Today’s post was contributed by Luke Lucas, a Mars Express spacecraft operations engineer at ESA’s ESOC mission control centre. Read to the bottom for more info and registration for the upcoming Open Data Day, 28 October 2016, at ESOC! Link to live webcast also at foot of this post.
The vacuum of space is a challenging thermal environment. The illuminated side of an object may reach more than 250°C while the non-illuminated side may be less than -150°C.
Without careful consideration such temperature differences could cause parts of the spacecraft to break, twist or fail to function.
For example: the temperature difference between the front and back of the arrays may be hundreds of degrees and when the arrays go from the shadow of an eclipse, sudden and dramatic changes in temperature occur, which can lead to expansion, contraction, torsion and twisting. Selection of correct materials and good structural design are essential.
Mars Express eclipse Credit: ESA
Maintaining an optimal thermal environment is the task of the craft’s thermal subsystem. The thermal subsystem includes electrical heaters where needed to keep the spacecraft warm (e.g. to prevent fuel lines from freezing) and passive radiators to keep other units cool. In this way Mars Express can perform scientific observations.
Cooling of some units to prevent overheating can be achieved by the clever siting of radiators. By placing radiators where they will always be facing deep space, passive cooling occurs.
The use of multi-layer insulating blankets around the spacecraft promotes a stable thermal environment and minimises the loss of heat to space.
Electrical heaters are used to heat Mars Express and maintain units, structures and instruments within their safe, warm operating range, with more than 200 thermistors continually measuring the temperature at various points around the spacecraft. By monitoring the measured temperatures, the heaters are turned on or off as needed.
As well as keeping MEX warm, it is important to know how much power is needed to achieve this. Power is supplied by either the solar arrays (when exposed to sunlight) by the batteries during an eclipse.
Power produced by either the solar arrays or batteries is used for platform operations, thermal operations and whatever remains is available for science. The energy provided by the batteries during an eclipse is finite, so knowing how much power is needed for the thermal subsystems means mission controllers can know how much power is available for science. Knowing accurately how much power is needed by the thermal subsystem means we can really maximise science observations.
So how much power does the thermal subsystem need to keep MEX warm?
Well it depends how cold the spacecraft is. And that, in turn, depends on many factors. The largest factors include:
Mars orbit Credit: ESA
How far away is MEX from the Sun? The Sun emits solar flux, measured in W/m2, (power per square meter received) and the further away from the Sun, the less flux received – and so the cooler is Mars Express
What is the solar aspect angle? This is the angle of the spacecraft with respect to the Sun? Where is the Sun is shining on MEX? On the top (+Z face), the bottom (-Z face) or the +X face, and at what angle to that face? This will affect the craft’s temperature.
How far is MEX from the surface of Mars? The albedo is the amount of energy reflected off the planet. ‘Mars shine’ refers to the amount of energy being reflected by the planet and can affect MEX’s thermal condition.
Mars Express orbit Credit: ESA
How far away is Mars from the Sun? This affects the Mars albedo, which in turn affects MEX.
Is there an eclipse happening? As seen above, during eclipse, MEX is in Mars’ shadow, receiving no illumination from the Sun, and this can cause a dramatic cool down.
What operations are on going? Certain operations, such as using the transmitter to communicate with Earth, warm up certain sections of the spacecraft.
Here are two thermally representative images of the -Y face, one seen during a communication pass and one when no communications were happening.
In a communication pass with temperatures up to 16°C
Mars Express -Y face, during a communication pass with a ground station Credit: ESA
When not communicating with Earth and temperatures as low as -12°C
Mars Express -Y face, not during a communication pass with a ground station Credit: ESA
That is to say, that the thermal power required changes continuously as the craft orbits Mars and as Mars orbits the Sun; no two days are the same. Predicting the thermal power required is a puzzle of many parts. But it is a very important matter, because we want to perform as much science as possible.
We have a model we use to predict the power required, but wondered if anyone could derive something better.
Our engineering approach is to look at the factors involved and create an equation. But it is always good to look at any puzzle from more than one view. So we asked you, the public to look at this, as the Mars Express Power Challenge.
And – Wow! – we were thrilled by the responses we received, the predictive models that were built and the amount of information shared among this wonderful community of data scientists, researchers, and space fans!
The challenge is now over and the winners will present their solution on 28 October 2016, at ESA’s ESOC mission control centre, Darmstadt, Germany. On this day, the Centre will host an ‘open data day’ for the candidates – and anyone interested is welcome to attend!
This will be an exciting, inspiring day, full of great ideas and exchanges!
A few tickets for the open data day are still available here via EventBrite.
Watch live 28 October, 10:00-12:00 and 14:00-16:30 CEST
The news is out: our little VMC webcam on board Mars Express has achieved adulthood, of sorts! In a web article on 25 May, we announced that the VMC camera is being adopted as a professional science instrument.
Mars seen in May 2016 in three different views. Full details via http://www.esa.int/marstriptych2016 Credit: D. O’Donnell – ESA/Mars Express/VMC CC BY-SA 3.0 IGO – ESA/NASA/Hubble
The article reads, in part:
This spring, ESA began working with the Planetary Sciences Group of the University of the Basque Country, Spain, for an initial two years to develop software and conduct studies of images, effectively promoting the humble camera to the level of professional science instrument.
“The analysis will help us understand the global martian context of data acquired from other instruments, provide data on clouds, dust and atmospheric structures and enable surface features to be accurately characterised, for example, by tracking variations in the Mars polar ice cap,” says Agustín Sánchez-Lavega, heading the group.
ESA’s Mars Express Project Scientist Dmitri Titov is delighted that the camera is opening up a new range of investigations at Mars: “Cloud tracking and dust storm monitoring, for example, are significant topics in the planetary community, and it will allow us to extend Mars Express science ‘into the atmosphere’, filling a gap in the spacecraft’s science portfolio.
The good news is that the transition to a science instrument won’t interfere with the ongoing delivery of VMC images for immediate public viewing and for continued use in outreach, education and citizen science. You remain more than welcome (highly encouraged, in fact!) to access the image sets and use them for your own analysis, processing and sharing (details on CC licensing here).
Working on VMC outreach, education and PR has been one of the most interesting and satisfying projects I’ve been involved with here at ESOC in recent years. I have thoroughly enjoyed being in touch with, and working with, a lot of enthusiastic folks – some within ESA, many external – all of whom have been motivated by the love of science, interest in Mars, support for education and working with an active community.
While I thoroughly enjoyed seeing (and sharing) the many VMC submissions that people on several continents sent it over the years, the most enjoyable activity for me was definitely the 2015 VMC Imaging Campaign aimed at schools, astronomy clubs, science centres and other youth groups.
The level of participation was fabulous (25 groups from the US and Europe) and the resulting work was really well done. It was a genuine pleasure to work with the MEX flight control team here to host a series of Google Hangouts, issue the challenge, receive the imaging requests and then actually conduct the dedicated observations. This might have been the first-ever allocation of multiple orbits of an interplanetary craft to schools and young folks! And it was also a pleasure to see that some groups chose to submit artistic work based on the resulting images, in addition to those who sent in more traditional science projects.
It was also a pleasure working with pro-, semi-pro- and amateur (but v. enthusiastic) planetary science nuts located all over the place!
One of the most active supporters of VMC since the beginning has been Emily Lakdawalla – herself a planetary scientist – who blogs over at the Planetary Society. Emily has done an excellent job over many years highlighting numerous ESA missions, and she was a keen ‘early adopter’ when the VMC images first became available in 2007/08. She promoted and shared VMC images, and designed and hosted online tutorials to help those interested in working with the images learn some of the techniques, and she inspired many others to get involved.
I asked Emily for a few comments, and she sent in this:
The VMC demonstrates the power of a simple camera for exciting the public about the adventure of space exploration. Its images are not large but they are the only ones arriving from any Mars spacecraft that show us Mars as a round planet in all its changing phases and seasons – a view out the porthole of an interplanetary ship. I’d like to see simple, small, wide-angle cameras on all spacecraft to provide context to tell the story of robotic space exploration.
It’s appropriate, however, to take this opportunity to thank everyone who has contributed to VMC since its recommissioning in 2007. People have contributed time, software, knowledge, support to outreach activities, organisational efforts and enthusiasm – and so much more – helping make the VMC outreach effort a real success!
To everyone here, in alphabetical order, a huge thanks!
If I inadvertently left someone’s name off the thanks list, DO let me know!!!!
Last but by no means least, I’d like to thank everyone who has ever downloaded, tinkered with, mashed up, colour-processed, artistically rendered, analysed, processed, shared or in any other way had total fun messing with VMC images. You guys are an inspiring community and it has been your enthusiasm that has made the VMC project a success.
If you’re looking for a nice, historical overview of VMC activities with many updates from the folks who did a lot of the work, there’s no better place than the VMC thread over at UnmannedSpaceFlight.
PS: As Emily pointed out in a separate email, a couple of our VMC community members have since gone on to great things: Both Mike Malaska and Bill Dunford have been absorbed by NASA/JPL!
Update from ESA’s Mars Express project scientist Dmitri Titov on the recent Phobos flyby results.
Unfortunately, HRSC imaging didn’t work due to a transient issue with the onboard memory, which meant that no data were saved. This happens from time to time on our 12-year-old spacecraft and unfortunately this time it occurred during a flyby.
The good (excellent!) news is that other instruments did acquire data, particularly ASPERA, the Analyzer of Space Plasma and Energetic Atoms, which studied interactions between the solar wind and Phobos. It will take the instrument team some time to analyse and process their results, but the initial report is that all went very well.
The MARSIS radar (the Subsurface Sounding Radar/Altimeter) also operated during flyby. Although data are still being processed, it was possible to ascertain that Phobos was detected both in subsurface sounding mode and through ionosphere sounding.
Two more close encounters with Phobos will occur in 2016. On 4 July, Mars Express will approach Phobos at ~350 km, and on 16 November the spacecraft will flyby as close as 127 km. Both flybys will be used to continue the programme of moon investigations.
Mars Express continues exploring the Red Planet – soon in the company of ExoMars 2016 Trace Gas Orbiter!
We’ll update you here in the blog when we have news.
Inputs from today’s blog post were provided by Thomas Duxbury, an interdisciplinary scientist on MEX for the Mars moons and Mars geodesy/cartography (and also a co-investigator on the HRSC scene team), Dmitri Titov, ESA’s Mars Express project scientist, and Simon Wood, from the MEX mission operations team at ESOC, ESA’s European Space Operations Centre, Darmstadt, Germany.
On Thursday, 14 January, ESA’s Mars Express spacecraft will make an unusually close flyby of the largest Martian moon, Phobos, passing the surface at just 53 km at closet approach at 16:00:21 UTC (17:00 CET) on orbit 15260.
The event will mark the spacecraft’s closest flyby of the moon in 2016, and, as a point of comparison, most of the other almost-60 Phobos flybys this year will occur between several hundred up to almost 2000 km. So it’s a real skimmer!
Predicted view from MEX for the 14 Jan 2016 Phobos flyby. The centre image is the predicted perspective view of Phobos at closest approach. This shows the view along Phobos’ shorter axes and it appears smaller than the other two images, which show the view along Phobos’ longest axis. Credit: T. Duxbury
The flyby will enable Mars Express instruments, especially the HRSC – the High Resolution Stereo Camera – to see points of the moon’s surface that have not previously been observed from such a close range.
“This flyby will provide very good viewing, within 1,000 km, of an area previously not seen well,” Dmitri Titov, ESA’s Mars Express project scientist. “HRSC will be taking images; the MARSIS radar and the ASPERA-3 particle instrument will operate as well to sound the subsurface and plasma environment of the moon.”
+ marks the spot
The “+” in the predicted images (see above) indicates a possible landing site for the future Russian Phobos Grunt sample return mission.
“This flyby is important as it will allow us to finally view this area on Phobos that has yet to be seen at high resolution and excellent lighting,” says Thomas Duxbury, professor in planetary science at George Mason University, USA.
In the past, Mars Express has made closer flybys, but not by much. On 29 December 2013, Mars Express flew by at just 45 km, close enough that the moon’s gravity pulled the spacecraft slightly off its course, enabling new estimates of the Phobos mass and density.
Phobos as seen by the HRSC nadir channel during Mars Express Orbit 7926 in 2010. Credit: ESA/DLR/FU Berlin (G. Neukum)
The flyby is an operational challenge as well as a scientific opportunity, as the positions of the moon and Mars Express must be known very, very precisely in order to safely make the ‘skim-by’.
Commands on board
Commands to trigger the instruments’ observations were uploaded Thursday, 7 January, following last-minute optimisation of the expected position of Phobos relative to the spacecraft provided by the flight dynamics team at ESOC , Darmstadt.
“This is needed due to the high level of precision required to target Phobos with the instruments at such a close distance,” says Mars Express Spacecraft Operations Engineer Simon Wood.
“The activity will then take place fully automated and without intervention by the operations team at ESOC, who will be closely monitoring the flyby.”
Flybys such as this help generate evidence to understand how the moon was formed.
The mass of Phobos is estimated as 1.0603 x 10^16 kg (uncertainty less than 0.5 %) and the density is 1862 kg/m3 (uncertainty less than 2%). For comparison, the density of Mars is about 3930 kg/m3, and Earth has a density of around 5520 kg/m3.
The low density of Phobos is consistent with the moon having a high porosity with an uneven mass distribution; in other words, it is essentially a rubble pile with large empty spaces between the rocky blocks that make up the moon’s interior.
This favours the formation scenario in which Phobos was born in orbit around Mars from a disc of debris and is not a captured asteroid – one of the other leading theories for how Phobos and its sibling Deimos came into existence.
Mars Express in orbit around Mars. Credit: ESA/AOES Medialab
The debris disc could have resulted from a large impact on the surface of Mars, or perhaps Phobos (and maybe Deimos) formed from left-over debris from the formation of Mars itself.
Data from such flybys will also prove valuable in planning future robotic or even human missions to land on the moon, and ideal location from which to observe Mars.
It is expected that the initial results from this flyby will be available in the coming weeks.
Get ready to do a lot of scrolling! This is our biggest, baddest blog post ever! #VMCSchools
We’re starting to receive projects from the schools, youth groups and clubs that are taking part in our VMC Imaging Campaign, and the results are simply superb!
This blog post will present the ones we’ve received so far, and we’ll update you in future posts once we get the rest (several participants asked for extensions past the 31 July deadline until September, so it will still be a few weeks – but that’s fine when the quality is this good!).
To recap: In March/April, VMC imaging target proposals were submitted by 25 schools, youth groups and clubs in 12 countries. After extensive analysis, the Mars Express team at ESOC confirmed 22 were doable, given spacecraft and priority science constraints; later, the remaining three participates agreed to take over alternate targets so, in fact, all 25 received image sets. Imaging took place during several dedicated orbits 25/26 May, and we distributed image sets via email the first week in June.
Here’s a little teaser animation developed by the MEX team using most of the 1000+ images acquired as part of the VMC Schools campaign, mashed up to show a full orbit:
Since then, participating groups have been working on analysis of their images, and on educational projects that make use of the images in imaginative, scientific and/or artistic ways (this is a STEAM activity, after all!). And the results are well worth the wait!
Here’s the first impression sent in from the MEX team at ESOC, courtesy Mars Express Spacecraft Operations Engineer Andy Johnstone:
You’ve all achieved what we wanted to accomplish with this project by taking our fairly basic VMC images and doing some really cool things with them! Some of your efforts in image processing have been spectacular and deserve to be published in an astronomy magazine! Your artistry has been amazing and helped brighten up our control room, while the stories, videos and imaginings of visits to the Red Planet have been awesome.
The main thing that’s stood out to us is the passion and enthusiasm that you’ve all shown. That has really made us proud and we’re very glad that this opportunity (conjunction season!) to get so many VMC images came up. We’re planning to have another webcast in September, once the final two projects are in, to go through each of your projects and give you all some feedback.
Thank you all for the effort you’ve put in and we hope that if we manage to do anything similar in the future that you’ll all take part again.
Herewith, we are tremendously delighted (and I dare say just a little proud!) to present (in alphabetical order) the first sets of results and projects from ESA’s VMC Imaging Campaign.
AIM: The chosen region of Mars (Cavi Angusti, a latin name as almost all the geological Mars structures) is located in the south polar region of the Red planet, and is characterized by vast and deep valleys where the thin atmosphere of Mars can produce fogs or mists with daily development. The Mars Express spacecraft passed several times over Cavi Angusti at a distance of about 3000 km, at different times of Martian days, thus allowing us to study the area with a detail of a few kilometres, enough to reveal any cloud formations.
AIM: We would like also to reflect, using the images facilitated by ESA, on the challenges that exploring our dear red planet pose, and on how they can be overcome so that men can get to Mars.
We have used your Mars images about Aeolis Mons in our “space and robotic project” with our children in CODEC. Please, find our latest video “Arriving Mars 2020“, performing the whole Mars missions! And with this CURIOSITY LAB FINAL VIDEO we would like to complete our project with ESA. THANK YOU and ESA so much for all this fantastic images!
AIM: To investigate the conclusion that water was present on Mars looking at surface features such as hematite. Investigate extremophiles present on Earth that may have been present on Mars both in the watery past, and present dry conditions. Come to conclusions about what bio signatures may be present to provide evidence of former or current life. Draw and make artistic representations of life on Mars. Write a poem about life on Mars.
HTBLA Kaindorf, Kaindorf an der Sulm, Austria
Target: Martian Northpole
AIM: Image the Northpole, because we want to find the best landing site for a manned mission. In winter Planum Boreum’s permanent ice cap consisting mainly of water ice and carbondioxid reaches its maximum. So we can find ground without ice to land on, but has water nearby.
AIM: This is interesting because: the Valles Marineris rift system is one of the larger canyons of the Solar System and stretches for nearly a quarter of the planet’s circumference. It has been recently suggested that Valles Marineris is a large tectonic “crack” in the Martian crust. Most researchers agree that this formed as the crust thickened in the That is region to the west, and was subsequently widened by erosion. However, near the eastern flanks of the rift, there appear to be some channels that may have been formed by water or carbon dioxide. The Valles Marineris canyon system is is such a great example of the planet’s tectonic activity and place of geological processes occurrence. In addition, it is possible that in these canyons once flowed water and this could be a friendly place for the emergence and development of life on Mars. Project PPTProject videoProject images in Flickr
IES Alpujarra, Spain
Target: Olympus Mons or whichever frustum-like mountain whose dimensions are well known and easily available
AIM: Kids will firstly work out the picture scale using data available on the Internet and the picture itself. Secondly, they’ll calculate some distances in a straight line and the dimensions and areas of some shapes that may be found on the picture. Thirdly, we’ll try to determine some slopes on the picture to work out an average. Finally, we’ll calculate the approximate area and volume of Mount Olympus thinking of it as a frustum. The results will be presented in English.
Aim: Convert picture to a 3D scaled model and present it to the Science lab or make a puzzle with the picture or make posters that we could place in a local park to teach the general public about the awesomeness of Mars and ESA.
RESULTS TBC: The club jury will view the works of art from the participating schools and select the most striking piece. The award to the best work of art will take place at a public exhibition. The school being awarded first place will be presented with a new telescope for educational use. Thereafter there will be a presentation on the subject of the VMC Imaging Campaign, Olympus Mons and volcanoes on Mars and on Earth (in particular in the Siebengebirge region).
AIM: Our project is called “Picture can say more than a thousand words.” Our aim is to see what are the thousand words we can say about the picture in order to discuss with the children the ways in which we can study other planets in comparison to our own. We would like to use the image to study Martian landscape in detail with the children also with the help of geologists from the University of Tartu Natural History Museum. In addition to geology, we would also like to use the materials as part of the Struve Arc celebrations talking about mapping Earth and Mars. After we have discussed the features seen in the picture, the children will choose the thousand words to be featured on a poster with the picture. This poster will be shown in our museum for the public and we will introduce this also at a large festival taking place in July festival that also has a science section. We already have a programme for schools where we compare the atmospheres of Earth, Mars, Venus and Titan to each other and discuss why we should appreciate our environment.
Poster display by Children’s Club Reegulus at Science Festival
We printed out a number of images and posted them on a whiteboard. Then we began adding words and questions to the whiteboard: what we saw, what we knew and what else we needed to find out. We visited the University of Tartu Natural History Museum to find out about the geology of Mars. After the visit, we added more words, statements and questions to our board. During the final meeting we tried to answer as much questions as possible with the aid of literature and internet and decided on the content of the poster. The poster was finished for a science festival we had in Tartu in July 2015 and the visitors of the festival were able to read it. We also filmed the whole process but unfortunately were not able to secure everyone’s permission to publish this. Perhaps we will do a trailer version later.
The poster gives an overview of Mars that is based mostly on what we saw from the images and the questions that came to our mind while looking at the pictures. The children were most fascinated about the volcanoes, the possibility of life on Mars and, of course, when will we land a human on Mars.
Thank you to everyone who replied to the Doodle poll!
Friday, 22 May, 15:00GMT – 16:30 GMT appears to be the best time slot for the most VMC School campaign participants, so let’s go with that. Go ahead and block that slot in your calendars (as will the MEX team). We’ll post details here in the blog later this week on how to join the #ESAHangout and how to post questions.
Mars Express Spacecraft Operations Engineer Simon Wood adds that, by Friday at 15:00GMT, the command stack that will trigger the VMC observations during ‘your’ three orbits next week should already be on board Mars Express!
The imaging plan with the overall target list for the VMC Schools Campaign is complete!
The MEX team have done a great job reconciling the proposed targets with all the conflicting requirements of the spacecraft, the mandated technical testing that MEX must do, the communication slots, pointing restrictions, etc.
Before you scroll down to the list below, please note several points:
For targets in the northern hemisphere and for equatorial targets (e.g. Tharisis, Valles Marineris, etc.), we will conduct imaging at (mostly) 8000-10 000km altitude.
For targets in the southern polar regions (Cavi Angusti, Phillips crater) we will be able to acquire images from much lower, at about 2000 km.
Irrespective of height, the proposals in green are the ones we believe we can do and get optimum results.
The ones in yellow are possible, but the VMC cannot be pointed directly at them and so the images won’t be centred on the target. While this is not ideal, it’s still pretty good. The green and yellow targets will be programmed into the Mars Express mission plan for the last week in May.
There are three requested observation targets that are, after a great deal of analysis, highly problematic or impossible.
North Pole: For the two observations proposed for imaging the North Pole, we will only see that area when it is about 90% in shadow, so you really wouldn’t see much. As an alternative – and if the proposers (HTBLA Kaindorf, Austria, and Aspiration Creation, USA, can accept) – we will be going over the South Pole under pretty good illumination conditions, and you could get images of that area. Just let us know!
Phobos: Imaging of Phobos (requested by School for Tomorrow, USA) will just not be possible – on the two occasions when Phobos crosses the disk of Mars (and so would be visible), we have an unavoidably higher-priority radio science pass.
The MEX team are now preparing a final mission plan, and we will have an animation and further details for you early next week.
We would also like to schedule a Google+ Hangout on 20, 21 or 22 May to provide interactive answers to as many of the teams as possible. We’ve set up a Doodle poll to determine which date/time is best for the most. PLEASE COMPLETE THE DOODLE HERE to let us know.
Today’s blog post announces the list of proposals that have met the minimum requirements for consideration as VMC imaging targets.
As of 12:00CET today, the open period for VMC Imaging Campaign proposals is closed.
We are incredibly delighted with all the proposals (44 were submitted!), each of which demonstrated imagination and a real enthusiasm for Mars. Thank you to everyone who took the time to submit.
Of these 44, 25 have met the minimum requirements for consideration. Congratulations to those who made the grade! (The full list is at the bottom of this post.)
Making the grade
19 proposals have been rejected, as they failed to meet the minimum requirements, e.g., were not submitted by a group, or were submitted from someone from an ineligible country. We’ve already emailed some of those proposers to tell the news, but this blog post is the ‘official’ announcement: If your proposal is not in the listing below, then you have been rejected as failing to meet the minimum requirements.
Of the remaining 25 valid proposals, that is, the ones in the list below, we intend to try and accommodate as many as possible, but some may yet have to be dropped. This is not because of your efforts, but instead the decision will come down simply to us having a strictly limited observation period and various restrictions relating to spacecraft safety (see our earlier posts: Why conjunction frees up VMC time and VMC Imaging Campaign).
The next step for the Mars Express team is to assess the proposals that are considered to be the most promising (in terms of requested observation target and proposed group project) and work out how many of these observations we will be able to carry out.
How it’s done downtown
This is precisely what professional scientists face when requesting an observation from any spacecraft!
They submit their requests and the mission planners, flight dynamics teams and flight control teams try to carry out as many of these as possible.
As well as checking if a target is in view and safe to observe, there are other factors that have to be taken into account mostly to do with our ‘budgets’. Now by budget we don’t necessarily mean money – but the analogy is the same – you can only spend what is available. We have many budgets, but the main two in this case are the power budget and the data link budget.
To briefly explain these:
Power Budget – as Mars in in a more elliptical orbit than Earth, its distance from the Sun varies significantly over the course of a Martian year (and, thus, so does that of Mars Express), meaning that our solar arrays generate less power and so less is available to supply the instruments at certain time.Also, reduced sunlight makes the spacecraft colder, meaning more power has to be supplied to the heaters, further reducing what is left. We also have eclipse seasons, where the spacecraft passes through the shadow of Mars. During these periods, MEX has to rely on batteries and then recharge them once it orbits back into sunlight. This further reduces the remaining margin.
Link Budget – For communication purposes, we often talk about the distance between Mars and Earth in ‘one-way light time’. This is the amount of time our radio signals take to travel from Earth to Mars at the speed of light.As both planets circle the Sun at different rates, this can vary from about 5 to over 21 minutes. So how does this affect science? To use an analogy, if you stand close to someone, you can speak quite quickly and be understood — but if you are at opposite ends of the street, you’ll have to shout slowly to get your message across.It’s similar for us; at the farthest point from Earth, the MEX data rates can be 10x lower (than when nearest), meaning we either need 10x as much time to communicate with Earth, or produce only 1/10th of the science (or strike a balance in between).
Striking balances between the various budgets is a big part of what our mission planners have to do and this observation campaign is no different. We’ll do our best but won’t be able to confirm anything for a few more weeks.
Accepted for planning consideration
Here’s the list of teams that we are going to advance to the next planning stage. Note that some of you have chosen similar targets, or observations that may be combined, which does make things easier from our side. Listing is in no particular order.
HTBLA Kaindorf, Kaindorf an der Sulm
Sterrenwacht de Polderster, Assende
Phillips Crater (South Pole)
Children’s Club Reegulus, University of Tartu Museum, Old Observatory
Friedrich-Koenig-Gymnasium (FKG), Würtsburg
Hypanis Vallis or Oxia Planum
State International School Seeheim
Global view of Mars
Sternwarte Siebengebirge, Bad Honnef
Olympus Mons and Tharsis region
Friends of Astronomy Club, Thessaloniki
Associazione Astronomica Antares, Foligno
Cosmoscuola, INAF Astronomical Observatory of Rome
Riga State Gymnasium No. 1
Innovation Centre Mill of Knowledge, Toruń
Lisbon School of Education (ESELx)
Curiosity Laboratory, Asociacion Codec de Madrid
IES Alpujarra, Órgiva
Hathern C of E Primary School, Loughborough
Aspiration Creation, Dunwoody
Mars Without Borders, Los Angeles
Valles Marinaris, Olympus Mons, Meridiani Planum or Schiaparelli
Cub Scout Pack 711 Jupiter Elementary School Florida
Mars in half phase showing good shadows.
Out Of This World Space Program, Mariettta
School for Tomorrow, Rockville
Emma C. Chase Elementary School, Wurtsboro
Noctis Labyrinthus or Kasei Valles
Lower Eastside Girls Club of New York
Borinquen Academy of Fine Arts
(project does not require specific target)
Well done to all of you for advancing to this stage and we hope to try and squeeze in as many of these observations as we can!
Announcement of accepted proposals
We are aiming to have the final list of accepted proposals ready to announce within approximately 8 May, and ideally even sooner than that. We’ll update you on planning progress in a couple weeks.
Watch this space!
And thanks again to everyone who submitted observation requests.
NASA will host a media teleconference at noon EST on Friday, Nov. 7, to provide initial science observations of comet C/2013 A1 Siding Spring’s close flyby of Mars and the impact on the Martian atmosphere.
NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft, Mars Reconnaissance Orbiter (MRO), and a radar instrument aboard the European Space Agency’s Mars Express spacecraft provided the first close-up studies of the comet that originated from the distant outer reaches of our solar system.
Briefing participants include:
– Jim Green, director, Planetary Science Division, NASA Headquarters, Washington
– Nick Schneider, instrument lead for MAVEN’s Imaging Ultraviolet Spectrograph, University of Colorado, Boulder
– Mehdi Benna, instrument scientist for MAVEN’s Neutral Gas and Ion Mass Spectrometer, NASA Goddard Space Flight Center, Greenbelt. Maryland
– Don Gurnett, lead investigator on the Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument on Mars Express, University of Iowa, Iowa City
– Alan Delamere, co-investigator for MRO’s HiRISE instrument, Delamere Support Services, Boulder, Colorado
For dial-in information, media representatives should e-mail their name, affiliation and telephone number to Dwayne Brown at firstname.lastname@example.org by 17:00 CET Friday.
Visuals will be posted at the start of the event at:
Comet Siding Spring came extraordinarily close to Mars as it whizzed by on 19 October 2014. The celestial body – a mere 500 metres in diameter – passed the Red Planet at a distance of just 137 000 kilometres, where it was observed by several spacecraft in orbit around Mars. The High Resolution Stereo Camera (HRSC), operated by the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) on board ESA’s Mars Express, also acquired a series of images with its SRC channel during Mars Express orbit 13710.
This animation combines multiple images that were acquired by the HRSC camera on board Mars Express during the comet Siding Spring flyby on 19 October 2014. Credit: ESA/DLR/FU Berlin
As it flew by, Siding Spring was travelling at a velocity of around 56 kilometres per second relative to Mars. Images were acquired at 17-second intervals; the spatial resolution is 17 kilometres per pixel. The images show the comet nucleus as well as the surrounding dust and gas cloud (coma).
Comet Siding Spring originates from the Oort Cloud, a comet ‘reservoir’ in the outer reaches of the Solar System. The comet was named after the Australian Observatory at which it was originally discovered back in 2013, and has the scientific designation C/2013 A1. As comets approach the Sun, one or two tails composed of gas and dust or ionised gases form on the side facing away from the Sun. As it whizzed by the planet, Siding Spring’s tail penetrated the Martian atmosphere, where it was analysed by the particle detector ASPERA-3 on board Mars Express, among others.
Scientists hope to use the data acquired, as well as the spectrometer measurements conducted at the same time, to gain an insight into the comet’s composition. It is thought that comets may contain material dating back to the formation of the Solar System.