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 update compiled from inputs by several of the Mars Express team at ESOC. Thank you Simon, Andy and our Spacecraft Operations Manager Michel – Ed.
In the weeks since we announced which entries had made it through to the final round, we’ve been busy working out how many of the observations would be possible.
Even before we announced the VMC Schools Campaign, and assuming we might get, say, a handful of submissions, our original plan was to select as many of the requested targets as possible and then command Mars Express to turn and point VMC at each of them as it orbited the planet.
As you know, we ultimately received 25 excellent proposals (thank you!) and so the MEX team have been working hard to revise our strategy to accommodate this large number of requests.
The VMC webcam provides images of Mars having about the same quality as those provided by the ESA/NASA HUbble telescope. Image credit: ESA/Mars Express/VMC/ Humboldt Gymnasium, Vaterstetten
Mars Express was designed for performing steady observations and not rapidly turning to point at different science targets (we call these “pointings”).
And, as a safety feature, Mars Express is programmed to return to Earth-pointing between each science pointing (and it doesn’t slew, or rotate, very fast anyway – only about 10 degrees/min). Even a very short observation can take up to two hours, out of which 45 minutes are required for the move from Earth to the target pointing, and another 45 min to move back . As the spacecraft orbits Mars every seven hours, this restricts us to about three pointings per orbit.
Also, even though science will be turned off during the upcoming conjunction period, we must still allow time for communicating with Earth, which can take up to eight hours at a time. With the antenna and all the instruments rigidly fixed to the body of Mars Express, we cannot use communication periods for conducting observations with VMC. We also have other spacecraft tests that must be conducted in the week of 25-29 May.
All this reduces the number of orbits we have available for the VMC Campaign to four.
We also noticed that quite a few of the requested targets are close to each other. This causes a problem in that if we were to slew the spacecraft to point at any one first, by the time we have done this, then pointed back to Earth and then moved on to the next (nearby) target, it may well have moved out of view.
Together, these constraints mean that we might only observe about five of the proposed targets. Clearly, with so many excellent requests and so few discrete pointings available, we needed to devise Plan B.
When the cosmos hands you lemons, make lemonade
Of course, being Mars Express engineers, if we’re told that something is difficult or impossible, we take that as a personal challenge! We suspected that we could improve on this situation, and started working on ideas for a better plan.
First, note that, at 45 degrees, the field of view of the VMC camera is much larger than that of our main science camera. After a series of simulations, it became clear that by simply pointing VMC straight down and then flying the orbits, many of the requested targets would pass into view of the camera.
This wouldn’t be quite as good as performing individual pointings, but it would still be pretty good and remove the need for the time-consuming slews.
The trouble is, pointing VMC ‘straight down’ is not quite as simple as it may sound. What we actually do is called a ‘spot pointing’ in which Mars Express’ attitude control system aims an instrument at a specific point on Mars (such as Olympus Mons, for example) and then the spacecraft continuously adjusts its orientation to keep the instrument fixed on that spot.
In order to point down continuously, we would in fact need to conduct many of these spot pointings in a row – but then this means many slews and we’d be faced again with the multiple 45-minute slew delays!
That ‘a-ha’ moment
What we need is a single point on (or ‘in’) Mars that is ‘down’ no matter where we are over the surface; as it happens, there is such a point: The very centre of the planet.
The result is that VMC will continuously track the planet itself, keeping it in the camera’s field of view during the entire way around the orbit; by taking pictures at regular intervals we can then capture far more of the requested targets as they pass into view.
Indeed, at least one, or even, with some luck, several of the images thus acquired will be the closest to each of the requested targets. The MEX team at ESOC will download all the images, identify which picture(s) taken at which time(s) match the requested target, and parcel them out accordingly.
While this solution may seem obvious, remember that as the main instruments are only ever pointed at specific targets, this kind of observation was never catered for in the planning and control systems, and so we have had to do some deft programming to ‘fool’ the system (thanks for avoiding the word ‘hacking’ in our public blog posts – Ed.), but just by a little.
We think it’s an elegant solution to a perplexing problem and we think most if not all proposals can be met.
Making space movies
This solution, as hinted at the start of this post, uses the same technique we used for the Mars full orbit movies. The difference is that then, we collected a batch of images (about 600) during a single continuous orbit of seven hours.
This time, we will be performing the pointing in three segments for a total of 28 hours over a three-day period. This allows the best compromise between the requested VMC observations and the required communication periods and subsystem tests that we must do.
Reaction wheel on board Mars Express Credit: ESA
Currently, this plan is in the final stages of checking; our Flight Dynamics team are performing the required detailed calculations on the effects this will have on the spacecraft
For example, we cannot expose certain sides to the Sun for too long, nor can we allow our reaction wheels – the devices which turn the spacecraft to point in the desired direction – to build up too much speed.
The good news is that their analysis is almost complete and we expect the results shortly.
Once we have these, we can then use their output to generate a final simulation of the three-day observation period and can then give a final confirmation of which targets will be observed.
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.
We often refer to VMC as the ‘Mars Webcam’ since the images it takes are comparable in resolution and colour depth to those of a standard home webcam that you would have bought from your local PC store back in 2003 when the spacecraft was launched.
However don’t let the Webcam tag fool you! It’s a serious piece of kit with a very real engineering purpose.
That purpose is to help overcome one of the challenges faced when flying spacecraft: we can’t actually see them.
We overcome this problem by having huge amounts of telemetry data transmitted back to us here on Earth to give us details about what every component on board the spacecraft is doing.
However, this telemetry is in effect just numbers on our computer screens that come from the sensors all over the spacecraft.
For example, if we were to command the solar arrays to turn, we can say that we can ‘see the arrays turning’. What we really mean is that on the mission control system computer screen, we can see that the parameters that correspond to readings from sensors on the solar array drive motors reporting that the voltage going to the motors is changing, and that the power being consumed by the motors is changing. Finally, we can see that the power being generated by the arrays themselves is also changing. The changing numbers on the screen are all we have to go on.
This is a limitation we accept as part of sending things out into space and operating them remotely. It also shows why the telemetry sent back to the mission control centre is so vital to understanding what the spacecraft is actually doing.
However, there are occasions on some missions where an activity considered so critical that telemetry alone is not enough, we need to be able to really see – visually – what is going on so we can be sure it has worked correctly, or if there is a problem, to be able to see what has happened to enable us to try and fix it.
This is where cameras like VMC come in. Indeed, the clue is in the name: VMC = Visual Monitoring Camera.
For Mars Express, the part of our mission that required the use of a camera was the release of the Beagle 2 Lander.
To enable Beagle 2 to reach its desired landing site it was necessary to detach the lander from Mars Express at a very precise time and in a precise speed and direction. So that we could check this, VMC was used to take a number of images during Beagle 2’s departure from Mars Express.
Separation of Beagle 2
These images were then analysed by the flight dynamics team here at ESOC who were able to work out from them that the release had gone perfectly and Beagle 2 was on the correct course for the surface.
Mars Express is not the only ESA spacecraft to be fitted with a monitoring camera.
The 4 Cluster spacecraft were launched in pairs with one spacecraft attached to the other. The top spacecraft in each pair was fitted with a camera.
This was used to monitor the crucial point at which the 2 spacecraft separated from each other. As this happened in low earth orbit the pictures that were very spectacular.
The XMM space telescope also has monitoring cameras installed. they are looking along the spacecraft towards the service module.
They are aimed in this direction as their purpose was to allow the flight control team to check the unfolding of the spacecraft’s solar arrays.
Sentinel 1a which was launched last year has cameras to check the deployment of both the solar panels and its long radar boom. Finally, Whilst not a simple monitoring camera, Rosetta used its main science camera to image the Philae lander as it departed for the surface of 67P.
This was far more than just a good bye image from one spacecraft to another as this was able to show the lander team that Philae’s landing gear had unfolded correctly. — Simon Wood
Spacecraft Operations Engineer, Mars Express
Here is Andy’s presentation file, illustrating the typical resolutions of VMC images
Original post below
As part of the #VMCschools public observation campaign, all registered participants – plus those who are thinking of registering – are invited to join the Mars Express mission control team in an #ESAHangout via Google+.
The video hangout will run about 60-75 minutes, and will include a live tutorial covering:
The Mars Express spacecraft and mission
The Visual Monitoring Camera, the ‘Mars Webcam’ – how it works and what it can see and do
Review of possible observation targets on Mars that you can request
The #VMCschools public observation campaign: what/when/how/who, limited number of slots; what you are expected to do
Andy Johnstone Credit: ESA/J. Mai
Mars Express engineer Andy Johnstone, above in the Main Control Room, will be joined by Simon Wood, also on the MEX team, and ESA Mission Analyst Michael Khan, both pictured below; Daniel Scuka will moderate and host.
Michael Khan Credit: ESA/J. Mai
Simon Wood Credit: dpa
In the second half of the #ESAHangout, we’ll respond to questions from the public, giving priority to any submitted by already-registered participants. Questions may be posted as follows:
You may be wondering why the VMC camera will be free for public imaging requests on 25-28 May – and hence why we can run the VMC Imaging Campaign. Mars Express Spacecraft Operations Engineer Andy Johnstone provided this reply.
The present conjunction period, when the Sun will block the direct line of sight between Mars and Earth, starts on Friday, 28 May, and lasts about five weeks until 1 July; the conjunction point happens on 14 June. As we’ve described before here in the blog, routine science payload observations are carefully planned well in advance.In this case, there is a boundary on the planning period (which are normally 28 days) that ends four days before 28 May, and it was decided by the operations and science planners not to conduct science during only four days.
ExoMars Trace Gas Orbiter at Mars. TGO will be launched in 2016 with Schiaparelli, the entry, descent and landing demonstrator module. It will search for evidence of methane and other atmospheric gases that could be signatures of active biological or geological processes on Mars. TGO will also serve as a communications relay for the rover and surface science platform that will be launched in 2018. Credit: ESA–D. Ducros
So, while this frees up a rare time slot when no science will take place, and while VMC therefore may be used for this valuable public and educational outreach activity, this isn’t the only activity happening during the four days. We are spacecraft engineers, after all, and our goal is always to test, optimise and maximise the performance of our spacecraft.
We are performing other activities in this 4 day period:
Monday-Wednesday: Tests with MELACOM (our UHF radio used to communicate with landers on the surface) as part of preparations for Mars Express to support ExoMars Entry Descent Module (EDM) landing next year.
Tuesday: A test for the Trace Gas Orbiter (TGO) mission, a partnership between ESA and Russia’s Federal Space Agency, Roscosmos. They want to prove that we can perform ground station swaps without bringing down the carrier. We are going to let them use MEX as a test vessel.
Wednesday: Performance tests on our solar arrays and batteries (last done just after the passage of comet Siding Spring in October 2014) and testing of redundant heater lines. We may also perform a special pointing with all instruments OFF in order to get a more accurate model of how much heating comes from the Sun, and how much is from internal components.
Wednesday-Thursday: Loading of the most vital commands to configure the craft for the Solar conjunction period. These relate to our attitude and orbit control system (AOCS). For this conjunction, we will be leaving our X- and S-band transmitters ON throughout as we do not have any power limitations this year.
Thursday: A full performance check of the Transponders (radio transmitter/receivers) in both X- and S-band; this takes advantage of us having some long passes with no science data to be dumped. We can see how they both behave at the same distance on the same station with the same weather.
So, VMC is not the only valuable activities taking place in the run up to the conjunction period. We are using this opportunity to carry out lots of tests and it is likely that we may end up with more. But, with VMC, we are using some spare time in between operational activities to give something back to the public – especially students and teachers – who are some of our strongest supporters!
Information for schools, astronomy clubs, science centres and any other eligible group wishing to take part. Official hashtag: #vmcschools
NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft successfully entered Mars’ orbit at 04:24 CEST on 22 September 2014. This image was acquired by the low-resolution VMC camera on board Mars Express at 14:50 CEST on 20 September, when MAVEN was an estimated 312,000 km from Mars. Credit: ESA/MEX/VMC
Mars is approaching solar conjunction where it will be on the opposite side of the Sun from Earth; this will affect communication with the spacecraft for a period of about five weeks and so science observations have to be stopped.
For this particular Solar conjunction, running for about five weeks between 28 May and 1 July, the Mars Express team will be stopping science four days earlier than usual for operational reasons. Part of this time is to be used to run tests on spacecraft subsystems, but we have an exciting plan with what to do with the remainder! (See details via Why conjunction frees up VMC time?)
How would you like to be a scientist on a Mars mission?
We would like to offer the opportunity for about eight (final number depends on the proposed targets) schools or other youth clubs/organisations to propose observations to be performed with the VMC camera (in principle, almost any large feature on the martian surface can be imaged) and then complete and submit a project report with their results; we’ll publish them here in the MEX blog. (See official announcement plus link to terms, conditions and the registration form here.)
The closing date for proposals is 12:00 CET on 27 March 2015 – which is not far off, so you’ll need to work quickly if you wish to be involved.
So what do you need to know?
First of all, you need to understand a bit about the VMC camera. It is our most basic instrument, being basically a low-resolution webcam that was originally only to be used to record the release of the Beagle 2 lander. Since then, we have used it to take some very impressive images of Mars, its moons and atmosphere as well as other planets. Although lacking the extreme resolution of the professional HRSC camera on board Mars Express, it does allow the entire martian disk to be observed in a single image. Go through our Flickr library to get a good idea of what we can do with it.
The VMC webcam provides images of Mars having about the same quality as those provided by the ESA/NASA HUbble telescope. Image credit: ESA/Mars Express/VMC/ Humboldt Gymnasium, Vaterstetten
In fact, VMC provides images of Mars having about the same resolution and quality as those obtained by the ‘professional’ ESA/NASA Hubble orbiting observatory!
Next, you need to know a bit about the orbit of Mars Express. We don’t expect you to attempt any of the incredible mathematics that our Flight Dynamics team here at ESOC perform on a routine basis, do but you need to understand that Mars Express has a highly elliptical orbit, which – combined with the rotation of Mars – means that not all of the planet’s surface will be visible to the camera during the available observing slots during 25-27 May.
Take a look at the VMC full-orbit animation, derived from Celestia, which is a great way to visualise what VMC can see during 25-27 May.
You will also need to know a bit (but not too much!) about Mars Express. Keep in mind that although we are inviting you to point Mars Express at a target of your choice (the VMC camera is fixed in position, so to point it, we slew the entire craft), we have many rules and restrictions for ensuring the safety of the spacecraft that cannot be violated.
We will take care of this within the MEX flight control team here at ESOC for you, but there are a few obvious things that you need not request, such as pointing toward the Sun or asking for two targets in quick succession (we avoid turning the spacecraft too quickly). Also, as Mars (and hence Mars Express) is almost at its furthest distance from Earth, the amount of data we can return is very limited (which is why the professional instrument payload is being switched off in the first place), and so we will not accept any long observation proposals (this also enables a larger number of short observation slots, giving as many schools or clubs as possible an opportunity to carry out observations).
The Red Planet
Some knowledge of Mars is also important – as we assume that is at what you will be pointing VMC. In principle, you could request to point VMC away from Mars, but, as it is a low-resolution device, we don’t think you’ll see that much (we did get a misty shot of Earth one time!). We will leave this for you to research on your own. There are many sources of information on the Main ESA website, the Internet and in your library that you will want to look in to in order to come up with a good proposal.
Emily Lakdawalla, from the Planetary Society, has posted online a series of excellent tutorials on working with space images, including the VMC. And you can find all archived VMC images for practice via the Mars Webcam blog and Flickr.
... and the fine print
Mars Express is an operational mission, and considerations of spacecraft safety and the primary professional science mission always come first. We may have to amend, change, or cancel the VMC Imaging Campaign at any time, or there may be some other reason why we can’t carry out your requested observation(s). But the slots on 25-27 May are looking good and we will do our best!
Tweet with the hashtag #vmcschools or post a query in the blog
So, what can you propose?
What do you think you can do? Would you like to get a close-up image of a certain feature (Olympus Mons?), or observe the whole of Mars? Are you going to work with raw VMC data or use the processed images? Can you identify certain features or landforms and explain what is going on? What caused them? We aren’t necessarily looking for the cleverest or most innovative observation proposals, but we will select eight (or so) good ones that we can fit together in to our observation window and that provide the best scientific, artistic or educational merit.
So, if you would like to take part in this extremely rare opportunity to briefly ‘take charge’ of a spacecraft around another world, make a plan and submit your proposals. Time is short and we know that there are many enthusiastic people – teachers, students, artists, young amateur astronomers and many more – out there with great ideas. Best of luck and we look forward to hearing from you!
Editor’s note: Thanks to Andy Johnstone & Michel Denis for this post
19 March – #ESAHangout via Google+ – Mars Express mission team will provide a tutorial on the VMC and how its images are planned & acquired
27 March – Deadline for registered groups to submit final proposal (12:00 CET)
8 May – #ESAHangout via Google+ – the Mars Express mission team will announce accepted observation targets
25-27 May – VMC imaging!
28 May (+/-) – VMC images downloaded and delivered to participant groups
End of current academic year or 31 July, which ever comes first – All participant groups must submit project report
We asked Michael Khan, working at ESA’s Mission Analysis Office at ESOC, what he would select as targets for VMC. His comments and some very useful charts are below – Ed.
Potential observation targets
Here are a series of charts that indicate when/where MEX will be in relation to a selection of nine surface features (click for full size). These indicate the ground track, time, the range and the elevation for Mars Express (and hence the VMC) with respect to nine select features.
The ground track of the Mars Express spacecraft from 25 through 27 May. Where the red line is vertical, the spacecraft is passing its closest point to Mars, at around 250 km over the surface. Conversely, where the line is canted, the spacecraft is near the farthest point out on its elliptical orbit. This diagram shows the entire ground track – however, some of the ground track also passes over the Martian night, when the regions directly below are dark. Credit: ESA/M. Khan
The local solar time is the current actual time at a given Mars location. In late May, it just so happens that the orbit is oriented such that most passes occur in the local morning hours, with very few passes (those that occur when the spacecraft is closest to Mars) in the late afternoon. Credit: ESA/M. Khan
For the nine sample locations, the range (distance from the location to Mars Express) is shown for 25-27 May. Ideally, to obtain bright, high-resolution images, the elevation (see http://bit.ly/1MbUteQ) should be high and the range should be low, though this combination may be difficult to obtain. Credit: ESA/M. Khan
For nine sample locations on Mars, the elevation at which the spacecraft passes overhead, 25-27 May, is shown. Only those overflights where the Sun is up at each of the respective locations are taken into account. The higher the elevation, the better the observation conditions. For 90-deg elevation, Mars Express would be directly overhead. Credit: ESA/M. Khan
Two proposals from my side, based on my results:
Eos Chasma on 2015/5/28, around 07:00 UTC at <2000 km range and up to 65 deg elevation. Arguably, pretty!
Elysium Planitia and Elysium Mons on 2015/5/26 around 16:00 at <1200 km range and up to 45 deg elevation, and again on 2015/5/27 at 18:00 UTC at <2000 km range and up to 55 deg elevation. This area is the one where Mars Express saw the ‘frozen sea’ 10 years ago. It is also the landing region of NASA’s Insight Spacecraft in September 2016.
MEX Spacecraft Operations Engineer Simon Wood points to telemetry packets streaming down from Mars Express, indicating that signals were received earlier this afternoon from NASA’s Curiosity on the surface. Test of the contingency relay link using Mars Express is complete!
This update sent in earlier today by ESA’s Simon Wood, one of the engineers working on the Mars Express mission operations team at ESOC.
Today, ESA’s Mars Express orbiter will send telecommands to NASA’s Curiosity rover on the surface of Mars.
This self-portrait of NASA’s Curiosity Mars rover shows the vehicle at the “Mojave” site, where its drill collected the mission’s second taste of Mount Sharp. The scene combines dozens of images taken during January 2015 by the Mars Hand Lens Imager (MAHLI) camera at the end of the rover’s robotic arm. The pale “Pahrump Hills” outcrop surrounds the rover, and the upper portion of Mount Sharp is visible on the horizon. Darker ground at upper right and lower left holds ripples of wind-blown sand and dust. Full image and caption via NASA web. Credit: NASA/JPL-Caltech/MSSS
The transmission is part of a routine quarterly test of the communications link between MEX and Curiosity – NASA’s Mars Science Laboratory (MSL). Aside from its prime science mission, Mars Express is able to provide contingency communications with MSL (or with any NASA rovers) in case of any problems with the normal data relay links.
This particular test consists of MEX hailing MSL – sending a specific signal requesting MSL to listen – then transmitting commands (provided by the MSL team at NASA/JPL) to the rover and then recording data transmitted back.
Background sequence of activities
MEX mission planning system schedules pointing of MEX’s UHF (ultra high-frequency) antenna at MSL – end-December 2104
MSL team provides command file (i.e. the telecommands to be transmitted) to the MEX flight control team at ESOC – last week of February 2015
MEX flight control team uploads the commanding ‘products’ (files to be executed on board MEX) on 27 February; these were generated on 24 February
Mars Express orbiting the Red Planet – artist’s impression Credit: ESA/Alex Lutkus
Operations timeline today
All times UTC
14:29 MEX will slew from Earth pointing to pointing its UHF antenna at MSL on the surface
14:41 MEX UHF antenna switches on – takes 15 mins to warm up
14:56 Overflight begins with MEX hailing MSL; overflight lasts 9 mins
15:05 MEX begins to slew back toward Earth pointing
Data received from MSL will be transmitted back to Earth by MEX at around 16:30 UTC via ESA’s deep-space ESTRACK station in Malargüe, Argentina.
Later, NASA’s deep-space network teams will extract the data from the MEX packet archive and pass this on the the MSL team for analysis.