Greek as­tro­physi­cist ex­plains Mes­sen­ger mis­sion to Mer­cury

Kathimerini English - - Life - BY YIAN­NIS ELAFROS

Stama­tis Krim­izis con­tin­ues to ex­plore the uni­verse with the ex­cite­ment of a child gaz­ing at the stars, even though he has al­ready en­joyed a lengthy and dis­tin­guished ca­reer.

The lat­est achieve­ment by the Chios­born as­tro­physi­cist and his as­so­ciates is NASA’s Mes­sen­ger mis­sion to Mer­cury, which has just cel­e­brated two months in or­bit around the planet near­est to the sun.

The 55-mil­lion-kilo­me­ter jour­ney from Earth to Mer­cury took the Mes­sen­ger space­craft about six-and-ahalf years, but achiev­ing this jour­ney re­quired some pi­o­neer­ing tech­nol­ogy, ac­cord­ing to Krim­izis.

“Mer­cury is very close to the sun. Its sur­face tem­per­a­ture is 426 de­grees Cel­sius, while the mag­ni­tude of the so­lar ra­di­a­tion is 11 times higher than it is on Earth,” the sci­en­tist, who was in Athens to de­liver a lec­ture, told Kathimerini. “We de­signed a spe­cial sun shade, un­der which the space­craft can be safe at a tem­per­a­ture of 30 de­grees Cel­sius.”

The de­sign of the Mes­sen­ger space probe and of the mis­sion, as well as its over­all su­per­vi­sion, is a pro­ject be­ing run by the Johns Hop­kins Univer­sity Ap­plied Physics Lab­o­ra­tory, of which Pro­fes­sor Krim­izis is the di­rec­tor. The tem­per­a­ture was not the only chal­lenge the team faced, as the space­craft also had to be very light and still be able to carry the fuel needed to make its jour­ney. To this end, the team built a ti­ta­nium gas tank and when the 1,100-kilo­gram Mes­sen­ger took off, 600 kg of that weight was fuel.

So far, Mes­sen­ger has suc­cess­fully or­bited Mer­cury 100 times. It can de­scend to a dis­tance of 500 kilo­me­ters from the planet’s sur­face, but it can­not stay there for too long due to the risk of over­heat­ing.

“We ac­ti­vate the in­stru­ments when Mes­sen­ger is near the sur­face,” ex­plained Krim­izis. “It takes a lot of skill to nav­i­gate it, be­cause if it be­comes ex­posed to the so­lar ra­di­a­tion it will last just 20 min­utes.”

What has the ex­ploratory space­craft dis­cov­ered so far? “First of all,” said Krim­izis, “we dis­cov­ered the big­gest basin [or crater] in our so­lar sys­tem, with a di­am­e­ter of 1,550 kilo­me­ters. We have also recorded signs of older vol­canic ac­tiv­ity, such as so­lid­i­fied lava. Mer­cury has a low­pres­sure at­mos­phere, which means it is sub­ject to harsh so­lar wind, as well as a strong mag­netic field, though this is some­thing we al­ready knew.”

In spite of this great achieve­ment, Krim­izis isn’t will­ing to rest on his lau­rels. “Our next pro­ject con­cerns an ap­proach to the sun and its study from as close as pos­si­ble,” he re­vealed. “This is a mas­sive tech­no­log­i­cal chal­lenge as the tem­per­a­tures are huge. But as I’ve al­ready ex­plored eight plan­ets in our so­lar sys­tem, I have now set my sights on the sun.”

What drew this boy from Vronta­dos on the is­land of Chios to pur­sue stud­ies in as­tro­physics at the uni­ver­si­ties of Min­nesota and Iowa in the USA and to be­come part of the avant-garde of space ex­plo­ration? “Ex­plor­ing the un­known, pro­duc­ing new knowl­edge and an­swer­ing some of the most fun­da­men­tal ques­tions, like how the so­lar sys­tem was formed, where we came from and where we are go­ing,” he said.

Krim­izis is also a mem­ber of the Athens Academy, the Greek Na­tional Coun­cil of Re­search and Tech­nol­ogy, and pres­i­dent of the In­ter­na­tional Academy of Astro­nau­tics.

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