes place every summer in Biscarosse, France.

In Germany it is held in Bremen in the month of October, although, up to 10 teams are elected in Germany from a series of secondary schools which calls for proposals open in January and are chosen by February. It is supported and organised by companies, institutes and organisations  specialised in aerospace technology.

Stay tuned for more countries participating in Cansat!!!

First "CanSat" in 1987!

Apparently Terrance L. Thomas and David W. Yoel knew that small sized satellites would play an important role in the future. They called their satellite CANSAT. Their aim was no other than describing a telescience vapor crystal growth experiment launching the small sized satellite into low Earth orbit. The growth would be experimented due to an implemented transparent furnace. Crystalline materials growth needed to be studied because of the limitations that semiconductor devices suffer due to the size and the quality of those materials.

During the same year, NASA decided to study the feasibility of a small and inexpensive aircraft for a low-frequency radio interferometer array. They called it "GAS-Can" satellite. Scientist's goal was to produce high angular resolution images of the entire sky at frequencies from 2 to 20MHz. One of the developmental wed of the GAS canister is the ejection of free flying satellite (CANSATS). Their conclusion was that no fundamental problems were found for building an untraditional and inexpensive spacecraft. Its dimensions were 48.3cm in diameter and 88.9cm in length.

CANSAT and GAS-Can satellite showed us that everyone can investigate, because, apart from being an important breakthrough in terms of small satellites development, it was above all, a way of bringing aerospace science to ordinary people, mainly due to its low cost and short time of preparation that the experiment may need in comparison to the needed with big satellites.